Category: Analysis

Anything that I have tested empirically, or explain with detailed calculations, or just generally bother to get all the facts straight.

Post #1703: Four simple rules for protecting the lithium-ion battery in a Prius Prime

 

Background

Source:  Geotab.

So far, on average, the lithium-ion batteries in the Prius Prime appear to be holding up well.  The small sample of 2017 Prius Primes used for the graph above lost range at a rate of just four percent over the first three years of operation.  That’s just a touch better than the average EV.

Within that overall good average, some individuals are going to get outstanding battery life, and other’s won’t. 

That’s not a matter of luck.  For example, the Geotab site (source of the graph above) summarizes the predictable loss of battery life due to high heat, fast charging, and so on.

As Toyota itself says (emphasis mine):

 

Source: 2021 Prius Prime warranty booklet.

As far as I can tell, the use of “drastically” above is correct.  Based on the National Renewable Energy Laboratories analyses presented in the prior post, treating the battery gently could result in two-to-three fold increase in battery life, compared to abusing it.

Here’s a bit of data from Tesla to illustrate.  The X-axis is how much the battery has been used, in total KWH.  The Y-axis is the remaining range.  (Note:  Full range of the vertical axis as shown is about a 20% capacity loss of the battery.)  There is, in fact, quite a spread around the average capacity loss.   Of the two data points highlighted, for roughly the same battery use, one has lost about 5% of capacity, the other has lost nearly 20%.

Source:  Electrek.co.  Annotations in red are mine.

 

The rules.

The rules for long battery life given below are based on the evidence and analysis in the just-prior post.  But, in fact, these are all well-known rules for extending lithium-ion battery life.  If you look around, you’ll see that more-or-less everyone says more-or-less the same thing.

Rule 1:  Avoid charging to 100%.

  • Don’t charge to 100% unless you absolutely need that full range.
  • More importantly, don’t charge to 100% and let the car sit unused.
    • If you’re going to charge to 100%, use the charge scheduling software so that the car reaches 100% just before you drive it.
  • Even more importantly, don’t charge it to 100% and let it cook in the sun.
  • The most common suggestion is to charge to 80%.  Not clear if that specific number is anything more than a rule-of-thumb.

Rule 2:  Avoid temperature extremes, particularly high heat.

Rule 3:  Avoid high-current events in EV mode.

  • Avoid rapid acceleration.
  • Avoid fast stops.
  • Arguably, avoid driving at highway speeds in EV mode.
    • The faster you go, the gentler your driving should be.
  • Minimize high-current events by driving in EV AUTO mode — punch the right-most button on your driving mode selector.

Rule 4:  Use shallow charge-discharge cycles whenever possible.

  • Get out of the habit of charging to 100% and discharging to 0%.
  • Get into the habit of charging/discharging over a narrower range, e.g., charge to 75%, recharge when it hits 25%.

There are a handful of rules that aren’t cited here because they don’t apply to the Prius Prime.  Frequent use of a fast charger reduces battery life.  But you can’t do that in a Prime anyway.  Discharging the battery down to zero is bad, but, again, you can’t do that in a Prime.  The Prime reserves the last portion of capacity for use as the hybrid battery.

In a sense, this is just a natural extension of what prudent drivers have done all along to avoid unnecessary repair costs.  In a conventional car, if you want your brake pads to last, you aim for nice, gentle stops.  And now, if you want your battery electrodes to last, you do the same thing.  Plus some.

Discussion, Part 1:  An unusual automotive situation.

For the last two posts (#1702, #1701), I’ve been getting my mind around the fact that there’s no warranty on the EV range of a Prius Prime.  The more deeply I dug into this, the more appalled I got.  Briefly:

  1. Most people buy this car, instead of a standard Prius, specifically because the car can be driven as an EV for a considerable distance (25 miles, per EPA).
  2. But Toyota provides no warranty on that key EV capability.  If your EV range drops to zero, but the car still runs as a gas hybrid, tough luck.  (You have to read the “exclusions” section of the warranty document (above) to know that.)
  3. Worse, the owner’s behavior can greatly affect the lifespan of the battery.
  4. Worse still, many of the unchangeable defaults on the Prius Prime are not optimized for best battery life.
  5. The simplest way to use the car — plug it in when  you get home, drive it the next day — is really bad for battery life.
  6. Toyota’s directions on best practices consists of a brief section buried in the middle of the 800-page owner’s manual.

Source:  2021 Prius Prime owner’s manual

In short, the lithium-ion battery in a Prius Prime is an expensive, effectively un-warrantied car part that you, the owner, can easily screw up over time.   The obvious default consumer behavior — plug it in when you get home, and let it charge — is absolutely the wrong thing to do.  Many of Toyota’s default settings do not optimize the life of the battery, and you have to work around those manually if you want to get best battery life.

This is so out-of-touch with modern automotive engineering that I’ve had a hard time getting my mind around it.  If you want to get the most out of that battery, then you, the owner, have to go out of your way to do that.

Think about it.  When the car needs an oil change, it tells you.  If you run low on oil, it’ll shut itself off to avoid damage.  But if your behavior is quietly cutting years off the life of your lithium-ion battery?  Nada.  It’s entirely on you to figure that out and adjust accordingly.

Discussion Part 2:  YOLO, or once you’ve lost EV range, there’s probably no going back.

Premature battery wear just gets worse when you put it in the context of what should be an extremely-long-lived vehicle.  I’m guessing that as long as the car runs as a gas hybrid, few people will be willing to pay to replace that battery merely to restore full EV function.  Best guess, once that EV capacity is destroyed, it’s gone for good.

First, all other things equal, I would expect these cars to have an extremely long service life.  That’s a consequence of the robustness of electric motors, and the fact that you have both EV and internal-combustion-engine (ICE) power on board.  For example, my wife’s car has about 11K miles on it in a year-and-a-half of use.  But I’m guessing the gas engine has no more than 3K miles on it.  At that rate, that car will hit 150K on the gas engine literally next century. 

I don’t expect it to last that long.  But if our 18-year-old Prius is still running well with 230K on it, I see no reason this car — and many others like it — couldn’t make it to 500K miles.

Extreme car lifetimes are the trend, not the exception.  When I was a kid, odometers only had five digits, because it was almost-unheard-of for a car to make it to 100,000 miles.  You more-or-less expected to need an engine rebuild (“valves and rings”) over that period.  Today, a car that failed with only 100K on the odometer would be considered a lemon.  (Well, surely a Toyota that failed at that point would be.)  So why shouldn’t the next generation of cars kick that up a notch?  Tesla, for example, predicts 300K to 500K service life before the batteries need to be replaced.  I don’t see why Toyota can’t match Tesla in that regard.

My point is, Toyota might consider 150K miles to be “the life of the car”, but I sure don’t.  And I expect that for this particular model, a whole lot of them are going to last much longer than that.  So the question isn’t “will this battery last 10 years”, the minimal question that needs to be asked is, “how’s this going to drive 20 years from now”.

