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Discussion in 'Hyundai Kona Electric' started by apu, Jul 26, 2019.
Why worry about things you can't control. Buy insurance be happy
The burn list has been somewhat updated
Scores as follows:
Tesla (S and X) - 21
Hyundai Kona - 4
Now in a solid second place
We is hot on the trail of #1.
Leaf other cars behind!
Does anyone know if all fires occurred while plugged in? Per the manual, I set my recharge to 90%.
But, did the battery fire start before or after the propane tank exploded?
Per the manual what? Are you saying the owner's manual instructs you to charge to 90%?
Well would you look at that, apparently it not just Teslas and Konas that can cook off in garages https://electrek.co/2020/02/17/pors...v090QLFCkDBUo6YRWi_xWTypiCDkug_GiScLBw25CQzto
OK, EVSE inside, car stays out during overnight charge. It's why the cable is 20'. Small price for peace of mind.
Anyone find results of investigations yet?
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To be fair, it's too early to know the cause of the fire. It's entirely possible it wasn't the car. If the EV charger was recently installed, then it's probably more likely it was an improperly installed EV charger that started the fire than a battery fire that started in the car.
BEV owners would do well to pay a licensed electrician to check out the house wiring circuit and make sure the charger is installed correctly and safely. And note that not all people hiring out as electricians are licensed, so do ask.
I just did an admittedly non-exhaustive search of my US manual and I cannot find any reference to charging to only 90%. Every paragraph I found talked about charging to 100%. I know 80% is the "suggested" cut-off when DC fast charging but that's a different story.
Did anyone ever find a report from transport Canada or Hyundai about what they found in their investigation?
Transport Canada said they would provide more information a week after it happened and I never saw anything.
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Yeah, I don't think there's anything in the manual. The "don't charge to 100%" advice seems to be based on some general advice for lithium batteries, but Hyundai doesn't seem to share that concern. Perhaps that's because Hyundai has built in invisible battery capacity, to provide overhead protection (meaning 100%SOC isn't actually 100%), or perhaps because their testing has shown that charging to 100% doesn't appreciably affect degradation. I've chosen not to worry about it. We mostly plug it in to the L1 charger next to our house, which generally gets it to 60 or 80% most nights. Then whenever we need 100% or whenever it comes home with a low charge, we plug it into the L2 charger in the garage. It probably gets a 100% charge about once a week, but mostly is between 50 and 90%.
Based on what I found, on a new Kona Electric, 100% means 95.3% actual charge level based on the assumption that the often mentioned 67.1kwh is the true battery capacity of the Kona. 3.1 kwh extra is 4.7% additional capacity.
I don't expect anything soon from Canada's TSB vs the US NTSB, which tends to give an early likely cause (if they know). I am a pilot so have followed these for a long time. In Canada, the best you get early is the basic facts, weather, location, time, souls on board, route/trajectory/speed, some witness accounts (if credible), etc. You will get more from police reports, and often sensational/inaccurate speculation by news reporters.
Normally it takes 2 years for the TSB to file their report, and even then they will not lay blame. And are very cautious about determining absolutely the cause, usually just giving the facts to let others decide (litigators). So with the Kona fire in Montreal, I don't expect to hear from them for some time yet, and won't hold my breath then for any meaningful or enlightening information. This is not an area where the TSB (or anyone) has much experience, so they will be very conservative with what they publish.
The "charge to 80%" advice originated some years back from home solar power system owners using stationary li-ion batteries for backup storage, as the best "bang for the buck" strategy, getting the most use out of the battery without wearing it out prematurely, in daily cycling.
It's been used as a rule of thumb for BEV advocates too. But please note that "80%" is 80% of the full capacity of the battery pack. What the BEV maker reports, and any owner's manual states, is probably going to refer to usable capacity. That is, the full capacity minus the reserve capacity that all BEV makers "bake" into their battery packs, to prevent premature rapid aging of the batteries under daily cycling.
Now, whether that advice from years ago is still applicable to li-ion batteries found in cars sold in the past few years, I don't know. Perhaps newer battery chemistries hold up better when charged to ~90% or so in daily cycling. Or perhaps BEV makers are now "baking into" their battery packs, a 15% or more reserve, so that what the car reports as a "100% charge" is actually an 85% charge.
Not all battery chemistries are the same, not all BEV makers take the same strategy in choosing reserve capacity, and perhaps some BEV makers are willing to accept more loss of capacity over time than others.
Furthermore, the lower your daily charge level, the lower your range is going to be. So while one could argue that the "best" strategy for preserving long battery life would be to charge the car only to 60% and never discharge it below 40%, that would leave the car with such a short range that it would be impractical for most drivers.
So it's hard to give general advice about daily charging strategies which apply to all BEVs and to all drivers. Also, both battery makers and BEV makers keep the exact characteristics of their batteries as trade secrets, so it's hard to know if li-ion batteries have really improved so much that charging them to 85% or even 90% is now just as good as charging older batteries to 80%. How would we know if this was true? And even if it were true about one model of BEV, it may not be for another.
Anyway, the old advice of "charge your BEV to 80% unless you're planning on driving a long distance the next day" is still good advice, altho perhaps that should be modified to 85% to allow for the expected reserve capacity. It's certainly not going to hurt anything to charge your car to a lower level, so long as that still leaves you with sufficient range for the next day's drive, with of course a bit of safety margin so you don't get into that "range anxiety" mindset. It probably won't hurt, and maybe it will help preserve more of your car's full range for as many years as you want to own it.
The other kicker is, if the BMS does either any top-balancing at all or
even re-establishes its internal concept of "full" at whatever constitutes
100%, then going to that point once in a while lets that happen. Like
right before a decently long trip.
But if the "buffer" margin is sufficiently large, maybe the true SOC never
even gets to that point??
I've seen a lot of arguments, and a lot of claims from self-described experts on both sides of the argument, whether or not charging a battery pack to 100% actually causes the BMS to do any more "balancing" of the pack than it normally does. But I've never seen any convincing evidence that this ever does anything more than, at most, recalibrate the BMS's estimate of the remaining full battery capacity and range of the car.
In case that's not clear, I'm suggesting that, perhaps, all this accomplishes is merely adjusting what the car's software "thinks" the full range is, and doesn't actually have any impact at all on the car's real battery capacity or range.
Seems to me that Occam's Razor shaves in the direction of a well-designed BEV's battery pack always doing balancing every time it charges, and that the "discharge to below 10% and then charge to 100%" procedure, supposedly as a method of "balancing" the battery pack, only stresses the cells unnecessarily. Seems to me most likely that, if anything, repeatedly doing that that will cause the pack to prematurely age... exactly the opposite of what supposedly "re-balancing" the pack is intended to accomplish.
Even if there is something to this business about discharging to less than 10% and then charging to 100% as a method of "re-balancing the pack", it certainly shouldn't be done more than once every 3 months, according to those "experts" who do recommend it. Those who recommend doing so on a monthly or weekly basis, or recommend doing it before every long drive, simply don't know what they're talking about.