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EV Batteries Are Defying Expectations After Miles

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Re: EV Batteries Are Defying Expectations After Miles

#81

Post by VBprogrammer »

squidbeak wrote: post #67
VBprogrammer wrote: post #45

Earlier quoted context omitted.

That's easy to say when you aren't the one considering adding a huge liability to the companies bottom line. There are also some elements of EV ownership where they require some TLC, like not overcharging them when doing mostly local journeys, not using rapid charging more than necessary etc. If manufacturers were carrying the can it would be easy to let these things go out of the window.

> That's easy to say when you aren't the one considering adding a huge liability to the companies bottom line. Obliging companies to make repairable products? Removing their right to lock everyone into disposability and overconsumption? And even worse - trimming a sliver of their profits? Damn right, buddy: we can't be having that.

Those are completely orthogonal to accepting all of the risk, from the point of view of a CEO, of battery failures for cars you sold 10 years ago.

But yes, making things repairable is really important. And, I certainly have concerns that the danger of high voltage batteries will soon be used to introduce so much regulatory burden that it becomes impossible for individuals and small companies to repair them.

Re: EV Batteries Are Defying Expectations After Miles

#82

Post by Taniwha »

dzhiurgis wrote: post #71
Taniwha wrote: post #51

Earlier quoted context omitted.

The original Prius batteries can easily have individual cells replaced (mine is 20 years old, we've replaced 2 cells) - of course Toyota want to sell you an entire battery, the wrecker will sell you a whole bunch of spares (do this with care, an entire pack is hundreds of volts)

Generally you can't replace cells unless you find perfect match - needs to be same resistance and capacity. Only on very large scale this is possible. That said on most EVs blown cells are very very very rare. Mostly it's balancing lead that looses contact.

These are NiMH cells (7V) wired in series (not parallel so matching is less of an issue) - one bad cell and the series resistance of the whole string is shot

Re: EV Batteries Are Defying Expectations After Miles

#83

Post by rsync »

Tadpole9181 wrote: post #75
rsync wrote: post #72

Earlier quoted context omitted.

“They can't realistically do anything else to estimate it …” Of course they can. How do you think they get the MTBF for hard drives? What they do is deploy thousands of them and wait for the first one to fail. Then they wait for the second and third ones to fail… And then they can construct a statistical abstraction for the entire population based on the very first degradations … and that doesn’t take long at all.

If they want to avoid confounding variables to real world use, this could take years. Nobody wants to wait years after an innovation to sell their product, so they develop ways to speed up the testing and get a number. A machine that presses a keyboard switch 500 times a second for several days straight is obviously not indicative of someone actually using the keyboard. But it'll get the "absolutely beat the snot out…

No, it doesn't take years and the testing is performed, roughly, as I just described it.

They build a test rig with 10,000 drives which they run continuously producing a total "drive hours" count and then wait for the first one or two or ten drives to fail.

X failures / 10,000,000 drive-hours will give you your MTBF, etc. ... and only takes ~40 days given a 10k drive test rig.

Some pictures from Seagate lab in Longmont:

https://cdn.mos.cms.futurecdn.net/yHqDagRDz9H5koWBefi24K-120...

https://cdn.mos.cms.futurecdn.net/EiZ9tA6p3UbaJFTaW75JdN.jpg

Re: EV Batteries Are Defying Expectations After Miles

#84

Post by Lio »

Theodores wrote: post #54
raychis wrote: post #31

EV batteries may be lasting far longer than most buyers expected but are consumers really going to trust the data over the headlines? There has been such a propaganda attack on EVs that it will take a long time to overcome that.

Although I have had rechargeable batteries in gadgets for decades, I would not like to have an EV parked in a garage beneath my bedroom, juicing up with many kilowatts, every night. No amount of fire exits would help, I mean, what about my stuff?!? No amount of insurance would cover personal belongings that could get lost, so that means stress from the stupid EV. The technology might be generally proven (the EV could…

No one throws Duracell during riots for a reason. Where as a small bottle, half filled with petrol, and a lit rag makes a pretty good anti-tank weapon.

A car with a tank full of gas is basically a big bomb.

I'd rather sleep over the electric car.

Re: EV Batteries Are Defying Expectations After Miles

#85

Post by timbit42 »

dzhiurgis wrote: post #71
Taniwha wrote: post #51

Earlier quoted context omitted.