Here’s the final reason you want to take really good care of that battery:  Replacing the battery to restore EV range will not be cost-effective.  If you lose most of your EV range, but the car still runs fine as a gas hybrid, replacing that battery, solely to restore EV range, will almost certainly not pay for itself in fuel savings, for most users.  So, if not for your own use, then for the string of people who will own the car after you, you really want to make the battery last as as possible.

Above, you see how the calculation looks for me, under the assumption that the battery lasts 3000 full charge/discharge cycles.  (Tesla, which uses more-or-less the same cells, originally claimed that their batteries could do 1500 cycles before losing 30% of range.  Real-world data from Tesla suggest slightly better performance: just 10% capacity loss at 200,000 miles (reference), which projects out to about 22% average loss of range over 1500 full charge/discharge cycles.)  This calculation uses my current gas and electricity costs, and grid footprint, and assumes a new battery could be installed for $5K, which is the best rumor I’ve read so far about that cost.

The gas savings from restoring full EV range wouldn’t come close to the (assumed) $5K cost of battery replacement.  Based on that, I’m guessing that as long as the car still runs well as a gas hybrid, lost of most or all EV range will not motivate most owners to re-battery the car.

Edit 2/11/2023:  I grossly underestimate the replacement cost for a Prius Prime lithium-ion battery.  Per this thread on Priuschat, the cost of new Prius Prime battery, from the dealer, is $12,595.  Others suggested the dealer took some markup, as the list price from Toyota is just under $10,000.  I say, potato, potahto.

In round numbers, the cost of a new replacement battery is 43% of the cost of a brand-new Prius Prime, base model, current MSRP $28,770.  As a footnote, literally none were available in North America, and the battery has to be shipped directly from Japan.

I should put in the usual EV-weasel-wording:  By the time the battery dies, there will be plenty of good-used batteries in junkyards, from wrecks.  That did, in fact, happen with the original Prius NiMH hybrid battery.  Plus, there may be much cheaper aftermarket replacements at some point.  And so on.  But right here, right now, what I cited are the hard numbers for battery replacement cost.

Original post follows.

My conclusion is that as far as the Prius Prime battery is concerned, it’s a straight-up case of YOLO.  I expect these cars to last a long time.  And I expect that almost all of them are only ever going to have that original factory battery, no matter how long they last.

So, if you bought this car for the EV capability, the moral of the story is, do what you can to take care of the battery.

Discussion Part 3:  Manual timers, radiant barrier cargo area mat, and other workarounds for unhelpful Toyota defaults.

This last is just a list of things I’ve come across that I wish I could change.  Perhaps some future software update/production change will address some of these issues.

No way to charge to less than 100%.  This is probably the most critical problem.  The default is to charge until the battery is full (100%).  Near as I can tell, there’s no way to change that. 

Other vehicles, such as Tesla, allow the user to charge to less than 100%.  That’s good for battery life.

As it stands, the only way to keep the charge below 100% in a Prime is to interrupt the charge circuit yourself.  I’ve bought a “countdown” timer for this purpose (see prior post).  Based on the car’s state of charge, and with a target of no more than 80% charge, I’ll set the timer manually to stop the charge at roughly the right point.

It doesn’t get more Mickey-Mouse than that.  But Toyota does not provide any way to stop the charge before 100%.

No way to set EV AUTO as default on startup.  The default is hard-coded as EV.  That is, you lock the car into using the battery no matter what.  If you want EV AUTO — so that the car will automatically switch on the gas engine if it’s stressed, rather than withdraw high current from the battery — you have to remember to punch that button every time you start the car.

So I now have a sticky note, on the steering wheel, that says “EV AUTO”, to remind me.  More Mickey-Mousery, but Toyota does not allow you to change the default mode at startup.  Or if they do, I sure haven’t seen it.

No warning for excessive current draw/no native monitor for battery current.  I understand that Toyota set the car up with limits on peak battery current.  Those have to be set to allow adequate emergency acceleration.  The almost certainly are NOT set up to provide peak battery life.

I’d like to have something that lets me know when the car is drawing a high current out of the battery.  Not prevent it, just let me know when that’s happening.

In the past, I’ve had cars that had an “eco” light on the dash.  Push down on the gas too hard, and the light would come on to remind you to back off for better gas mileage.  Or to shift, back in the days of manual transmissions.  That’s all I’d want, really.  Just a little reminder not to drive in such a way as to shorten battery life unnecessarily.

As with the first two, I’m going to have to roll my own if I want that capability.  I assume the current generation of ScanGauge or similar will let me see instantaneous battery current.  So, in effect, I’m going to have to add an aftermarket gauge to the car, because Toyota does not provide that as a native capability.

Edit 1/27/2024:  I bought and plugged in a ScanGauge III, and it works perfectly for this purpose.  (It also lets you check battery temperature, battery fan operation, and other more routine stuff, such as tire pressure.) 

My main observations are that a) for high-current events, the brake pedal is more dangerous than the accelerator (even a moderately hard stop can generate 125 amps of regen current), and b) the “eco” bar on the Prius display is set to encourage you to draw no more than about 50 amps of current on acceleration.  That 50-amp draw works out to a “2C” rate of discharge (the amount which, if you kept it up, would drain the battery in half an hour), a reasonable rule-of-thumb for limiting current draw of a lithium-ion battery.  That also works out to about (350V x 50A = ) 17.5 KW of power, or about 23 horsepower.  Which, in turns, works out to a rate of acceleration that pisses off Northern Virginia drivers, so I routinely push the car over that limit when I’m in traffic.  If left to my own devices, I do what the car tells me to do.

Bottom line is that the eco-meter on the dashboard tells you all you need to know about acceleration.  Obey it if you can.  For braking, though, it’s not helpful.  (Which, when you think about it, is no surprise.)  Absent a ScanGauge or similar, you just have to realize that a heavy foot, at high speed, generates a lot of power.  Per Newton’s laws (Post #1618), to stop the car in a given distance, with minimum peak current, you start with a light foot and press harder as the car slows.   

No radiant barrier, parked-car ventilation system or other summer heat protection.  Toyota specifically warns you not to charge the battery up, then let the car sit in the hot sun.  Which is great, but it would be even better if there were some entirely-passive or partially-passive methods built into the car to limit interior summertime temperatures when parked.

BMW, for example, offers a “parked car ventilation system”, which is exactly what it sounds like (reference).  You can ask the car to run the fan and blow fresh air through the car while it is parked, to keep the temperature down.  Tesla offers a similar function as “cabin overheat protection (reference).  (In addition to a “Dog” setting, which will run the AC when parked.)

You know what’s even more irritating?  Toyota has one too, but it was only offered on the Prius when you got solar panels on the roof.  Toyota literally knows how to do this, already, they just didn’t bother to offer it for the Prius Prime.  Given that summer heat is quite destructive to a lithium-ion battery, you’d think that Toyota could have modified a bit of computer programming to add this already-existing feature to the Prius Prime.

