BU-808: How to Prolong Lithium-based Batteries (2023)

> I think good advice is to keep your devices as cool as you can (ie don't leave your cars in sunlight when there's shade),

In some climates, such as where I live, the larger issue is the cold in the winter. From what I understand, Li-ion batteries don't like being charged below 0 C. And it is not uncommon for it to dip to -15 C or even -20 C here.

Really, from what I understand, batteries want to be kept above freezing but cool. So yeah, don't leave it in direct sunlight in the middle of summer. The more difficult problem is the winter (unless you happen to have a heated garage).

> You're going to use your devices, so you won't control the temperature or, largely, the charge percentage.

> I think good advice is to keep your devices as cool as you can (...), and keep the battery between 20% and 80% as much as possible.

Yeah that's kinda what I meant. Where it's easy or possible to do so (for eg lots of modern laptops & phones allow charge limits), it's better to follow these guidelines.

> Batteries are ultimately consumables, so don't stress too much. Just care for them as much as convenient, and that's it.

Yeah I agree (and that's what I meant by my last sentence), however, a lot of people (including eg my dad!) end up having battery issues while being unaware that they can do things to protect their hardware.

For example, my phone has enough capacity to last the whole day even at 60% of it's capacity. I've set it to stop charging at 80% (the lowest possible SOC) for this reason. On my laptop, I frequently reduce it to 60% as I use it plugged in.

> I don't think this advice is useful.

I'm afraid I don't get what's not helpful? We're probably talking across each other.

That doesn't help nearly as much as reducing the current through them. And, PWM doesn't change the lumens per watt at all.

Are you a technician or an engineer? And as a follow up, what part of the vehicle do you engineer?

Because this sounds a lot like a case of a dentist seeing a lot of cavities and making conclusions that teeth are "bad tech".

I live in a climate that's in yearly flux from -20 to +35 C and EVs have been normal here for a long time(7+ years) with no major issues. What parameters and therefore regions does your statement cover? I'm sure you can't run an EV in Syberia(RU), but people with petrol cars there have to run them even parked to avoid freezing during the winter so there will always be extremes.

As for the commercial equation: BYD and Tesla don't seem to be fitting that narrative. So this is not a matter of a marketing mistake - but an overall execution on the failed manufacturers.

They seem to be working just fine here in snowy Norway.

...what? You leave your car plugged in, and that's it. Then the BMS will take care of the battery without having to use it's energy.

If I preheat the car it also preheats the battery. If it's not warm enough it won't allow full recuperation. Oh my god, I have to use THE BRAKES for a few minutes, literal trash car.

And all those people in Norway, you know, with their heat pumps and EVs. Obviously life just grinds to a halt there every winter. *dramatic eye roll

How is this not an instance of "perfect is the enemy of good enough?"?

> EV aren’t ready for world wide use.

Fully agree (I'm 100% team PHEV or EREV/REEV) as a mechanical engineer. IMO BEVs and PHEVs/REEVs should be on parity in terms of tax/govt incentives, while encouraging electric use - for eg, subsidized (PH)EV charging, high(er) costs in city centres if running in ICE mode, etc.

I was just curious if EV manufacturers use any other tricks that're "well known" in EV-land but not for the average consumer.

From the article, Table 3: 100% SoC @ 25°C leaves only 80% of the original capacity after a year.

It's easy to look at that table and think that it's remaining charge after a year; it's not. It's lost capacity.

This is known in the industry as "calendar aging". So far as I know, stockpiles of lithium ion batteries are stored at a relatively low state of charge and in a cold environment for this reason among others. It's common to order a laptop battery or similar and get a unit that was manufactured a year back. It would be terrible to get a new battery that already had diminished capacity, which is what would happen if you stored them in a non-conditioned warehouse in a hot climate.

I haven't, and it wouldn't be the voltages. You would have to do a rundown test and see what the effective capacity is (watt-hours).

Maybe I just expect too much battery life, but I find that I get quite low or even run out when I limit charging to 80%.

My feeling is that the coulomb counting on the Pixel 8 Pro is just not very accurate, so the phone thinks it's at 80%, but is really at 60% or 40%.

I still use the feature, but now I have to top up during the day every so often. I suppose rationally I should just charge to 100% rather than take a medicine that causes the same side effect as the disease its meant to treat, but I'm not that rational.

I definitely would do that if I could. I would absolutely love to tell it to only charge to 66% (or whatever, even 50% would work). I rarely use the phone for multiple hours at a time without access to power, and when I do, I usually know beforehand (like during a trip or something) so I could tell it to charge all the way. My battery rarely goes below 80%, even now that the phone is 3.5 years old.

I understand newer iphones now have the option to only charge up to a certain percentage. Mine doesn't have that, it only has the "smart charging", which tries not to charge it too quickly and only is full by the time it expects you'll use it (usually in the morning). It's very hit and miss for my use patterns, so it ends up at 100% most of the time...

Veeeeery slow charger :)

But yeah, at some point we should also consider the tradeoff between convenience and battery life. Batteries can be replaced, having to charge twice a day is a PITA for me.