SOC drop

[freinando]

I rarely let my car get below 40% SOC. This last week, however, the car sat below 40% SOC a couple of times, and, in both instances I noticed an abrupt SOC loss of about 6% apprx. For instance the car sat for 3 hours parked when at 36%, when I came back it was at 30%. This happened in 2 separate instances as I mentioned.

I never experience SOC drop while parked any other time, it seems to only occur when below 40%. I assume this is some sort of cell rebalancing kicking in, which would mean the battery isn’t healthy? No yellow or red rings yet, but I assume I’m due for one soon and, in the meantime cannot ask Porsche to diagnose anything since no faults have been recorded yet. I’ll plug CT14’s tool tomorrow and MapEV diag /carscanner to see if there’s anything there.

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[whitex]

I’ll plug CT14’s tool tomorrow and MapEV diag /carscanner to see if there’s anything there.

Logical next step.

 

[69Mach390]

I rarely let my car get below 40% SOC. This last week, however, the car sat below 40% SOC a couple of times, and, in both instances I noticed an abrupt SOC loss of about 6% apprx. For instance the car sat for 3 hours parked when at 36%, when I came back it was at 30%. This happened in 2 separate instances as I mentioned.

I never experience SOC drop while parked any other time, it seems to only occur when below 40%. I assume this is some sort of cell rebalancing kicking in, which would mean the battery isn’t healthy? No yellow or red rings yet, but I assume I’m due for one soon and, in the meantime cannot ask Porsche to diagnose anything since no faults have been recorded yet. I’ll plug CT14’s tool tomorrow and MapEV diag /carscanner to see if there’s anything there.

Not necessarily an indicator of anything wrong. Displayed SOC is always an estimate. Could just be the difference between a warm battery after driving and a cold one after sitting.

 

[freinando]

Displayed SOC is always an estimate.

I would think range is an estimate, but the car should be able to reliably state an accurate SOC number. One percent deviation, sure, but 6? Also only occurs at below 40%.

 

[Sace]

My car has always had a tendency to drop in SoC in exactly that range (30-40%). It's only in that range and there is nothing wrong with the battery according to the different tools mentioned here. Pack perfectly balanced.

Suspect it's just a "feature" on the BMS for that particular range.

 

[r553]

Do you possibly have any post shutdown cabin heating/cooling enabled? Is your range after charging reasonably consistent? I lost 60 miles of range in one week and it turned out to have been bad cells in the HV.

 

[Tpup]

Did the pre-climate come on? Even though I have that turned off on my car I occasionally get a notification that pre-climate is complete. I also noticed that my range goes down if I'm parked outside in FL doing errands vs just leaving my garage (have AC) going somewhere, and coming right back to the garage.

 

[SergeyIndy]

My next would simply be to use an OBD/CarScanner to get the readings on the SoH and then 3 cell graphs that would show if any individual cells going bad. If you see outliers, then I would do a rebalance and then redo the SoH and cell graph readings and if you still have outliers, that would indicate that cells are bad and you need to replace them.

I am not sure what value CT14 scan brings, but interested in the process and outcome of that.

Happy to help with step by step on how to do the above.

I do readings every 1k to proactively detect bad cells for that same reason and rebalance every 5k miles.

However, the lateste OTA updates are supposed to monitor the cells and alert the driver with in car message, but it may be tuned to do so when things are already almost dead.

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