And even more irritating than that?  The Prime is perfectly capable of running the AC for a few minutes before you get into the car.  You can trigger that with the fob, or with the Toyota phone app.  But there’s no way to automate that to (say) keep the interior temperature below 100F.

For my part, I’m at least going to add a sheet of radiant barrier in the cargo area.  Basically, a space blanket, but tougher.  Without getting into the physics of it, as long as there is an air gap on one side or the other, radiant barrier prevents passage of infrared equally well whether the shiny side faces up (into the sunlight) or down (into the cargo compartment).  (Weird but true, which is why I’m not going to get into the physics of it.)  So if the cargo compartment is empty, it would work just about equally well if laminated to the underside of the tonneau cover cloth, or just sitting on the floor of the cargo compartment.

Given the critical role that heat plays in damaging lithium-ion batteries, you’d think that this cheap-and-simple aid would be standard on Prius Primes.  Something as simple as reflective mat for the cargo area.

Edit 1/27/2024:  In the end, a “reflective floor mat” is exactly what I ended up with.  I took a piece of construction radiant barrier and covered the floor mat in the cargo area.  That will work as as radiant barrier as long as that’s open to the air above it, whether or not the tonneau cover is open or closed.  The surface is dull enough that I don’t have problems with reflections showing up on the back glass then the cover is open.

I might go so far as to add one of those stick-in-the-window power vents.  Those always struck me as gimmicks.  But given that heat is bad for the battery, I guess $20 invested in testing one of those may be money well-spent.

Summary

I don’t want to hype the issue of preserving battery life.  The car does a pretty good job of protecting that battery from abuse.  And, at this point, there’s little doubt that most Prius Prime owners are likely to get a satisfactory amount range, over a satisfactory lifetime, for that battery.

But some of what it takes to preserve battery life is up to you.  If you simply plug your car in when you get home, then drive it away fully charged in the morning, you are definitely not doing right by your battery.  Modifying your habits, based on a few simple rules, will go a long way toward preserving the range of your battery as the car ages.

Post #1702: There is no warranty on Prius Prime EV range. So treat your battery nicely.

 

In a  nutshell:  Toyota offers no warranty whatsoever on the EV range of a Prius Prime.  After doing a bit of calculation, I’ve come to the conclusion that’s probably because they couldn’t.  Odds are, for some of these Prius Primes, the EV range will be greatly reduced long before the car is ready for the scrap yard.

Now that I’ve reviewed the basics, I think you could plausibly see two- or three-fold difference in battery life, across users, depending on their habits and climate. 

I go over five key habits in the final section.

To summarize:

Want to kill your battery?  Routinely charge it to 100% and discharge it all the way down to 0%.  Leave it 100% charged for long periods of time, ideally, while letting the car roast in sun.  Accelerate with a wide-open throttle and stomp on the brakes to stop.  And do a lot of high-speed highway driving in EV mode.

Want your battery to live a long and fulfilling life?  Stop your charge well below 100%.  Only discharge the battery part-way before you recharge it.  Keep the car and battery cool. Drive gently, and use the gas engine when you’re on the highway.

In terms of the core question — how long should I expect my wife’s Prius Prime battery to last — I still don’t know.  If I do a crude extrapolation based on a Tesla battery (with same cell chemistry and manufacturer as the Prius Prime battery), I come up with a shockingly short lifespan.   Something like an expected 40% loss of range after 30,000 electrical miles.  And yet, my wife’s car seems to show no appreciable loss of range after about 8000 electrical miles.  So something about the crude comparison isn’t right.  I just have no idea what it is.

Edit 9/29/2024:  The salad days of 35-mile EV range (under the right conditions), in my wife’s 2021 Prius Prime, are now firmly in the rear-view-mirror.  Range took a nosedive last winter, and seems to have stayed down ever since.  The last time I drove that car, I estimated a full-to-empty-battery EV range between 20 and 25 miles.   (We got high-30s on average when new.  The EPA-rated range of the battery when new is 25 miles, but the EPA drive cycle is far more stringent than the around-the-‘burbs driving that accounts for the majority of this car’s use.)

As to why this happened, I have no good answer.  My fear is that this is just normal wear-and-tear.  Range dropped at one point, and now appears to be stable at, say, 2/3rds of what it was when new.  As the EV-usable portion of the battery is only about 60% of battery capacity (accounting for buffers for 100% charge, 0% charge, and hybrid use), a one-third decline in 60% of the battery capacity is algebraically equivalent to about a 20% decline in total battery capacity.  The car has 19K miles on it, I’d estimate 75% electrical miles (which is also what I get when I take total miles and net out an estimate of gas-powered miles on an average of three tanks of gas per year), which means that loss occurred in about 15,000 electrically-driven miles.

Which, unfortunately, puts it spot-on with my Tesla-based estimate from two years ago, just above.  (For details, see “The crude comparison falls flat on its face”, below.   Originally, I dismissed the estimate I got by extrapolating from known expected battery life for a Tesla as being implausibly short.  Now, I’m not so sure I was that far off.  So, FWIW, and crudely done, an estimated 20% loss total battery capacity, at around 15,000 miles is, in fact, halfway to the projected 40% loss at 30,000 electrical miles, which I arrived at by starting from the stated lifetime (2000 full charge cycles) for Tesla batteries, where those Tesla batteries appear to have the same battery chemistry and manufacturer as the Prius Prime battery. 

The good news is that the range dropped, all at once, but has stabilized since.  Maybe something catastrophic happened last winter, producing a one-time large decline in range, but no error codes or warning lights.  But my bet is that the car was simply programmed to show as little loss as possible early on, as a consumer-satisfaction measure.   Best guess, that sudden one-time drop in range doesn’t mean that range will sink like a stone from now on.  I’m betting that it just means that the software clicked past some threshold, and all the previously-hidden range decline is now visible to the driver.

But arguing against that, nothing I could see about the state of battery charge, using a ScanGauge 3, suggested anything of the sort.  So this mythical “software threshold” may be a figment of my imagination as I try to explain away the sudden, seemingly one-point-in-time, steep range loss.

Bottom line is that we lost a chunk of range, all at once, and I have no good idea why that happened.

Edit 10/19/2023:  After more than two years now, my wife’s Prius Prime still shows no noticeable loss of EV capacity.  We consistently get 36 to 40 miles of EV range (AC/heat off).  (That’s much better than the EPA rating of 25 miles of EV range, but all of our EV driving is suburban-low-speed driving.) 

My point is, don’t take this post as a slam on Toyota.  Car companies typically offer no range warranty for their PHEVs (Volvo being the only clear exception I’ve come across so far.)  See Post #1707 for the long list of car companies that don’t offer a range warranty on their PHEVs.

The well-known reality of lithium-ion batteries is this: You can kill them if you abuse them.  And hey, guess what, that applies to all lithium-ion batteries, including the ones in your car.  Your car’s battery management system will do its best to stop you from killing your batteries.  But it can’t do everything. 

It’s up to the driver to avoid doing things that shorten battery life.  For real.  No kidding.  As-reflected in the (lack of) range warranty.  That’s the only point of this post. 

