Slow level 2 charging and high OBC water temp

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andrew1joe

Active member
Joined
Feb 27, 2019
Messages
25
Hello,

I am wondering if anyone else has problems with slow level 2 charging. I have a 7kW charger which my wife's Chevy Bolt fully utilises every time. However my Kia Soul EV 2018 30kWh model sometimes charges at 6.6kW but other times charges at much lower speeds. Here is an example charging at 4.2kW with 60% SoC:

Screenshot-20190803-161334.png
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As you can see, the battery isn't hot at all and the ambient temperature normal. The only thing is that OBC water temp is at 79 celsius / 172 fahrenheit and I've seen it go even higher. I can hear the fan going at full speed even though Batt Fan Mod is 0 - maybe because the car is turned off? I see a pretty close correlation between high OBC temp and low charge speed which I assume is the car trying to protect itself from frying the OBC unit which it seems to have been common with the first gen Soul.

I am afraid my OBC is doomed to suffer a similar fate... Anyone noticed a similar pattern?
 
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There is something wrong with your coolant system. Yes.

The OBC is liquid cooled. It uses an Electric Water Pump.
The battery fan at the back has no relevance or connection to the motor cooling system at the front.

Here's some testing I did of the EWP last year. :- Electric Water Pump
JejuSoul said:
I had a look at some Torque logs of a recent driving session in a 2018 Soul EV to watch how the EWP worked as the Temp increased.

I watched the Motor Temperature go up to 55C while driving at 90km/h. This was the lead indicator.
The VMCU MCU Temperature followed this but every time this reached 40C the EWP came on and began cooling it.

When the EWP came on the OBC Water Temp began to rise. Obviously because it is on the same coolant loop.
Next to rise is the OBC Heatsink Temp closely followed by the OBC Inside Temp.
The coolant never went above 37C, The Heat Sink got to 35C and the OBC Inside got to 34C.

I have named two new PIDs for the EWP. 'EWP Control Target' and 'EWP Speed'.
The EWP Control Target was zero at first but changed to 51 every time a few seconds before the EWP came on.
The EWP Speed was zero when it was off and 43, 44 , 49 or 51 when it was on.
During driving the OBC is not used, I show this just to show how the coolant loop works.
Here is a screen from Torque showing the temperatures when my car is charging.



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Thanks for confirming this isn't normal behaviour. I am due for my 1 year checkup so I'll bring it to the dealerships attention.

I wonder if this is what happened to others who had OBC coolant leaks...
 
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