7/5/2026 at 6:54:08 AM
No manufacturer is testing the batteries life by just charging and discharging them daily for a decade before releasing them. Instead they are using artificial acceleration techniques like getting the battery hot while charging/discharging continuously to simulate a longer lifetime. They can't realistically do anything else to estimate it. But it turns out heat is the big enemy for li-ion batteries and if you can keep them on the cooler side of their range they will last a lot longer.by PaulKeeble
7/5/2026 at 4:11:56 PM
“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.
by rsync
7/5/2026 at 4:50:05 PM
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 of it" number, which is usually good enough for marketing.
by Tadpole9181
7/5/2026 at 7:40:20 PM
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
by rsync
7/5/2026 at 9:21:59 AM
we have EVs for almost 15 years now, one would imagine some real world data on battery life was collected already, even if not widely sharedby memoriyato3
7/5/2026 at 10:04:47 AM
There was and publicly available, although the mainstream press mostly chose to ignore it.My VW hybrid is just over 10 years. The advertising claimed 28 miles on a charge, but the reality was about 18 maximum, with stop-start somewhat less. After a couple of months when it had calibrated, it settled displaying 21 miles for a full charge. 10 years on, and it still reads 21 miles on a full charge, but the reading is less useful in use. It's common for it to drop from 21 to 15 miles after a mile, but to stay on 1 mile remaining for around 4 miles travelled. But essentially, I don't consider the range to have deteriorated too significantly, it still feels around the same ballpark.
A lot of the original thinking about batteries comes from the Nissan Leaf, introduced in 2009, when they guessed that batteries would probably need replacing after 10 years. However, from the cars that were written off from accidents, they discovered much less battery wear than predicted, and around the time I bought my car, they were suggesting batteries would be around 80% after 10 years and most manufacturers started using that figure. I'm not sure what current estimates are, but I wouldn't be surprised if it was closer to 90% after 10 years.
It's common knowledge amongst owners that range is significantly reduced in cold weather - I'd guess from my use, maybe 20% less range on a cold winter day compared to summer.
And as to why car batteries last so much longer than e.g. phone batteries, I think it's mostly because their charging limits are much more pessimistic. Typically a car charger won't ever charge beyond 90% capacity or discharge below 10%, and this is built into its estimated range (so 0 miles remaining is 10% charge).
by ralferoo
7/5/2026 at 10:54:25 AM
I have enabled "charge up to maximum 80%" setting on my phone from day 1, and 2 years later the battery lasts noticeably less. maybe it would have been even worse without that setting.by memoriyato3
7/5/2026 at 12:08:14 PM
YMMV. Likewise, I've been using charge to 80% from the start, the phone is approaching 5 years, and I can't say I'd notice the battery being any worse from new.Bigger issue is that it's been out of OEM updates for 3 years now, which is complete balls considering it's a reputable brand and came with "Android Enterprise Recommended" or whatever that was.
by jusssi
7/5/2026 at 11:41:06 AM
I wonder if it's because phone thermals are way worse so always heating up?by Fire-Dragon-DoL
7/5/2026 at 9:48:44 AM
Battery chemistries have changed and technology has improved a lot in that time frame. Those 15 year old Nissan Leafs have terrible battery degradation, because they're not liquid cooled (hot = bad) and used batteries that degrade fast (LMO, which autocorrect thinks should be spelled LMAO). Manufacturers learned their lesson and every EV built in the last 5 years is far better on both counts.by decimalenough
7/5/2026 at 2:32:42 PM
The only thing you can fault them for is for how long it took to switch to liquid cooled.The leafs are fine cars but you're paying for being an early adopter. I bought one used in 2016, used it as a daily commuter till 2025 and then sold it. I don't think any car will ever be as cheap to run as that one....
by hvb2