Vehicle Battery Issue - GC600

[Mistabushe]

Good Morning,
Hope everyone is having a fantastic weekend in their vans...

Hoping for some advice, so I can understand what's going on with my GC600.
We have a 2025 GC600, from new Sep '25.

Went to use on Saturday morning, drove down to Dorset (2 hours), on arrival a warning came up that the main battery is low.
Checked the Control Panel, and the readout confirms it.
Drove home, same message and Control Panel the same, so no charge from the engine.
Vehicle starts fine, atm.

We have had the van plugged into the leisure battery, while not being used, so always topped up to 100%.
Last used the van on a trip to Devon 3 weeks ago, no issues as far as I know.

Yesterday I purchased a Ctek charger and connected it up last night, directly to the engine battery.
Still charging this morning, but no change to Control Panel readout for engine battery.
But overnight the leisure battery is now drained to 10%.???

Not entirely sure what is going on, or what I'm doing wrong? Any advise would be greatly appreciated.

Have I got the charger connected correctly, as in directly to the battery? Is it charging? No faults detected off Ctek.
Do I need to wait a lot longer for it to take charge?
Is the battery now damaged?
Is the alternator faulty, as doesn't appear to be charging on driving? Or is it because its too depleted?

Picture attached from when we arrived in Dorset.

Sorry for all the questions.

Many thanks,

Kev

 

[GordonH]

I have a pre-25 model so can't run any checks to confirm but it looks to me the warning is related to your starter battery (the one under the passenger seat) as that provides power to the infotainment. Charging the leisure battery (the one under the bonnet) won't directly impact that (until you start the van when charge relay usually closes). There was an early issue with MY25 van where the hookup charger did not charge both batteries, only the leisure battery, it was the subject of a VW TPI, make sure that has been addressed.

 

[markab]

Good Morning,
Hope everyone is having a fantastic weekend in their vans...

Hoping for some advice, so I can understand what's going on with my GC600.
We have a 2025 GC600, from new Sep '25.

Went to use on Saturday morning, drove down to Dorset (2 hours), on arrival a warning came up that the main battery is low.
Checked the Control Panel, and the readout confirms it.
Drove home, same message and Control Panel the same, so no charge from the engine.
Vehicle starts fine, atm.

We have had the van plugged into the leisure battery, while not being used, so always topped up to 100%.
Last used the van on a trip to Devon 3 weeks ago, no issues as far as I know.

Yesterday I purchased a Ctek charger and connected it up last night, directly to the engine battery.
Still charging this morning, but no change to Control Panel readout for engine battery.
But overnight the leisure battery is now drained to 10%.???

Not entirely sure what is going on, or what I'm doing wrong? Any advise would be greatly appreciated.

Have I got the charger connected correctly, as in directly to the battery? Is it charging? No faults detected off Ctek.
Do I need to wait a lot longer for it to take charge?
Is the battery now damaged?
Is the alternator faulty, as doesn't appear to be charging on driving? Or is it because its too depleted?

Picture attached from when we arrived in Dorset.

Sorry for all the questions.

Many thanks,

Kev

View attachment 148106

Hi Kev,

I have some experience with this issue on my September 25 GC, the issue has occurred twice once in month 2 and once last week.

Background, when we are away we are on hookup 99% of the time, when the van is not being used it is on hookup 100% to keep everything topped up.

So on both occasions for me the first sign of issue was the the rear step would not operate, the bluetooth on the rear control panel would disable right after enabling and the fridge would do a similar thing where it would disable after enabling but then mysteriously enable again later.

The engine would start fine but when ever turning off the ignition the infotainment would report the vehicle battery was low. On the rear control panel during the first instance of the issue it showed the vehicle battery low and no matter how long a run the error message continued to display when turning off the vehicle.

The second instance last week, the rear control panel showed the battery completely dead with a line through it. Again long runs did nothing to fix the problem.

The first instance seemed to fix it self after a week on hookup when the vehicle battery charge state seemed to sync over time.

The second occurred when we were away and as it was causing issues with the step, fridge and other bits I did a bit more digging.

Firstly I tested both batteries for voltage and resistance and confirmed they were both drawing current from the alternator when the engine was running, all was fine, both batteries were fully charged and healthy but the error was still there.

Next I switched off the rear battery isolator for 10 minutes in an attempt to reset the rear control panel... this did nothing, the control panel still showed zero vehicle battery.

Next I disconnected the negative terminal on the vehicle battery in the passengers footwell for 5 minutes. This did the trick and seemed to reset the vehicle battery management. The infotainment no longer reported low vehicle battery and the rear panel showed the charge state on both batteries again immediately.

The remainder of our weeks travels were fine both on and off hookup.

So it seems there is no problem with the batteries or charging for both engine or hookup charge. The problem seems to be that the vehicle ECU or BMS seems to get confused and needs a restart, when you do this I assume the camping side picks up the correct data from the vehicle side again.

The annoying part is that the camping side should not be restricted by the vehicle battery state otherwise what is the point it seems bad instrumentation causes other functions to not want to work.

So my suggestion to you is disconnect the vehicle battery to reset the ECU and it should be fine. to do this you need to remove the passenger floor mats, then the tool box lid (2 twist knobs). Then 3 screws that hold trim on the top of the foot step, lift off the floor panel then you will see another black floor panel, lift this then you see the vehicle battery.

Note after you do this you will likely get some ABS and sensor warnings associated with the system being reset. Either start the engine and drive a short distance or start the engine then turn the steering full lock one way hold then full lock the other then hold. Stop and start the ignition and all the issues will be reset in the vehicle status page.

I did also read about the hookup charging software issue however my van is beyond the trouble serial number range and the battery is charging fine, this seems to be another issue, I will report to VW on first service.

The Electrical design on this van is not very smart.

 

[markab]

Note I did try unplugging the vehicle batter sense cable, connector near the battery terminals but I found disconnecting and reconnecting this made no difference and the full battery disconnect was needed.

 

[Mistabushe]

Thank you both for taking the time to respond. Really helpful. - I will have a little play based on your info. & see how I get on. Enjoy the rest of your weekend.