Useful Battery Tips

[hmp10]

"Engineering Explained" recently posted a very good overview of how to increase the service life of your EV battery pack:

 

[HariK]

Good video but meant for techies. My wife who is a non-techie, figured out something simple. She drives typically 20 miles a day. Her car Ioniq 5 averages 4 miles per kWh given her driving monthly is about 70% surface streets and 30% highway and she drives at speed limit. She needs about 140miles a week. That is 35kWh or 45% battery in her car. So she can charge to 80% and then again charge when it dips to 35% knowing that the lower limit to prevent the 12V battery from not charging is 20%. 15% is 45 miles of range which is 2 days for her. She then noticed that charging from 35% to 80% on a typical EA charger was taking about 25min in her case. Then she looked at EA chargers close to her daily routine and decided that she can charge 2 times a week just 55 to 80 in less than 20 min of shopping. Her thinking was simple. She rarely needs more than 35% of battery for her longest drive. 55% to 20% is that. She has no more range anxiety and interesting that the video basically says that she is doing the right thing!

 

[hmp10]

Good video but meant for techies.

Yes, it does give the technical reasons for how batteries are best treated a certain way. But each segment ends with a straightforward "do" and "don't" to minimize the type of damage covered in that segment.

And the final wrap-up was simplicity itself: on a daily basis, set your charge limit around 75%; if you have home charging, keep the car plugged in at all times; and if you need to charge the battery fully to prepare for a trip or while on a trip, don't worry about it . . . as long as you don't let it sit at full charge for a prolonged period.

About the worst thing you can do, as least regarding the factors that are in your control, is to charge the car fully at a Level 3 charger, then park it at home, driving it for daily use until you run the battery down low, and then return to the Level 3 charger to do the same thing all over again.

 

[Buffalo Bob]

I'm visiting my daughter, and just hooked up my Pure AWD to her Chevy Bolt charger. The car was already at around 75%, but I thought I would try charging it to 100% for the first time. I know that infrequent charging to 100% is not too hard on the car; and probably especially so when only charging at 7 kW, but I vaguely recall reading that an occasional 100% charge can be good, in that it helps re-calibrate the battery management system for more efficient high-speed charging. (I tried asking about that on the web, and had no luck.) Also, I figured that seeing the range miles when it stops charging and comparing that to the EPA's 410 mile max for the Pure AWD will help me determine the level of battery degradation. Are those two things correct? Thanks!

Just editing after posting. Did find the note endorsing the BMS re-calibration!

 

[DeaneG]

I'm visiting my daughter, and just hooked up my Pure AWD to her Chevy Bolt charger. The car was already at around 75%, but I thought I would try charging it to 100% for the first time. I know that infrequent charging to 100% is not too hard on the car...

Just try to avoid letting the car sit at 100% for long periods of time, especially in a hot environment.
Cars have varying battery chemistry and BMS design. It's best to listen to the advice given by Lucid for Lucid cars rather than some other advice given by another manufacturer.

 

[Buffalo Bob]

Thanks for the advice. The car charged to an EPA range of 409 miles when fully charged, so degradation looks good. I drove around enough to get it down to 97%. I'm in Seattle right now, so it's only in the 70s.

 

[Buffalo Bob]

Thanks again, @DeaneG!

 

[Adnillien]

The BMS calibration with charging to 100% is only helpful for LFP batteries. LFP batteries have a very flat voltage profile over SOC so it is difficult to determine SOC from voltage. Lucid uses NMC batteries that have a much greater voltage variation over SOC and 100% SOC is not needed for calibration. Most cars use a combination of Coulomb (electron) counting and battery voltage to determine SOC. The voltage method has errors when the battery is being used and Coulomb counting has errors in the measurement itself that build up over time. Hence, the recommendation to occasional 100% charge LFP batteries.

 

[Buffalo Bob]

The BMS calibration with charging to 100% is only helpful for LFP batteries. LFP batteries have a very flat voltage profile over SOC so it is difficult to determine SOC from voltage. Lucid uses NMC batteries that have a much greater voltage variation over SOC and 100% SOC is not needed for calibration. Most cars use a combination of Coulomb (electron) counting and battery voltage to determine SOC. The voltage method has errors when the battery is being used and Coulomb counting has errors in the measurement itself that build up over time. Hence, the recommendation to occasional 100% charge LFP batteries.