The original Prius batteries can easily have individual cells replaced (mine is 20 years old, we've replaced 2 cells) - of course Toyota want to sell you an entire battery, the wrecker will sell you a whole bunch of spares (do this with care, an entire pack is hundreds of volts)

Generally you can't replace cells unless you find perfect match - needs to be same resistance and capacity. Only on very large scale this is possible. That said on most EVs blown cells are very very very rare. Mostly it's balancing lead that looses contact.

I replaced some of the NiMH cells in my Prius traction battery by buying some Prius traction battery cells on eBay for $20 each. Still working fine after 2 1/2 years and a lot cheaper than buying a refurbished traction battery for $3,000. My Prius is 2006 so any cells from the Gen II models (2004-2009) work fine.

Re: EV Batteries Are Defying Expectations After Miles

#86

Post by apparent »

beAbU wrote: post #80
apparent wrote: post #77

> EV batteries aren’t without their challenges, though. A battery that is frequently fast-charged with high power loses its range, on average, at twice the rate of a battery charged at a lower power, according to telematics company Geotab. I wish my car could charge at different rates depending on whether I'm going to need to use it again soon. If not, it could trickle charge and be full enough by the next morning.

Does you EV not have a charge rate setting for AC charging? Or do you want such a feature when DC charging?

I charge over AC at home but just wish that I could specify the rate by telling the car/charger when I'm next going to need the car.

Re: EV Batteries Are Defying Expectations After Miles

#87

Post by apparent »

Lio wrote: post #84
Theodores wrote: post #54

Earlier quoted context omitted.

Although I have had rechargeable batteries in gadgets for decades, I would not like to have an EV parked in a garage beneath my bedroom, juicing up with many kilowatts, every night. No amount of fire exits would help, I mean, what about my stuff?!? No amount of insurance would cover personal belongings that could get lost, so that means stress from the stupid EV. The technology might be generally proven (the EV could…

No one throws Duracell during riots for a reason. Where as a small bottle, half filled with petrol, and a lit rag makes a pretty good anti-tank weapon. A car with a tank full of gas is basically a big bomb. I'd rather sleep over the electric car.

I can't remember an automaker ever doing a recall for an ICE vehicle that would spontaneously combust while parked. Maybe it happened at some point (ICE vehicles have been around for a long time), but there have been several for EVs. The probably is undoubtedly caused in part by the fact that EVs are charged while parked, whereas ICE vehicles are generally just sitting there, turned off.

Re: EV Batteries Are Defying Expectations After Miles

#88

Post by cgyvbunji »

gnfargbl wrote: post #35
y1n0 wrote: post #11

Earlier quoted context omitted.

Not OP, but this talks about it: https://www.sciencedirect.com/science/article/pii/S2352152X2...

That article says calendar ageing was the dominant ageing mechanism for batteries in their test vehicle, because said vehicle spent 96% of its life stationary. Unless I'm missing it, the article doesn't put a number figure on the rate of calendar ageing. Real-world observations suggest batteries are likely to be serviceable for around 20 years, which is around the same lifetime of an average ICE car. Users who can to…

It's not clear how much of a factor calendar age degradation is in EVs because almost nobody is straightforward about it like they are in the battery industry itself.

Re: EV Batteries Are Defying Expectations After Miles

#89

Post by dzhiurgis »

Taniwha wrote: post #82
dzhiurgis wrote: post #71

Earlier quoted context omitted.

Generally you can't replace cells unless you find perfect match - needs to be same resistance and capacity. Only on very large scale this is possible. That said on most EVs blown cells are very very very rare. Mostly it's balancing lead that looses contact.

These are NiMH cells (7V) wired in series (not parallel so matching is less of an issue) - one bad cell and the series resistance of the whole string is shot

kia ora. interesting to know. so they are pretty small packs and their design doesn't really apply to large packs.

Re: EV Batteries Are Defying Expectations After Miles

#90

Post by dzhiurgis »

stavros wrote: post #42
JumpCrisscross wrote: post #41

Earlier quoted context omitted.

It’s a niche, small-volume market. I would be shocked if novel industrial battery chemistries are reaching it within even years of the frontier. (Less surprising would be small-batch novel chemistries. But these aren’t really comparable to the industrially-produced thing.)

We mostly use the same 18650 cells everyone else uses for everything, it's not like we're waiting for custom batteries.

IDK I rarely see 18650 cells in RC. It's mostly pouches which I assume come from smartphone/laptop industry - these are likely to have highest margins and highest tech (other than space).
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