Why Toyota couldn’t provide a four-page leaflet on the care and feeding of your lithium-ion battery, I have no clue.  Because I knew none of this stuff, above, before this latest deep dive. In fact, many of the default settings on the car are not optimized for good battery life and can’t be changed.  Likely, the Toyota battery management system guards against the worst of your habits.  Still, if you want the battery to last as long as possible, you need to get into the habits that will do that.

Continue reading Post #1702: There is no warranty on Prius Prime EV range. So treat your battery nicely.

Post #1701: Prius Prime warranty documents. I laughed. I cried.

This post started off as a little analysis of electric vehicle battery life, but soon went off the rails.

As it stands, it’s probably useful only if you are considering buying a plug-in hybrid electric vehicle (PHEV).  Particularly a Toyota plug-in vehicle.  If you are, it may be well worth reading.

To be clear, my wife’s 2021 Prius Prime is running fine.  No problems.  Then again, it’s less than two years old.

The upshot is that I have more-or-less no warranty on the PHEV battery in my Prius Prime.  Which is not at all how it looks, if you read the description of the warranty on Toyota’s website.  Nor how it looks, if you look at Federal legal warranty requirements on EV batteries.

Ultimately, this is a story about about a loophole in a well-intentioned Federal regulation.  And what you can learn when you bite the bullet and actually read your car’s owner’s manual.  Including the footnotes.

Critically, it means you shouldn’t drive one of these cars to use the least gasoline you can, right now.  No matter how enjoyable the resulting bragging rights might be.  You should drive them to preserve the life of the battery for as long as possible.  And those are two quite different driving strategies.

Background

The Federal government requires that all electric vehicles (EVs) sold in the U.S. include at least an 8-year, 100,000-mile warranty on the EV battery.  That’s a floor, not a limit.

California require 10 years/150,000 miles.

And, of course, some manufacturers may offer more than that.  Although most offer the US mandated 8/100,000, Toyota chose to offer the California-level warranty for all cars sold in the U.S.  So, my wife’s Prius Prime battery is covered by a 10-year, 150,000 mile warranty.

I just looked that up in the warranty documents that came with the owner’s manual.

I laughed.  Lucky me.  Go Toyota!  That battery must be bulletproof.  I’m gonna drive the heck out of it, to be sure I get my money’s worth.

But this is PHEV.  How can they do that?

Then I started thinking about that, and something didn’t quite add up.

The key thing you should realize is that using a battery for PHEV just beats the crap out of it, compared to using it in an electric vehicle.  Allow me to explain.

By and large, the main determinant of lithium ion battery pack life is the amount of electricity you run through it.  The industry standard is based on the number of full charge/discharge cycles the battery pack can take before it loses 20 percent of its capacity.  (If you only do a fraction of a full charge or discharge, you count that fraction toward the total).

(Separately, there’s “calendar aging” in addition to charge/discharge cycles, but that’s for another day.)

Because a PHEV battery is small, a given amount of driving will run you through a lot more charge/discharge cycles than you would in a full EV.  For example, a 30-mile daily work commute would put about five cycles per week on the Prius Prime battery, but only half a cycle per week on one of the upper-end 300+ range Teslas.

If you were to put batteries with the same chemistry and construction in a Prime and a Tesla, and drove those cars the same way (which would never actually happen, as any Tesla driver will attest), all other things equal, the battery in the Prime will fail way, way before the battery in the Tesla.

Let me put some real-world numbers on that.  At this point, Tesla’s battery chemistry may be a bit older than the current best.  But not by much.  Those Tesla battery packs are supposed to go 1500 full charge/discharge cycles before failure.

At 1500 full cycles, then:

  • A Tesla with a 300-mile range would travel (1500 x 300 = ) 450,000 miles to battery failure.  This is why you’ll hear Tesla owners say their batteries are good for half-a-million miles.
  • A Prime, with a 30-mile range, would travel (1500 x 30 = ) 45,000 miles to battery failure.  (Assuming all travel was done on electricity.)

Even assuming something more normal — that only half the Prime miles are traveled on the battery — the Prime, with a Tesla-like battery chemistry, would still be seeing frequent battery failures around 90,000 miles.

How can Toyota warrant those batteries for 150,000 miles?

Is the Toyota battery that much better than the Tesla battery?  (After all, it was developed a lot more recently, and batteries have been improving.)  But still, even as much as I am something of a Toyota fanboy, for the longevity of their vehicles on average, something about this didn’t quite add up.

Warranty?  Not really.

Now we get to the part where I cried, from reading the owner’s manual.

To get to the punchline, the joker in all of this — the Federal regulation, and the Toyota warranty — is what you mean by “battery failure”.  Sure, the Feds require that you warranty the battery against failure for 8 years or 100,000 miles.  But the manufacturer gets to define what “battery failure” means.

You can easily find examples on-line.  Tesla adopts a 70% threshold for battery failure.  If you lose more than 30% of your range, in your first eight years of ownership, they’ll replace the battery.  Nissan uses a 75% threshold for the Leaf, but seems to measure it in a somewhat non-standard way.  VW uses a 75% threshold.

Those are all EVs.  Where the only way to make the car go is electricity.

But the Prius Prime is a PHEV.  Electricity is not the only way to make the car run.  It can run as either an EV, or as a standard gas hybrid.

For the PHEV function of the Prius, Toyota effectively adopts a threshold of 0%, for battery failure.  As long as the battery is good enough to run the car in hybrid (gas) mode, then according to Toyota, it hasn’t failed.  Which means that if my PHEV range drops to zero, well, tough.  As long as it’ll still run as a standard Prius, the fact that it has no PHEV range does not qualify the battery as having failed.

Or, as Toyota puts it, loss of range over time is normal, and is not covered by the warranty.

The upshot is that I have literally no warranty on the PHEV function of the Prius Prime.  A fact that — trust me on this — you would never figure out by looking at Toyota’s website.  Or, near as I can tell, anywhere else.

Based on the literal Toyota warranty documents, mere loss of capacity is not failure.  Up to and including all PHEV capacity.  If my electric range dropped to zero tomorrow, but there was still enough battery left to run it as a gas hybrid,  I’d have to eat the cost of a fix, to restore PHEV capacity.

Moral of the story:  Read The Fine Manual (RTFM).

A change of decoration is in order

Now that I know the full scoop — that far from offering a 150,000 mile on the PHEV function of the battery, Toyota offers zero — I need to change a few things about the way I drive that car.

Or, putting it bluntly, I’ve been pretty stupid about how I drove the Prius Prime.  I’ve been using that battery like there’s no tomorrow.  Because, hey, with a 150,000 mile guarantee, I assumed there was no tomorrow.   I assumed Toyota built that well enough that I’d see no serious degradation of PHEV range for the first 150,000 miles or so.  And I now realize that was all just my misunderstanding of the fine print of the warranty.

