+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.)
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.
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".
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.
> 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.
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.
>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.
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.
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.
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...
> 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.
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.
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/
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.
user_7832|1 month ago
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.)
stavros|1 month 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), 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.
averynicepen|1 month ago
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
HPsquared|1 month ago
SV_BubbleTime|1 month ago
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.
avidiax|1 month ago
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|1 month ago
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.
averynicepen|1 month ago
JamesTRexx|1 month ago
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.
sandreas|1 month ago
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...
kevin_thibedeau|1 month ago
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.
Mistletoe|1 month ago
greentea23|1 month ago
CrimsonCape|1 month ago
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.
notherhack|1 month ago
1970-01-01|1 month ago
bullen|1 month ago
Don' let the voltage go to far below 3.7V and don't over charge above ~4-4.2V.