BU-808: How to Prolong Lithium-based Batteries (2023)(batteryuniversity.com) |
BU-808: How to Prolong Lithium-based Batteries (2023)(batteryuniversity.com) |
My understanding from this article is that:
1. Charge the battery to as low a max percentage as possible (till about 65%) 2. Keep it as cool as possible (up to zero degrees C at least) 3. Use it as little as possible before recharging it (minimize charge-discharge bandwidth)
Aka, over-rate and over size the battery if you're building the device, and minimize extremes on any side of soc (state of charge).
Do EV manufacturers use any other tricks not covered by this?
(Of course, use the device as needed, these are just guidelines for the best perfomance.)
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), which you probably did anyway, and keep the battery between 20% and 80% as much as possible. If the battery is going to stay unused for a while, leave it at 3.8V (or close to it), or at 50%.
Batteries are ultimately consumables, so don't stress too much. Just care for them as much as convenient, and that's it.
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).
> 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.
The worst temperature abuse case is DC fast charging, aka Supercharging, where high current charging creates tons of heat due to resistive losses. This is why frequent fast charging causes faster battery degradation, but ordinary charging and driving does not, because the coolant loop is sized for the DC fast charge heat transfer requirements.
Besides removing heat, adding heat into the system is also desirable. Cold weather environments approaching freezing or below is also bad for battery longevity, and more importantly, terrible for range. Resistive heaters are super power hungry, and to heat the battery coolant loop requires power from the battery. This is why, conventionally, EVs are terrible in cold weather.
> Do EV manufacturers use any other tricks not covered by this?
And now, onto the magic trick.
Heat management is so important to both the driving range and the longevity of a vehicle that EVs have moved from traditional resistive heaters to heat pumps. These magical thermodynamic devices can move heat from anywhere, including drawing heat out of cold ambient air.
When you combine that with a valve design that allows the heat pump to access the battery coolant loop, the motor drivetrain coolant loop, the cabin coolant loop, the vehicle computer(s) coolant loops, and external ambient temperature, you can have a super efficient system that shuffles heat where it's "wasted" to where it's "needed".
Tesla has an excellent video briefly covering their heat pump and their very clever Octovalve design: https://www.youtube.com/watch?v=DyGgrkeds5U
For more depth, this video covers the heat pump and the ~22 different sources of heat it can draw heat from: https://www.youtube.com/watch?v=Dujr3DRkpDU
Automotive EE here. EV aren’t ready for world wide use. That statement is constantly ignored by people in California who see zero issues with their new expensive fancy cars.
Shortest version… The heating and cooling systems of the battery are there to prevent damage. BUT… who powers the heating and cooling systems? The battery of course.
In a traditional or better yet a plugin hybrid, you can use the gas engine to control how much electric you are using in conditions that would be harmful to the battery. In EV vehicles you have no choice. The car won’t tell you “you can’t drive right now”.
The marketing of EVs was a mistake, and every mfg is paying for it. Ford taking a 2 billion write off this year on their EV line and canceling a lot of their vehicles.
They will be cool, but this generation makes a great second vehicle or town vehicle. Absolutely not an extreme weather highway vehicle.
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.
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
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.
I also try to charge fully only just before use (and only if I need 100%), and store at partial charge. If I am charging for storage, I just set a 30 minute timer. Since 1C charging is the most common, 30 minutes at 1C will be about 50% state of charge from empty, which is useful for items with no state of charge indicator.
I use AlDente[1] on my Apple laptops, and the 80% charge feature on my Pixel phone. My bedside phone charger is a slow charger.
Maybe I'm doing too much to manage my batteries, but I also haven't needed to retire anything for having a bad battery in many years, nor had items with dwindling capacity.
[1] https://github.com/AppHouseKitchen/AlDente-Battery_Care_and_...
Source? The common figure for smartphone batteries is "at least 80% capacity after 2 years", and that presumably includes cycles, not just leaving it charged.
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 was glad to see my new Samsung XCover 7 has a built-in option to limit charge to 80%, although a flaky usb cable could sometimes overcharge to 100%. And also has a removable battery.
protected lithium cells are fairly save and easy to replace into devices designed for them. Lifepo4 cells similarly.
We need more product engineers out there fighting the good fight.
“The most Intelligent Battery Health Protection for Phones & Laptops”
https://chargie.org/Don' let the voltage go to far below 3.7V and don't over charge above ~4-4.2V.
A possibility to limit charging to ~65% does not exist per se but you can measure the time it takes to charge from 25% to 65% and use a power timer to shut down charging after that period of time. It's not accurate but easy to implement.