I’ve been living in a fool’s paradise by trying to burn as little gasoline as possible.  Look at me, see how environmentally conscious I am.  All the while, fully understanding that EVs trade off battery wear and tear for gasoline consumption.  I just stupidly believed the 150,000 mile warranty assumed me that the tradeoff in the Prime was minimal.  When the reality is that if I drive all-battery now, chances are I’m going to end up driving all-gas later.

And that changes now.  From this day forward, I drive for minimal battery wear-and-tear.  Ultimately, the longer the battery lasts, the more gasoline I will save in the long run.

First, I’m going to stop doing highway driving in EV mode.  One of the nicest surprises of the Prius Prime is that the EV side of it was more than adequate to do highway driving.  So my habit was simply to run down the battery, no matter what the trip was.  And if that meant getting on the interstate in EV mode, no problem.  But I see in forums for other PHEVs that highway driving in EV mode is discouraged, owing to high battery drain.  So from now on, if we’re on the highway, we’ll be burning gasoline.

Second, I’m going to punch the EV Auto button every time I get in the car.  Arguably the least-well explained controls on the Prius Prime are the three buttons that determine mode-of-propulsion.  (This next bit will only make sense to Prime owners).

  • The one on the left is for pedal feel.  Ignore it for this post.
  • The one in the middle lets you choose to lock the car into EV mode, or into standard Prius Hybrid mode.  (Labeled as EV/HV mode.)
  • The one on the far right lets the car choose which mode is best.  (Confusingly labeled as EV Auto mode).

Again, I should have known better.  With all things Prius the right answer is always “let the car decide what to do”.  In “EV Auto” mode, the car will kick on the gas engine under higher loads, and so forth, as it sees fit.  Avoiding high loads on the battery should be good for longevity.

For whatever reason, Toyota makes EV Mode the unchangeable default at startup.  (Plausibly, because they knew their customers were a bunch of eco-nerds like me.)  So from now on, punching the EV Auto button after hitting start is going to be SOP.

Third, I’ve bought a countdown timer to prevent the battery from charging to 100%.  The owner’s manual offers some mostly-lame advice on extending battery life.  But one useful thing it suggests is to use the charge scheduling function so that the car is fully charged just before you use it.  The inference (actually a well-known phenomenon) is that leaving a lithium-ion battery in a high state-of-charge puts wear-and-tear on it.  We have no fixed schedule, so I’m going to do the next best thing.  Based on state-of-charge when we park the car, I’m going to dial in all but the last hour of required charging.  At that point, I’ll either typically use the car starting from 80% charged, or be smart enough to plug in an hour before I intend to use it.

Conclusion, and loophole, defined.

Anyway, it all boils down to a loophole.

If you buy a hybrid, with a battery warranty, you know what that means. It’s black-and-white.  It means the battery has to be in good enough shape to run that hybrid.  On a Prius, when the hybrid battery fails, the car is un-driveable.  Hence, a 100,000 mile warranty on the hybrid battery was easily understood.

If you buy an EV, with a battery warranty, you know that that means, even it it isn’t as crystal-clear as for a hybrid.  It means that the manufacturer will replace the battery if your loss-of-range exceeds a clearly stated amount.

But if you buy a combination EV-hybrid — a PHEV — your warranty gets lost in the cracks.  You buy it for the EV, but you only get a hybrid’s worth of warranty on the battery.  If the battery fails so badly that the car won’t run as a hybrid, they’ll replace it.  Otherwise, tough luck.

And not only did I not realize that, not only was that hugely unclear from Toyota’s promotional materials, but I’ve been driving the car as if that 150,000 mile warranty meant that Toyota expected that much usable PHEV life out of the car.  When, in fact, that’s just not true.

Not that I think Toyota would have made an inferior product.  But when Toyota said that they expect the battery to last the life of the car, I mistakenly thought that meant the PHEV functionality would last the life of the car.  Which I now seriously doubt.

So I’ve gone from a false sense of certainty, as to how this car will perform in the future, to a high degree of uncertainty about it.  Doesn’t mean its going to run like a three-legged dog at 100K miles.  But it might.  Which would be very un-Toyota-like, in my experience.

I should have known better.  It was the worst sort of magical thinking.

I was living in an eco-Fool’s paradise.  And that changes today.

Post #1698: Razor-blade longevity test, the redo

 

This post replaces all my prior posts on extending the life of a razor blade.  Because, I think I goofed.

Based on my most recent analysis:

Whatever it is that dulls a razor blade, short of abuse that puts big nicks in the blade, you can’t see it under a low-magnification microscope.  Blades that appear perfectly sharp, and (by measurement) retain their full width, can, nevertheless, be too dull to remove your beard.  I have no idea why.

The ONLY test for whether a razor blade remains sharp and usable is to shave with it.  Neither examining it with a low-power (USB) microscope, nor testing it with a home-made sharpness tester, provided useful information on how well a blade would shave.

Of the three things commonly cited on the internet, for extending the life of a razor blade, I now believe that:

  1. Softening your beard prior to shaving is critical for razor blade life.
  2. Drying off your razor blade — even a stainless steel blade — is necessary to keep it from dulling prematurely.
  3. Once it goes dull, there’s nothing you can do.  Stropping a dull stainless steel blade does not return it to a usable state.

Number 2 is a change from my prior posts, and that’s really the key point of this post.

Edit:  And I now know why:  Water spots.  A calcium carbonate deposit (a.k.a., water spot) is much thicker than the edge of a razor.  Tested and confirmed by comparing distilled water to tap water, Post #1699.

The upshot is, if you use shaving cream or (arguably) a high-end shaving soap, and dry your blade after each use, you’ve done your due diligence to get the most out of your razor blade or disposable shaver.  Whether more extreme measures add to that — keeping the blade stored in oil, freezing it, or whatnot — would require more analysis.

A recap and a bit of detail follows.

Recap

I’m trying to determine whether any of the suggestions for extending blade life, commonly found on the internet, actually work.

I boiled this down to:

  • Dry your blade
  • Strop your blade
  • Soften your beard.

I wanted to be as objective as possible, so I tried to avoid rating blades based on how the shave felt, figuring, there’s a lot of subjective leeway in that.  Instead, I was going to rely on how the looked, and how sharp they appeared to be, based on a home-made sharpness tester.

In hindsight, that was a mistake.  Appearance was an adequate way to judge blades if they were thoroughly abused.  But for blades that have not been abused — without visible nicks or erosion in the edge — it turns out that a sharp, usable blade looks just like a dull, unusable one.

Results.

Soften your beard/lubricate your face:  CONFIRMED

If nothing else, this razor blade test has broken me of a life-long bad shaving habit.  I shave(d) with soap.  Most recently I’ve been using Dove, because that’s supposed to have more emollients in it and be generally nicer to your skin.

And, not unrelated, I’d typically get three shaves out of a blade before I got the urge to replace it.  Maybe five, at the outside.  But by the time I got through that fifth shave, it required multiple passes of the blade and, basically, it hurt.

For this final test, I decided to shave half my face using Dove soap, and half with Barbasol.  The main active ingredient in Barbasol is stearic acid.  That’s the same as the main fat in coconut oil, and it is frequently recommended as a beard softening agent.

