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

https://www.batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries/

by eswat • 6 months ago

74 64 6 months ago

JamesTRexx• 6 months ago

After the first battery of my Samsung S4 expanded at the end of its life in less than 2 years, I found a utility that didn't work perfectly but could limit charge anywhere between 30 to 100% most of the time, and it prolonged the lifetime of the couple of later batteries during the 10+ years I used the phone with a limit around 66%.

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.

Mistletoe• 6 months ago

You only charged your phone to 66% for ten years?

gattilorenz• 6 months ago

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.

vladvasiliu• 6 months ago

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...

sandreas2• 6 months ago

It's probably not a flaky USB cable. Androids charging limit of 80% includes a policy to charge 100% every 14 days to recalibrate the battery controller.

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...

avidiax4• 6 months ago

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.

kevin_thibedeau• 6 months ago

although a flaky usb cable could sometimes overcharge

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.

user_78328• 6 months ago

+1 for battery university, they're an excellent source. Does anyone have any other suggestions for similarly technically deep (while approachable) articles on any other facet consumer electronics?

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.)

stavros5• 6 months ago

I don't think this advice is useful. 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 (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.

user_78328• 6 months ago

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.

VorpalWay• 6 months ago

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).

SV_BubbleTime6• 6 months ago

Do EV manufacturers use any other tricks not covered by this?

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.

user_78328• 6 months ago

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.

pengaru• 6 months ago

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

kuerbel2• 6 months ago

...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

ninalanyon2• 6 months ago

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

s-y2• 6 months ago

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.

HPsquared• 6 months ago

Light bulbs (including LEDs) are similar. If you use them at slightly lower then their maximum rating, things tend to last a LOT longer. The "Dubai lamp" uses this concept - oversized LEDs that are derated, and last a very long time (100k hours). You can do the same by buying oversized dimmable LEDs and simply turning down the brightness.

butvacuum• 6 months ago

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

averynicepen2• 6 months ago

Degradation is driven by many things, but a big one is heat. Elevated temperatures during both charge and discharge is very bad for battery longevity. To manage this, almost all EVs use liquid cooling, with a cold plate directly contacting as many battery cells as they can to move heat out of the battery. This coolant is then cooled by a radiator, an AC chiller, or both.

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

bullen• 6 months ago

Between 50% 3.7V and 80% ~4-4.2V is the best.

Don' let the voltage go to far below 3.7V and don't over charge above ~4-4.2V.

notherhack• 6 months ago

Reminds me of “Chargie”, a gadget that goes inline with your USB charging cable and controlled by an app on the device to limit the charge level to whatever you choose. I think it was born via kickstarter.

  “The most Intelligent Battery Health Protection for Phones & Laptops”
  https://chargie.org/

avidiax4• 6 months ago

I may be a bit odd, but I store lithium ion battery containing electronics in the vegetable drawer in the fridge. You lose 20% of capacity in a year if you have 100% state of charge but only 6% loss of capacity at refrigerator temperatures. So tool batteries, small electronics and whatever else that isn't used weekly gets put in.

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_...

gruez• 6 months ago

You lose 20% of capacity in a year if you have 100% state of charge but only 6% loss of capacity at refrigerator temperatures.

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.

avidiax4• 6 months ago

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.

averynicepen2• 6 months ago

Have you ever measured your battery voltages over time storing it this way? Is that 6% capacity loss theoretical or measured data? I'm intrigued. This sounds crazy, but it should technically be fundamentally sound.

avidiax4• 6 months ago

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).

greentea23• 6 months ago

One of the biggest reasons I still prefer to root my phone is to use acc https://github.com/VR-25/acc. It's criminal that you have to root to run code that reduces charging speed or shuts the phone down automatically. I have it shut down at 20% and charge to 80% except when I know I will need to be out for an extended period without a charger.

1970-01-01• 6 months ago

Note that the title is slightly misleading. If you didn't know, lithium-based could mean lithium phosphate, lithium titanate, or lithium ion (or other lithium chemistry). This guide is targeting lithium ion cells.

CrimsonCape• 6 months ago

It's unfortunate that there is huge interest in prolonging lithium battery life because it's an indication of products with hard-to-replace batteries.

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.

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

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