Another factor is fast charging... The battery loses capscity significantly faster if you fast charge often...
I personally only use the 80% limitation...
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.
The charge controller is in the phone. The cable and power supply have no bearing on when charging is terminated. Android has an "optimized charging" option where it will charge above 80% shortly before it predicts you are likely to unplug. Samsung may have meddled with this behavior but that isn't Android's fault.
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...
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.
Shifting the easy 70% first gives a very nice boost, and the rest can be cajoled/fed hydrogen (if it matures by then) etc over time.
I have a vehicle in my personal shop right now. It needs a new battery, it is effectively totaled.
The battery costs more than the vehicle.
The effort for me to replace the battery modules (not even the cells inside of them) involves taking the entire suspension out, and then, you have the ACTUALLY FATAL issue of working on the battery pack. You need 1000V+ gloves that expire every six months, composite ratchets and sockets, and for me high voltage certification.
There is nothing on an ICE vehicle that can kill you while working on its parts.
I will be downvoted by people who need (literally) to defend their purchase. Always am on this topic.
95% would probably work out for you and still decrease battery wearout...
No one is talking about the brakes.
I’m an automotive engineer that has worked for two of the big4. What is your experience?
When I need to drive me EV I open the door, get in, close the door, put it in drive and drive off.
Were you expecting something different? I'm in Norway by the way where it is expected to be -15 C in a few days; after eight years of EV driving (2015 Tesla S 70D) I am not anticipating any problems.
> What is your experience?
I've told you mine, what's yours? Or will you argue from authority again?
>Cool. And when you need to drive it? Most systems do not keep the battery heater running indefinitely.
I get in and put it into drive. When it's cold, I preheat it, I can program departure times, so the battery is conditioned and the cabin warmed in advance. Even at sub-zero temperatures, it always starts reliably, unlike a diesel engine, which, as you know, requires preheating and can struggle with extreme cold starts. Also requires winter diesel.
I see the same reaction with healthy eating, where people are so put off by extremely militant advice that they think "I can't eat only vegetables all day, fuck it, I'll eat these three cheeseburgers".
I agree with your second comment, the first one just could be misconstrued as very hard-to-follow advice.
It's a concern mainly for e.g. offgrid batteries being used in the winter.
You own an EV right?
One sits on my desk at work, one sits on my desk at home and the third sits on my bedside table (it acts like a clock radio / alarm clock). I just place it on the relevant charger while working / sleeping and it's always got enough charge when I need it.
(I also use the surprisingly fairly recent addition of charging protection to limit it to 80% charge)
I'm aware this won't work for all use cases, but it's great for mine.
The only time my phone has given me a message about heat was, indeed, in a phone holder in the car, but it wasn't even charging. We are experiencing a heat wave in Australia right now though, and the car had been sitting in the sun in a car park for an hour.
PHEV is the old term, it's a plug in hybrid EV. I.e., you can plug it in and use the battery, or use the ICE engine via petrol (gasoline).
(B)EVs are pure battery EVs. Think Tesla.
REEV/EREV is range extender EV. Essentially an EV that has a small ICE engine that's very handy for making the 50 or 100km battery "run" for 500km if the need arises, by using the ICE as a generator.
In some countries, you also have "strong" and "weak" hybrids - these are not cars you can plug in (they only take petrol), but they use some motors and battery to vastly improve the efficiency of the engine. Think doubling your mileage levels of good.
> Consumers are just expected to know this stuff somehow, it’s nuts.
Yeah no I don't think that's good design either. May I ask what kind of parts do you buy that makes it so confusing? Our car (Honda) has a very simple model name, there's not a lot of variations or options to confuse to begin with.
Btw, if you want a real fun doozy, look up the parallel series hybrid system that iirc GM had. It was a beautiful beast - it could basically take any power source, and do anything with it (charge battery, run wheels etc). There's a good YouTube video on it if you search for it.
The redditor comment here is sort of a projection. Kind of like ..a redditor mod.
I googled PZEV, and apparently all it means is that it isn't releasing gasoline vapours - other emissions don't matter.
So it's essentially just an ICE engine car that's not super polluting. It has nothing to do with EVs apart from being misleading in its name (perhaps on purpose?).
No.
PZEV means partial zero-emotions vehicle… it is just STAR-STOP.
When you stop, the car shuts off and when it’s off it isn’t emitting anything. That is what it means.
It’s a total scam. Subaru was the first to put a logo on a US government mandated requirement (that made no sense).
But, I figured that the battery would heat up more the faster it's being charged, and so wired charging at the same wattage would heat the battery more than wireless charging.
Must be a lot of power->heat transfer loss with wireless charging.
/s