From the first shave, it was absolutely clear that shaving with Barbasol was a lot better than shaving with soap.  In the end, I got ten decent shaves with Barbasol, versus a typical 3 to 5 shaves with soap. 

That one is case closed, as far as I’m concerned.  I’d conservatively say that using Barbasol easily doubles blade life, relative to shaving with Dove soap.

If you want a more in-depth dive into the ingredients of shaving cream and shaving soap, see Post #1668.

Strop your stainless steel blade:  Busted

Stropping means running the blade “backward” — opposite the direction of cutting — over some suitable material.  The idea is to polish and hone the very final edge of the razor’s edge.

The practice of stropping razor blades to re-sharpen them disappeared just about the same time that stainless steel blades (above) took over the market.  I strongly suspect that this was cause-and-effect.  Stainless razor blades are just too hard (or wear resistant, take your pick) for stropping to have much effect.  I went through this in the historical perspective on stropping, Post #1689.

I have now tried all of the following, and none of it resulted in restoring a dull blade to usable status.  I.e., from the standpoint of shaving, none of this sharpened a stainless steel blade:

  • Stropping on a leather strop, blade held in razor.
  • Stropping by rubbing on the inside of a plain water glass.
  • Stropping by rubbing on the inside of a curved borosilicate glass.
    • Low curvature (measuring cup)
    • Higher curvature (oil lamp chimney base)
    • High curvature (oil lamp chimney top)
  • Stropping on borosilicate glass, with abrasive metal cleaner
  • Stropping using a standard carbon-steel knife steel.
  • Stropping using a commercial leather strop plus green “compound”.

None of that seemed to make the least bit of difference in how well the blade shaved.  In particular, using an actual commercial leather strop and compound, 30 strops, did nothing to restore a blade to usability.

Finally, literally sharpening a blade — removing significant amounts of material from the blade edge — destroys its usability.  It makes it too narrow for the safety razor, and it then leaves stubble instead of cutting cleanly.

Stropping, steeling, sharpening, and so on.  Total bust.

Dry your razor after use.  I’ll be damned.

 

For this one, I cooked up a fairly elaborate experiment to show that nothing happened to stainless steel blades if you leave them wet.  I took six blades (three new, three used), kept one edge wet for a week (either continuously, or dunked in water once a day), and kept the other edge dry.

And, by eye, there was absolutely no difference, under a low-powered microscope, between the wet and dry edges.  There was no difference in sharpness, based on my crude sharpness tester.  So I originally concluded that drying a stainless blade after every use is unnecessary.

Then the stropping experiment finally ended, I put a different razor blade in my razor.  This was one of my test blades above, and I expected it to shave like a new blade.

Well, I was half right.  One side shave just like a new blade.  The other side was so dull as to be unusable.

When I pulled it out of the razor, the unusable side was the one that had been dipped in water a few times a day, for a week, and left to dry at room temperature.

So, I’ll be damned.  I can think of no other explanation for this, other than, failing to dry off that blade, for what amounts to a couple of week’s worth of dunking, left it dull.

I may look a little more carefully at this.  I want to repeat that.  And some people say that extreme measures can preserve blade life even further.  Others claim that the dulling is due to build-up of minerals on the blade, from hard water.  So I may want to look at all of that.

But as of right now, for reasons that I absolutely cannot fathom, it appears that you do, in fact, need to dry off a stainless blade to keep a sharp edge on it.  Or, at least, failing to do that will dull the edge.

I have no clue why that is.  I’m only attesting that, based on a sample of one blind shave with one carefully-treated blade, that appears to be true.

Anyway, dry off your stainless steel blade.  Apparently confirmed.

Edit: See next post for the explanation.  It has nothing to do with rust or oxidation of a stainless-steel blade.   Post #1699.

Post #1696: An historical note on the current Xbox kerfuffle

 

A well-known energy hog of long standing

When the recent manufactured controversy over the Microsoft Xbox hit the papers, it resonated with me.

Probably 15 years ago, we bought a gaming console for our kids.  (For the kids, of course, because we adults would never consider wasting time playing video games.)

We bought a Nintendo Wii.  Not due to the quality of the gaming, but because the Wii console used about one-fifth the energy of the Xbox and similar alternatives.  (Ask me what screen I finally got to on Wii Tanks.)  The Wii had a lot of other interesting features — not the least of which was the Mii parade above.  But the main reason I picked it was that it had a vastly lower carbon footprint than the alternatives at the time.

At the time, the characterization of Xbox energy use was that leaving an Xbox running was like leaving your fridge door wide open.  It literally used as much power as the typical American fridge.

That does not appear to have changed in the past couple of decades.  Exactly how much energy a gaming console uses depends on what you’re doing. But it’s clear that running a graphics-intensive game, on an Xbox, and using some modest-sized display, could easily consume 300 watts.  

Here’s a site with a nice table showing typical ranges of energy consumption for home gaming consoles.  In particular, they have a nice table for the PS4, showing that the difference between letting the machine run, unused, and putting it on standby, is about 85 watts.  That matches my recollection for the Xbox.

And, doing just the tiniest bit of math, if you let that game console run at idle all the time (i.e., showing the menu), that will cost you about 750 KWH per year, compared to powering it down to standby mode.  That 750 KWH is, in fact, more than the average U.S. fridge, per year.

The upshot is that, as I recalled, if you don’t enforce turning your Xbox off, but instead just leave it idling, the additional electricity cost is more than the cost of running a refrigerator.

What did Microsoft actually just do?  Sleep versus Shutdown, or about 130 KWH per year in energy savings.

As is typical with modern news-righteousness, everybody seems to start yelling before you can get a clear picture of what just happened.

If you want a clear explanation, start here.

At issue is the difference between Sleep mode (with instant-on), and Shutdown mode (where it takes about 15 seconds for the Xbox to reboot).  Just as with your laptop, one of those keeps everything in memory, keeps memory warm, and uses more power.   The other one writes things off to storage, then more-or-less turns the machine off.

Sleep consumes perhaps 15 watts, while shutdown mode consumes just 0.5 watts. Which doesn’t sound like much, but for an Xbox continuously plugged in, the 15 watt Sleep mode consumes about 130 KWH per year more than the 0.5 watt Shutdown mode.

Just FYI, that’s enough electricity to power my wife’s Prius Prime for about 750 city miles of driving.  At the prices I pay in Virginia, that’s about $15 worth of electricity per year.

In the past, Sleep was the default mode.  But starting in March 2022, Microsoft change the default to Shutdown, rather than Sleep, for newly-manufactured units.  So, to be clear, this new default has been in place for almost a year, on newly-purchased units.

The current controversy arose because Microsoft is updating the software on older Xbox units to make them match the standard that has been in place for about a year, for new units.  That is, they are going to make Shutdown the default.

Users can override that if they wish.

In my experience, you don’t scrape the bottom of the barrel until the barrel is empty.

