Battery loses SoC while parked, strange charging behavior

[dimaa_6abc]

This started abruptly, but quite early in car's life - at around 6K km. Before that everything was perfect. I have a charging target of 80%, and smart wall charger which starts the charging on schedule, usually at 11PM or 12AM, so we plug it in and leave it, charging will start at night and will be completed in 4-5-6 hours depending on the initial level. Last few charges I found that it cannot reach that 80% level. When charging from 20+, it stuck at 76%, from 30+ at 78%. What is interesting - charger shows two drops in amperage, one to about 1/3 of full power for about 20 minutes, then to 2.3A (instead of 50) for exactly 3 hours. Car shows 0 kW at that time, meaning 0.5 kW goes somewhere but not into the battery. No A/C settings have been changed. Once I opened the car while in that state, it woke up and started charging to 80% at full power.

Also, it seems it cannot estimate state of charge precisely. Once right before the long trip it was left to charge from 75% to 100%, got 22 kWh and showed low 90s instead of 97%. Then it did not drop after driving 20 or 30 km, and started dropping by very slow rate (not usual 1% per 5 km it is supposed to do). Closer to 40% it started dropping rapidly, like 1-2-3 km per 1%. When plugged in, 30-70% consumed 30 kWh, not 40. And now I'm in strange city and SoC drops 1-2% each day while parked in underground garage where it is not too hot. SoC is well below 80%, low chance of cooling the battery. I already charged it to 100% using slow charger with the hope it will recalibrate itself, it reached 100% and did not lose it overnight which is already a good sign (it was a public charger so I unplugged it late in the evening), but SoC is still lost somewhere. I will come home and call the dealer, but if this is a rare scenario, I won't hope for a quick fix.

Communication module is not installed in my country, so there is no chance it will update the software or be awakened by the app.

Sponsored

 

[pm4s]

Does it lose charge when it is unplugged as well?
Asking because macan charges 12v battery when plugged in.

 

[dimaa_6abc]

Does it lose charge when it is unplugged as well?
Asking because macan charges 12v battery when plugged in.

Sorry, I put more emphasis on inability to reach target SoC, while I'm more concerned with losing charge while parked. It is unplugged now, while it loses charge, around 1% per day. So far, I have found 2 similar cases on forums, people are not too much concerned, nobody contacted the dealer yet. I see this situation as disastrous, car is clearly broken when it behaves this way. Especially knowing that 2 months ago it did not lose a single % in two weeks.

 

[TurboSpain]

Last few charges I found that it cannot reach that 80% level.

I saw the charging graph you posted on rennlist. The temperature caught my attention; it reached 47-48 degrees.

I'm not sure, but could it be that it stopped charging because it reached too high a temperature?

Regarding discharging while parked, if it's very hot in your area, the battery cooling system may activate, and that could consume quite a bit of power. I'm assuming you don't leave the car in direct sunlight for long periods of time.

 

[dimaa_6abc]

I saw the charging graph you posted on rennlist. The temperature caught my attention; it reached 47-48 degrees. I'm not sure, but could it be that it stopped charging because it reached too high a temperature?

That was the temperature of the wall charger, not the car battery. Graph is from the cloud service of the smart wall box manufacturer. Just got an idea of talking to their support to confirm that car indeed asks for those 2-3A of current, maybe they will setup debugging session when I'm back and ready to plug their wall box into the car.

Regarding discharging while parked, if it's very hot in your area, the battery cooling system may activate, and that could consume quite a bit of power. I'm assuming you don't leave the car in direct sunlight for long periods of time.

Car is parked underground in Berlin. It was very hot here (+35C for 3 days), but underground temperature hardly reaches 25C. So far, I count 2 people experiencing this - one in rennlist (where I replied to the topic with such issue) and one here, where car lost 10% in 10 days. My case combines inability to reach target SoC when plugged in and using delayed charging with losing SoC while unplugged, both problem started at around the same time, before that everything was fine. I believe they have the same cause, and it will not go away by itself, car definitely needs attention. Trying to gather experience of others, maybe it will help to solve my case.

 

[TurboSpain]

Ok. Did you try another EVSE? The temperature it reached is almost at the limit of what mine can handle (50 degrees). In fact, it never exceeded 40 degrees, even though it's a 32A charger.

 

[dimaa_6abc]

Ok. Did you try another EVSE? The temperature it reached is almost at the limit of what mine can handle (50 degrees). In fact, it never exceeded 40 degrees, even though it's a 32A charger.

Yes, I did, we have two EVs (Macan is actually a daily driver for my wife, but we took it for the long trip to Berlin) and in case they must be charged the same night - two EVSEs. Same picture, same current chart. Both EVSEs are perfectly fine when charging BMW iX. Problem is not with the EVSE.

Just looked at temperature values for another (portable) EVSE and it is above 50, which does not prevent it from charging BMW without any issue.

 

[pm4s]

Mine regularly sees 55 degC when DC charging in the sun, even 30min later after charging if I park and leave the car I can still hear from the top floor the fans going strong, so no issues here. The car will cool the battery down.

 

[M324]

I've got my car parked in a garage where it usually get's maximum 25 degrees and I am mostly charging during the night. I also recognized what you described for the last two times charging. Even though I've set it to 80%, the car suddenly just charges till 78%. I will keep an eye on it.

 

[dimaa_6abc]

I've got my car parked in a garage where it usually get's maximum 25 degrees and I am mostly charging during the night. I also recognized what you described for the last two times charging. Even though I've set it to 80%, the car suddenly just charges till 78%. I will keep an eye on it.

So the problem is not so rare. Does it lose SoC when it sits locked and unplugged for few days? I feel this should be related somehow.

 

[M324]

No, it's rather losing SoC when plugged in and charging. Not when it's unplugged and not charging.

 

[dimaa_6abc]

No, it's rather losing SoC when plugged in and charging. Not when it's unplugged and not charging.

So, ours does both - loses SoC when plugged in, and loses it when not plugged in. How nice... Some people admit the former, and some the latter, I seem to be the only one with both. Owner in neighbor thread who has SoC loss when not plugged in brought the car in for inspection, hope we will see some details soon.

 

[dimaa_6abc]

No, it's rather losing SoC when plugged in and charging. Not when it's unplugged and not charging.

BTW do you use delayed charging, or charging starts immediately?

 

[M324]

Immediately

 

[scharnhorst310]

This is anecdotal but now that I think about it, i've seen this happen as well. Usually have the charge target set to 60 or 65, and seemingly at random the car will be at 58 or 63% the next day. Plugged in the whole time.

My think is that the battery management computer has recalibrated after charging but has already sent the stop charge command. I've got a camera in the garage and even when the garage is very hot, I don't hear the car AC/Fans whatever spin up.

Sponsored