Well, I'll be darned. Seems I learn something new about this car every day. (That, or I promptly forget and have to learn again.) Thanks, @Adnillien!

It was kind of fun to see the 400+ mile range show up on my display for a change, even if it is a cockeyed-optimist EPA range. (Actually, it showed 409 miles of the EPA's 410 when it stopped charging, so I guess seven months of nothing but high speed charging has not taken much of a toll on the system.) Thanks again!

 

[Steveinarizona]

but I vaguely recall reading that an occasional 100% charge can be good, in that it helps re-calibrate the battery management system for more efficient high-speed charging. (I tried asking about that on the web, and had no luck.)

I vaguely remember that this applies to certain types of batteries (LIPO?) but not most.

 

[Buffalo Bob]

I vaguely remember that this applies to certain types of batteries (LIPO?) but not most.

Yes. See @Adnillien's post a few lines up. This feature does not apply to Lucid's batteries.

 

[Buffalo Bob]

Just try to avoid letting the car sit at 100% for long periods of time, especially in a hot environment.
Cars have varying battery chemistry and BMS design. It's best to listen to the advice given by Lucid for Lucid cars rather than some other advice given by another manufacturer.

Hey, @DeaneG! I'm trying to better understand the first line above... At what SOC level does leaving the car idle in hot weather become a potential problem? I can see where 100% would be risky, but what about a SOC approaching 100%, but not quite there? After I saw your note, I drove around enough to get the car to 97%, but wondered if even that was too high. While probably poorly stated... I'm guessing the problem you are referencing could only arise when the battery is so maxed out that some action or reaction is 'forced' due to there being nowhere else to go.

Also, what temperature would you consider 'hot'? We are hitting around 95 degrees in Seattle today, which would have me running the heater if I were still in Phoenix!

 

[DeaneG]

Hey, @DeaneG! I'm trying to better understand the first line above... At what SOC level does leaving the car idle in hot weather become a potential problem? I can see where 100% would be risky, but what about a SOC approaching 100%, but not quite there? After I saw your note, I drove around enough to get the car to 97%, but wondered if even that was too high. While probably poorly stated... I'm guessing the problem you are referencing could only arise when the battery is so maxed out that some action or reaction is 'forced' due to there being nowhere else to go.

Also, what temperature would you consider 'hot'? We are hitting around 95 degrees in Seattle today, which would have me running the heater if I were still in Phoenix!

"Calendar" battery degradation (unrelated to charging cycle count degradation) is not sudden thing at a particular state of charge or temperature. It's just that at a higher the state of charge, particularly at higher temperatures, degradation will occur faster that it would at 50% state of charge in a cool climate.

There's no need to be super-concerned. If you want to minimize future range loss in your Air, just don't make a habit of charging to 100% every day and letting it sit near there. This is true of all products with NMC battery chemistry - most EVs, laptops, phones, older home energy storage batteries. It's why your phone or laptop runs down quickly after a few years' use.

Other products using the cheaper and less energy-dense LFP chemistry are OK to sit at 100% charge all the time. These include the standard-range Tesla Model 3, and newer home energy storage products like Powerwall 3 and Enphase 5P batteries.

 

[Buffalo Bob]

"Calendar" battery degradation (unrelated to charging cycle count degradation) is not sudden thing at a particular state of charge or temperature. It's just that at a higher the state of charge, particularly at higher temperatures, degradation will occur faster that it would at 50% state of charge in a cool climate.

There's no need to be super-concerned. If you want to minimize future range loss in your Air, just don't make a habit of charging to 100% every day and letting it sit near there. This is true of all products with NMC battery chemistry - most EVs, laptops, phones, older home energy storage batteries. It's why your phone or laptop runs down quickly after a few years' use.

Other products using the cheaper and less energy-dense LFP chemistry are OK to sit at 100% charge all the time. These include the standard-range Tesla Model 3, and newer home energy storage products like Powerwall 3 and Enphase 5P batteries.

Thanks, @DeaneG! I see now. I misunderstood...thinking that letting a battery sit at 100% under certain conditions could trigger an 'event', as opposed to the degrading effect of imposing more stress than necessary over time. Much appreciated!