Battery only charging to 88%???

[devmach-e]

If my target charge is 85%, and the car charges to 85% and stops, but then later the car thinks the charge level has dropped to 84 or 83 or 82%, why is it not topping up since it is still plugged in?



I do, and I understand that measuring exact charge level is tricky. That's not the point of this thread. Something has changed that now results in a 3-4% drop in indicated charge level after a charge. My garage was 44 degrees all winter, and charging to 85% left me with 85% or 86% on start up. Now my garage is 54 degrees, and a charge to 85% is now 82% on start up. I have had my car since Jul 2021, and up until the last month, it has behaved exactly the same on every not-100% charge, no matter what the temperature. Temp affected the estimated range, and maybe would cause a 1% drop when I left it outside for 8+hours, but never caused a drop in charge while it was still plugged in.

Either something has changed in the software (which I've already admitted is the most likely cause), or several of our batteries have all had a drastic change in the last month. Those of us experiencing this just want some confirmation that this is a software thing and not an indication that something bad has happened to our batteries.

The car's notion of a specific SOC drifts with time. No BMS is perfect at tracking coulombs in and out of the battery. Going by voltage level isn't accurate, either, because there's a fairly flat curve (worse so for the LFP chemistry). And the notion of the stored kWh available is highly dependent upon temperature of the cells.

If you are really concerned, do a charge to 100%. Or do the re-calibration process that @Mach-Lee has written up. It will reset things, as I can personally attest to. But it will eventually drift again.

Unfortunately I don't know why it will charge to 88% instead of 90%. I just know that this phenomenon existed in my Bolt EV, and just like with the Mach-E, charging to 100% periodically would reset things back.

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[axelheimer24]

Did you check that there is enough plutonium for the flux capacitor? Classic issue for not getting the expected outcome at 88.

 

[ChasingCoral]

Either something has changed in the software (which I've already admitted is the most likely cause), or several of our batteries have all had a drastic change in the last month. Those of us experiencing this just want some confirmation that this is a software thing and not an indication that something bad has happened to our batteries.

I think you are right. I had a recent charge session that dropped much like the OP's. This is more than I usually have seen in my car. We did receive some battery charging updates recently that may have introduced this change.

Keep in mind, this may be a long-term change due to the new software or it may be a readjustment that will go away. Only time will tell.

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