I don’t know how the party of Teddy Roosevelt ended up being the pro-energy-consumption party.  But that seems to characterize the Republican party today.  Coal is good.  Renewables are bad.  Energy use is good.  Energy conservation is bad.

At root, this is a controversy about a manufacturer choosing to make the software on older gaming consoles match the software that it has put on consoles manufactured for the past year.  Mainly, this changed the default “off” setting from Sleep to Shutdown, which I calculate should save about 130 KWH per year per unit.

Near as I can tell, Microsoft updates the software on my computer any damn time it pleases.  And I actually depend on the computer to get along in the real world.  How on earth this update to gaming-console software became such a cause célèbre among the Right, I cannot even begin to fathom.

But, ultimately, I think it’s a good sign.  If that’s the biggest thing they have to complain about, then things must be going pretty well.

Post #1693: Razor blade wear and tear, the final piece of the puzzle.

 

OK, I lied.  My last post was not my final post on shaving.

To complete the analysis of factors affecting razor blades, I need to document normal variation in beards.  In short:  It’s huge.  All other things equal, that almost certainly leads to huge variation in razor blade life.

This scholarly article will probably tell you more than you ever wanted to know about beard hair.   A key sentence is:

The density of beard hair follicles varies with facial area and ethnicity. Values range between 20 and 80 follicles/cm2

I interpret that to mean that, within normal variation, some guys have four times as many beard hairs (per skin area) as others.  All other things equal, that’s going to generate four-fold variation in razor blade longevity.

There is further variation in hair thickness, stiffness, shape, and so on.

With that much background variation, there really is no such thing as normal razor blade life.   There’s only what’s normal for you, and what you can plausibly do to extend it.

The only shaving technique studied in that article is wetting (hydrating) your beard.  Which I think anybody who shaves with a blade understands to some degree.

The force needed to cut a beard hair is reduced by about 20% within the first minute of water contact. After four minutes, the cutting force is reduced by 40% and does not significantly decrease further with longer hydration

This correlates well with the standard advice you’ll hear from shaving experts, which is to let your shaving soap or cream sit on your face for a minute or two before you shave.  (Both shave cream and soap lather contain water.)

Interestingly, I can find zero scholarly evidence that the fat (e.g., stearic acid) in shaving cream does anything to soften hair.  And yet, I have found that shaving cream extends blade life, compared to shaving with soap, even though both methods result in hydrating the beard prior to shaving.  Moreover, so far (shave #10 on the same blade, today) it extends blade life far beyond what you might expect from the 40% reduction in cutting force cited above.  And, all major brands of shaving cream or gel contain one of two fatty acids as their main component.

Maybe that’s strictly a skin softener?  Maybe a lot of the wear-and-tear of shaving comes from the skin, and not the hair?

Beats me.  Whatever the underlying mechanism is, it seems to work.  And every manufacturer of shaving cream seems to include it as the main ingredient after water.

I guess, now, I really will call it a day on posts about shaving.

That’s not to say that I’ve exhausted the topic.

It’s more than I’ve exhausted my willingness to track down all the nutty claims that are made about shaving and razor blades.  Every time I look, I find another one.  Today, it’s a patent claiming that dipping razor blades in 12% to 20% citric acid will extend their life at least five-fold, by preventing the formation of “mineral crystal buildup”.

Edit:  Well, as it turns out, upon further research, that’s not so nutty after all.  See Post #1699 on how water spots (calcium carbonate deposits, or “mineral crystal buildup”) can coat the razor edge and so dull the blade.

Let us never forget that you can keep your blades sharp forever by keeping them in a pyramid-shaped object.  But only if you orient it exactly with the earth’s magnetic field.  And yeah, there’s a patent for that one, too.

Post #1692: Strop-a-Palooza, the finale. Use a knife steel to strop stainless-steel razor blades

 

Edit:  Nope. See below.  Honing a worn stainless-steel blade with a knife steel made the edges look a lot better.  But the blade still shaves badly.  And I have no idea why.

I think I’ve figured out a possibly-effective way to strop or hone a stainless steel razor blade.  Possibly.  Use a sharpening steel.  The thing pictured at the top of the post.

Don’t use an abrasive (e.g., diamond) steel.  Use a common carbon-steel knife sharpening rod.  The last post demonstrated that you can’t abrade much off the edge before the blade is ruined for shaving.

Use the “pull” technique.   Weirdly enough, half the experts on Youtube pull the blade across the steel.  Half push the blade, as if you were cutting into the steel.  That suggests to me that this works either way.  And pulling a razor blade is going to be a lot easier.  Like this technique (Youtube link).

Hold the blade at very shallow angle to the knife steel.  Start at one side of the edge, and pull it across and up the steel.  Flip and repeat as often as you want, because, based no seemingly expert authority, it’s almost impossible to over-steel a knife edge.

I’m not entirely sure this works, but it’s the best I’ve come up with, and it seems to do something.

For sure, this does nothing for any chips in the blade edge that are large enough to be visible with a microscope.  So if a blade edge is badly eroded, honing it in this fashion isn’t going to fix it.  But, that’s fair, as honing or stropping isn’t supposed to repair a damaged cutting edge.  Those really just clean up the very final finish on an otherwise sound cutting edge.

But, maybe it does something to the very edge of the blade.  After vigorous stropping in this fashion, the stropped edge of a razor blade feels sharper when run across the ball of the finger.  So much so that I can tell one edge from the other in a blind test.

Unfortunately, I have no other evidence that this is actually doing anything.  Whatever is happening at the very knife-edge of the steel is far too small for me to see with my crude microscope.  My home-made sharpness tester had too high a variance to tell me much.  And, with one blind shave test, I can’t really feel any difference in shaving.

Edit:  Finally, after 11 shaves with one Personna blade and Barbasol, I judged the shave to be inadequate.  Here’s a contrast of the worn blade and a new blade, after that 11th shave.  You can clearly see that the new edge is perfectly straight, but that the worn edge has quite a ragged appearance. 

(Parenthetically, you can see what a difference shaving cream makes relative to Dove soap.  Unlike my used blades after soap shaving, on this blade there are no huge nicks in the edge, just an uneven razor edge.)

This amount of edge wear is enough to cause me to change to a fresh blade. 

I did my best to see whether or not the blade was any narrower, per my prior experiment in sharpening a blade.  As far as I tell, it’s not. So I’m not wearing out the blade by making it too small to give a good shave. (If that were true, there would be no point in proceeding, because I can’t restore the blade to its original width.)  I’m wearing out the blade by giving it a ragged razor edge.

So, what the heck.  I carefully steeled/honed that worn blade.  Held the blade in my hand, and gave it about ten strokes across the steel, on each edge, flipping the blade with each stroke. 

Below you see two views of the same pair of blades after passing the worn blade over the knife steel.  By eye, the worn edge now appears somewhat less ragged.  Not perfect, but significantly straighter.  Which, I think, is roughly what a knife steel ought to do.  Clean up the very tip of the razor edge of the blade.

