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Comment by sjg007 | Hacker News Reader

I don't see how electric cars are any different than mobile phones. So basically this means a 3 year life span in terms of battery performance. Regular combustion cars though also suffer reduced mpg so I am not saying this is an apples to apples comparison.

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Common misconception and big reason why many avoid EVs. They are both Li-ion but battery degradation is very much mitigated in an EV because of very close attention to thermal management. Plus warranties on batteries give you something like 70% at ten years I think

With phones and regular usage you are likely doing full charge/discharge cycles every day or two, which is hard on the battery. That's not really the case with electric cars. When you have 200-300 miles of range, and you only regularly drive, say, 20 or 30 miles per day, it's pretty easy to keep the battery around 70%-80%, which should significantly extend the life span.

Obviously the batteries still degrade, but they should be usable long past 3 years assuming regular driving habits.

Electric cars have been around sufficiently long that we already know this isn't the case. Even with these early technology EVs. The only EV with any kind of problem that is sort-of similar to that is the original Leaf.

The reduced mpg is not all that much though, maybe 2-3 mpg nothing nearly as significant as driving behavior on mpg. A small displacement honda is going to have good mpg all its life unless something has really fouled up.

I've noticed a 5mpg decrease with every car I've owned in pretty similar driving conditions over 5-10 years and immaculate maintenance.

That can’t be right, it would leave your cars immobile after like 6 years, and getting half the range out of a tank after 3 years.

Cars are good for 20 years still going roughly as far on a tank as they did. I’ll believe 10% loss of mpg over a lifetime, I don’t track that closely, but 10-20% range loss on a tank per year, nahhh.

Sorry I meant a 5mpg decrease overall not every year. That would fit with the 10% you describe.

I'm driving a 2013 F-150; it's got ~20mpg since I got it in 2014. The 2004 Corvette still gets approx. 30 (mostly highway), although it desperately needs new fuel injectors.

That is not normal. Every car I have owned has maintained its gas mileage unless something was wrong with it. My current vehicle is over 20 years old and is actually getting better gas mileage than it was when I bought it 3 years ago. I do keep up on maintenance more than the average person does tho.

Honestly in my experience, small displacement cars have typically gotten OVER epa estimate mpg. I had a 25 year old acura that got 35mpg easily each tank, epa estimate when it was new was like 30mpg iirc.

While nobody will come out and say it, I’m convinced based on some extensive early career battery system engineering and various evidence from tesla that what they do is put in much more raw capacity than they sell you and then limit with software the capacity of the battery.

Early in the life of the battery this leads to slowed degredation and as the battery agrees the software uses more and more of the raw capacity to make it appear like the capacity is being lost much slower than it is… then at some point capacity will fall off a cliff when the excess is depleted.

Comparable to how SSDs have capacity reserved for bad blocks.

It is probably good engineering but it would be nice for the mechanics to be sold truthfully and some level of control to be given to the owner.

I mean, you don't have to guess. There are plenty of battery teardown videos where they count the cells. IIRC it's on the order of 5-10% kWh reserved.

Wouldn’t this be extremely easy to find out with a battery tear down/test?

I mean the Chevy Volt uses only 50% of it's battery capacity but it can more easily do that thanks to having a built-in gasoline engine that operates more like a generator for the electric engine. When I found out that they limited the battery for maximum longevity I was less stressed out about the battery life. They still degrade over time and until they become more modular like the Ultium system GM is putting into their next-gen EVs it's still a big costly single point of failure.

It's not as high as 50%.

GM also does this with the Bolt and Volt. I was under the impression that Tesla did this less so.

This is clearly the case as every time there is a mass evacuation from somewhere they issue an OTA update to release more battery capacity.

I'm pretty sure every product with lithium-ion batteries does this, but it's not so that they can use the extra capacity later, it's because letting these kind of batteries either fully charge or discharge is itself harmful to the batteries, so to get a useful lifespan you have to have some amount of extra capacity.

A friend with a 6yo P85D says his battery performance is still in the high 80%s vs brand new. What to do with large numbers of EVs at the end of their useful battery life is still an unsolved problem though.

At least with a car you might be able to replace the battery. Maybe. Of course the auto companies have the same incentives as the mobile phone companies to want you to replace the whole thing.

It's pretty easy to replace phone batteries, I wish people would stop spreading this myth. Popular models can nearly al be done by somebody that could change their own oil in a car. And there are phone repair shops in nearly every town for those who want to spend $20-$50 to have a pro do it.

Please don't discard a phone merely because of a bad battery, unless you've tried to get a replacement!

So, just like a phone then? Those batteries are also replaceable, even if they aren’t user-replaceable.

https://support.apple.com/iphone/repair/service/battery-powe...

Most phones use LiPo Batteries not LiIon, so they're not directly comparable. Afaik LiPo is known to have a lower lifespan.

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