Battery Health - How much degradation is normal?

[larrycpa]

My 2024 Pure, 25 months 24k. Lucid Tracker shows it at 89%. Testmycode shows 93%. The former would lead me to turn the car I at lease end. The latter would lean toward keeping it if the economics are ok.

 

[borski]

Good to know, thanks. It's somewhat reassuring... but still baffling since my car should be the poster-child for battery health given how its driven, stored, and charged. I feel like when I read about other people's battery health, it's 96% or 97% on a 3-year old car.

The first year is always, by far, the worst for degradation. Older Teslas used to lose almost 10% in the first year.

It slows down to a trickle after that.

 

[borski]

What about BMS calc and sway? If you never go down to single digits or let it sit on AC L2 or L1 for a couple hours at 100% to make sure it’s really 100%?

This was my second thought. You can rebalance the cells by letting it sit at 100% for 72 hours, and then I’d be curious what the value was at 80%.

 

[borski]

My 2024 Pure, 25 months 24k. Lucid Tracker shows it at 89%. Testmycode shows 93%. The former would lead me to turn the car I at lease end. The latter would lean toward keeping it if the economics are ok.

Testmycode is returning the value from the API.

If you rebalance (keep your car at 100% for 72 hours), I’d be curious to know if LT tracks it properly then

I don’t know how @HC_79 is calculating it.

 

[jbawden]

Is it plausible that what we think are best practice for battery health is not a fully vetted conclusion?

 

[borski]

Is it plausible that what we think are best practice for battery health is not a fully vetted conclusion?

Very. The general concepts are correct, as outlined previously. How they specifically affect these cells / packs? No idea.

 

[HC_79]

My 2024 Pure, 25 months 24k. Lucid Tracker shows it at 89%. Testmycode shows 93%. The former would lead me to turn the car I at lease end. The latter would lean toward keeping it if the economics are ok.

Use the "Ask for Help" agent on LucidTracker and tell it you need open a ticket. I can then look at your account and see if something is off.

 

[ExCivilian]

If you rebalance (keep your car at 100% for 72 hours)

Is it documented that we need to maintain the vehicle at 100% for 72 hours to rebalance the cells? I charge all my EVs up to 100% overnight first of each month but I don't leave it there for 3 days.

 

[borski]

Is it documented that we need to maintain the vehicle at 100% for 72 hours to rebalance the cells? I charge all my EVs up to 100% overnight first of each month but I don't leave it there for 3 days.

That is what service told me. Technically it can be anything above 80% for 3 days, but you just need to not have it drop below 80%.

But it cannot be driven or unlocked in that time or the cycle starts over.

(Yes, I also think its annoying, which is why service is usually the one to do it, albeit it’s just sitting there for 3 days lol)

 

[Aka-none]

That is what service told me. Technically it can be anything above 80% for 3 days, but you just need to not have it drop below 80%.

But it cannot be driven or unlocked in that time or the cycle starts over.

(Yes, I also think its annoying, which is why service is usually the one to do it, albeit it’s just sitting there for 3 days lol)

So that’s your understanding of what triggers the BMS to rebalance the cells? Interesting it could occur at such a low state of charge.
This is oft discussed in the cruisers forum (a lot of sailboats)
My understanding is the state of charge is difficult to read as the discharge curve is so darned flat and the bms needs sufficient overhead to feed cells by manipulating the charge voltage presented to them.

 

[borski]

So that’s your understanding of what triggers the BMS to rebalance the cells? Interesting it could occur at such a low state of charge.
This is oft discussed in the cruisers forum (a lot of sailboats)
My understanding is the state of charge is difficult to read as the discharge curve is so darned flat and the bms needs sufficient overhead to feed cells by manipulating the charge voltage presented to them.

Yeah, that’s my understanding. I am not 100% certain tho

 

[petergottlieb]

Use the "Ask for Help" agent on LucidTracker and tell it you need open a ticket. I can then look at your account and see if something is off.

This is about Lucid tracker assuming a 88 KwH battery for a Pure while Lucid's internal API data assumes 84 KwH. I understand it's a bit of a convoluted thing, but all and all, I would love Lucid Tracker to default to Lucid's API on this...

 

[illopp00]

This is about Lucid tracker assuming a 88 KwH battery for a Pure while Lucid's internal API data assumes 84 KwH. I understand it's a bit of a convoluted thing, but all and all, I would love Lucid Tracker to default to Lucid's API on this...

I think 84KWH is only for 2025+ RWD Air Pure, the older ones are 88KWH.

 

[petergottlieb]

I think 84KWH is only for 2025+ RWD Air Pure, the older ones are 88KWH.

Yeah, this is the convoluted part... It's not clear the battery itself changed... it may still be 88 gross, but it does seem that the API on 2025 and new Pures at least, does it's figuring from the net 84...

 

[imperium2000]

I think people are overthinking it about rebalancing cells. From my understand, just let the BMS do its job.

For NMC batteries, it is generally not good to let the batteries sit at a high state of charge and it is not necessary to charge it to 100% to recalibrate the BMS. NMC has a very linear voltage curve so its not necessary. The BMS will rebalance the cells when it sits a higher state of charge or when you're charging it. It is ok to charge it to 100% occasionally but most recommendations is to not let it sit at such a high charge state for too long.

For LFP batteries, it is recommended to charge it to 100% once every few months to recalibrate the BMS since the voltage curve is very flat and the system can get out of whack with time.