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Discussion Starter · #1 ·
I put my Mk8 GTE on charge today. Happened to be walking past a couple of hours later to hear the loud humming of the air conditioning working. Why would car decide to randomly turn on the air conditioning whilst charging? Such a waste of electricity!
 

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Cooling the charger, possibly? Was it hot where you are today? Here it was around 24°C, probably enough to kick in cooling for the charging system on my old Tesla, not sure how other EVs cool their chargers when it gets a bit warm. Worth remembering that the charger is in the car, and handles a fair bit of power.
 

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Discussion Starter · #3 ·
Interesting point. Didn’t realise the air conditioning cooled the charger as well as the inside of the car. Checking on We Connect on my iPhone whilst air conditioning was working (when it shouldn’t have been) it showed it was on at 16.5C. The car was in a garage with outside temperature in the low twenties.
 

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The air conditioning system can be used to chill the battery.
I have noticed this at very high outside temperature (>30C, high for the UK)

From the GTE service manual, if the battery exceeds 43C, the active cooling will be engaged.
In 25C weather I had the battery up to 39C after charging (This will run Stage 1 cooling which only uses the radiator and pumps)

It will use more electricity, but the battery will be able to charge faster as a result. If you turn the charge current way down in the infotainment, the pack won't heat up enough to necessitate charging.
 

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Puma GTE > Suzuki Jimny > BMW Z4 > Cupra Leon ST
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Ho
The air conditioning system can be used to chill the battery.
I have noticed this at very high outside temperature (>30C, high for the UK)

From the GTE service manual, if the battery exceeds 43C, the active cooling will be engaged.
In 25C weather I had the battery up to 39C after charging (This will run Stage 1 cooling which only uses the radiator and pumps)

It will use more electricity, but the battery will be able to charge faster as a result. If you turn the charge current way down in the infotainment, the pack won't heat up enough to necessitate charging.
How do you monitor your battery temperature?
 

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I put my Mk8 GTE on charge today. Happened to be walking past a couple of hours later to hear the loud humming of the air conditioning working. Why would car decide to randomly turn on the air conditioning whilst charging? Such a waste of electricity!
Did you have a departure time set by mistake?
 

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Discussion Starter · #8 ·
Fed up with hearing the air conditioning working whilst charging. Booked it into my VW dealer who said it shouldn’t be doing it.
It doesn’t operate the whole time while charging.
How long?
Haven’t a clue!
Unlike charging a Tesla on a Supercharger I can’t see it’s necessary to ‘condition’ the battery when connected to a humble little 13amp granny charger. Waste of electric nevertheless.
I hope in sorting this issue they don’t bugger up something else which is currently working.
Call me a cynic.
”Cynic”.
 

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The firmware on these cars is definitely a bit sub-optimal in terms of power consumption.

For instance whenever the ignition is on, all of the pumps are running, regardless of whether you are moving or not. So the car hummms very slightly when on. Not a big deal but those pumps use 150-200W, so if you just want to sit there with the lights on, you have to spend all that extra power.

But the air con/cooling system for the battery is normal. The GTE's battery is 7.6kWh net capacity. A Tesla might have 10x that capacity and charge up at 7.2kW, and the cooling system will still run. This preserves the life of the battery cells and, more importantly, it ensures all of the cells are at the same temperature. One 'hot' cell could degrade faster than other cells, which in turn can cause the pack to prematurely degrade.
 

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Discussion Starter · #10 · (Edited)
Thanks for that.

Why the hell didn’t my dealer explain this to me. I guess if take it to have this issue ‘repaired‘ they will probably f**k it up. Perhaps I should cancel my appointment.

Next time I fully charge the car I should take note how many units of electricity I use. Back in the winter it was about 10 or 11 but perhaps this time of year it will presumably be more due to the air con working.

Can you direct me to a site/text that explains all of this so that I can forward to them and point out what a load of planks they are?

PS
Just found this on the internet -

Stay plugged in when possible
Many EVs have thermal management systems that moderate battery temperature when the car is plugged in. Staying plugged in when possible, like at home or work, will help these systems keep your battery cool.

OK the GTE is not a EV but I guess the same applies.
 

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These comments are based on the GTE service manual and my technical analysis with VCDS and observations from my own car.

If you want a copy of the SM, send me a PM and I'll drop you a link.
 
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