Battery cells reset/rebalancing after erratic SoC readings

[craz8]

So should run this discharge / charge once again

Nope, just charge from 85 to 100 again and wait a second time. It will eventually understand where 100% should be

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[ChrisFromUK]

So I charged to 100% last night, range was 212 miles
Charger showed 77kw energy ( 5% to 100%)

This morning pcm was showing 85% and 284 mile range

So should run this discharge / charge once again ?

You've added 77KW which is about 81% SoC. 81%+5% is pretty close to the 85% SoC your car is showing so this is probably accurate now.

I think all you need do is charge again to 100% and see if it stays there. If it drops (it likely won't) then charge again to 100%.

 

[minsc]

Thanks guys

 

[Wivenhoe]

I had similar but not as extreme issues with my March 25 S. My dealer had the car for 5 days and it came back as it was when I originally collected it. They told me that they consulted Germany and installed 5 or 6 smallish updates - one of which was battery management. They charged the car (on 11kv) and ran it for only about 100 miles then topped it up to 100%.

 

[Cogs79]

Hi, I got back from travel on Monday, and the car lost 17% charge in 17 days (not plugged in). I charged to 80%, and the next day when I finally had to drive it, it showed 83% on the dash (80% in the app). I never charged to 100%, or did the discharge procedure yet. I won't take the car in to the dealer but I documented everything and will give them all the details next time I need to swap tires (in a few months). Hopefully the little software updates everyone is getting after 28.13 will help.

 

[oxum]

Mine started to show erroneous SoC as well after the 28.13 update at the dealer. This happened on a smaller scale before the update (I would charge to 85% and the car would show 79 in the morning).

But now it is literally half my range that is gone. So I am following you guys advice from this thread.

First time after a night spent unplugged sitting at 5% the battery rebalanced to 18%. Good surprise so far. I then drove it down to 3% and let it sit overnight again... the next day it was still at 3%.

I figured it was not gonna rebalance at that SoC anymore so I plugged it in. Charged to '100%' today while in reality only putting in 43kW of energy in at the wall..

I am now waiting to see if SoC drop overnight again to keep adding juice. It's like half of my battery capacity is missing. Truly shit.

 

[Cogs79]

Mine started to show erroneous SoC as well after the 28.13 update at the dealer. This happened on a smaller scale before the update (I would charge to 85% and the car would show 79 in the morning).

But now it is literally half my range that is gone. So I am following you guys advice from this thread.

First time after a night spent unplugged sitting at 5% the battery rebalanced to 18%. Good surprise so far. I then drove it down to 3% and let it sit overnight again... the next day it was still at 3%.

I figured it was not gonna rebalance at that SoC anymore so I plugged it in. Charged to '100%' today while in reality only putting in 43kW of energy in at the wall..

I am now waiting to see if SoC drop overnight again to keep adding juice. It's like half of my battery capacity is missing. Truly shit.

Ok in my case, when I got back on Monday (after the battery discharged ~17% in 17 days), I charged it back to 80%, and my charger shows 16.5 kWh added so mine was not off by much (it did jump to 83% in the morning) There's a few issues going on, from high battery discharge rates when parked, to loss of accuracy with the state of charge. I might not wait until I swap my tires to have them look into this. Thankfully we get an 8 year warranty in Canada (and US?) on the EV components and battery.

Hopefully this recalibration process fixes your battery capacity!

 

[oxum]

So, good news follow up: after sitting for a bit at 100%, I entered the car the battery SoC melted on the dash down to 85% soc, with the range already increasing in its estimate.

It took two more rounds of this with 16kW and 2.5kW respectively to reach the solid 100% and correct estimates for range. I am glad it's back in order, and also glad i didn't have to waste my time explaining this to the dealer in order to get some solution.

You guys rock, forums like this one are truly lifesavers at times.

 

[byebye]

Is Porsche Macan the only EV on earth with a BMS that doesn't manage the battery?

Shame on you Porsche for not being able to fix immediately this sort of issue, and keeping your customers in the dark.

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