I still don’t know if this improved the blade enough that it can still used.  But I’m going to try shaving with it tomorrow.  (Honestly, it’s hard even to be sure that I’m not kidding myself about the steeled edge being straighter.)  Shaving is clearly going to be a subjective test, and if I’d thought about it, I’d have steeled just one edge, so I could do a blind shave test of one edge versus the other.  But that’s water over the dam at this point.

I’ll re-edit this one more time, after I’ve shaved with the worn-and-carefully-steeled blade.

Final edit:  Still doesn’t shave worth a damn.  I have no idea why. 

The blade remains the correct width.  I pulled out a micrometer, and the worn blade is exactly the same edge-to-edge width as a new blade (to within the 0.01 mm resolution of the tool.) 

The blade edge looks good.  Under magnification (with a cheap USB microscope), the blade edge is nice and straight.  I’m hard pressed to tell the used blade from a new blade.

The upshot is that I have no clue why the blade won’t shave.  Possibly the blade wear goes on at a scale that I just can’t see with my current level of magnification?  I hate to leave it like that, but I can’t see any reason why this blade no longer shaves well.  But it doesn’t.

That said, this brings my razor blade deep-dive to closure.  The final question was whether or not there was anything you could do to re-sharpen a stainless-steel blade.  Edit: My answer is, yeah, maybe.  Try using a knife steel.  As of this writing, my answer is no.  As with stropping on leather, I can use a knife steel to clean up the edge, but I can’t make the blade shave well again.

Finally, I am virtually certain that all the methods you may see on the internet, for stropping a razor blade, are simply folklore.  E.g., rub the blade on the inside of a glass, strop it on denim, and so on.  These probably date back to the era of carbon-steel blades.  I’m pretty sure stainless is just too hard (or wear-resistant) for those to work.

Even a proper leather strop merely shined up and cleaned up my blade edge.  It didn’t make it any sharper or better for shaving.  Experts say that you need to use abrasives, if you plan to strop stainless on leather.  My guess is that this is good advice.  But unlike a knife blade, you can’t afford to lose even a smidgen of metal off the edge of a razor blade, or it will no longer function in a safety razor.  So I don’t think abrasives are the answer here.  But I have to note that I have not actually tried loading up a leather strop with the proper stropping abrasive and having at it.

So, the only other object commonly used for cleaning up the edge of a stainless blade, without abrading it, is a knife steel.  Knife steels definitely work on stainless knives.  There’s no reason to think they won’t work on stainless razor blades.

And, near as I can tell, yes, steeling a stainless razor blade in this fashion does something.  Kinda.  I guess?

So with that, I’m calling it a day.

 

Post #1691: Strop-a-Palooza, Part 3: Fool’s errand?

 

I’m ready to call it quits on trying to strop a stainless-steel double edge razor blade.  For now, at least.

The only thing I’m fairly sure about is that effectively honing or stropping a stainless-steel blade will probably require some sort of abrasive.  But … if I abrade away enough of the razor edge, the blade will no longer function (see prior post).

So it’s possible that this has been a fool’s errand.  Or it’s possible that I don’t have a good grasp of how much damage can and cannot be repaired by honing or stropping a stainless-steel razor blade.

Here’s a sequence of photographs, starting with a beaten-up blade, and ending with a blade that was honed using Brasso, an abrasive metal cleaner.

1: Original condition, note the nicks in the leading edge of the blade

2: After honing in a large-diameter piece of borosilicate glass.  This was a PYREX measuring cup, and best guess, that’s about the diameter that antique glass hones would have matched.  I’m not really seeing a whole lot of change in the nicks.

3: Hone on medium-diameter borosilicate.  I’m certain this was smaller diameter than implied by antique glass razor blade hones.  I’m still seeing no marked improvement in the nicks.

4:  Hone on very mall diameter borosilicate.  Maybe some of the nicks look a bit less sharp.  Maybe that’s my imagination.

5:  Leather strop, dry, 20 strokes of the razor, on 6″ strop.  The surface is nicely polished, but the edge is still a mess.

6:  Extensive honing using Brasso on medium- and small-diameter borosilicate.  The abrasives in the Brasso were evident (it felt gritty to move the blade against the glass), and maybe this smoothed down the nicks in the leading edge of the blade.

Here’s my take on all of that.

Rubbing these blades across any of the tested surfaces, without abrasives, didn’t seem to do much.  Plausibly, there’s something happening to the absolute edge of the blade.  But in terms of smoothing out those (almost microscopic) nicks in the blade, it was no go.  I think that’s consistent with expert advice to use abrasives when honing a stainless straight-razor.

Honing with abrasive Brasso on curved glass maybe did something, maybe not.  Definitely maybe kinda smoothed over some edges on the nicks in the blade.

But, at the end of the day, if you compare the rough, pitted edge in the first couple of photos, to the edge in the last photo, I’m not sure I’ve done much.

Conclusion.

For now, I’m stumped.

First, it’s possible that I simply don’t understand what honing or stropping is capable of doing to the edge of the blade.   Maybe a blade like the one above is beyond help.  In which case, I’m not sure what honing or stropping is going to do for me, for a stainless blade.  Because if the blade is in much better shape than that, chances are it shaves fine.

Second, no wet-shaving experts try to hone stainless blades.  It’s obvious, from reading well-informed discussion on wet shaving forums such as Badger and Blade, that wet-shaving afficianados will, occasionally, strop old-fashioned carbon steel razor blades.  But nobody strops stainless razor blades.  To the contrary, every mention of stainless and stropping/honing boils down to “they last longer, but you can’t strop them back into shape, the way you can with a carbon-steel blade”.  So, not even die-hard wet shaving fans mention any way to strop stainless razor blades.

Third, I already noted that stropping died out when stainless steel took over the blade market.  I am certainly that traditional stropping methods should not work (or work well, or work easily) on stainless, owing at least to the greater hardness of the steel.  Even straight razors — where stainless steel razors can be stropped — require use of an abrasive.  That tells me that traditional materials used to strop carbon steel just won’t cut it.

I’m really left with just two more things I can try.

First, I can add abrasives to the leather strop.  Plausibly, the combination of abrasives and the pliable backing will carry those abrasives into the nicks in the blade and scour them out.

The drawback to that is that the only way I have to strop a blade is to run it over the leather strop while it’s in my razor.  (Even that’s not ideal — I’m pretty sure the razor blade does not sit at the correct angle when I do that.)  In any case, I don’t want to subject my razor to the abrasives in Brasso or similar.  So I need to buy or rig up something to hold the blade, if I do that.

Second, I can buy one of those mystery devices that claims to extend the life of razor blade cartridges.  (reference, reference). Those work by stropping the stainless-steel blades contained in the razor cartridges.  Some people swear they work.  Others say they don’t.  The real question is whether I want to spend $10 on something that I’m betting is a scam.

When all is said and done, if I get motivated, I’ll try one more thing.  I’ll buy or make a device to hold the razor blade at the correct angle, and try stropping with a leather strop and the proper abrasives.

At that point, if that doesn’t do it, then I’m done.  I’ll judge that stropping or honing a stainless-steel razor blade is a fool’s errand.