Battery management issues VW New California T7

[Lebuha]

Today we finally got a complete status on the car. It only took 6 weeks. What happened is: The 12V battery and the camping battery have been running low and at one point the high-voltage battery / hybrid battery has started to charge these two batteries. But it has sent 200 (two hundred) amps and has blown two fuse boxes. So these two fuse boxes need to be replaced along with some connectors. They have been ordered but it is not known when they will arrive.
As I understand it, we are dealing with two different faults. One is that the 12V battery and the camping battery are discharging too quickly, the other is that the high-voltage battery is sending out too much energy to charge the 12V battery and the camping battery.
So now we are still waiting for the car to be ready.

 

[burton61]

Today we finally got a complete status on the car. It only took 6 weeks. What happened is: The 12V battery and the camping battery have been running low and at one point the high-voltage battery / hybrid battery has started to charge these two batteries. But it has sent 200 (two hundred) amps and has blown two fuse boxes. So these two fuse boxes need to be replaced along with some connectors. They have been ordered but it is not known when they will arrive.
As I understand it, we are dealing with two different faults. One is that the 12V battery and the camping battery are discharging too quickly, the other is that the high-voltage battery is sending out too much energy to charge the 12V battery and the camping battery.
So now we are still waiting for the car to be ready.

I will need to look back in case I missed something but I was under the impression that the high voltage battery was not connected/ not charging the leisure batteries or starter battery. If it was that would mean you could effectively use your high voltage battery for camping by allowing it to charge your leisure batteries. I understood VW specifically did not allow that configuration and the high voltage battery was only used for stationary/ camping aircon and heating (30 min durations).

Or are they reporting to you that there is a fault that the high voltage battery is charging the other batteries and also with high current? mmm?

 

[sticky1]

Today we finally got a complete status on the car. It only took 6 weeks. What happened is: The 12V battery and the camping battery have been running low and at one point the high-voltage battery / hybrid battery has started to charge these two batteries. But it has sent 200 (two hundred) amps and has blown two fuse boxes. So these two fuse boxes need to be replaced along with some connectors. They have been ordered but it is not known when they will arrive.
As I understand it, we are dealing with two different faults. One is that the 12V battery and the camping battery are discharging too quickly, the other is that the high-voltage battery is sending out too much energy to charge the 12V battery and the camping battery.
So now we are still waiting for the car to be ready.

Interesting set of faults.
I think everyone is seeing the starter battery drain quickly, some more than others.
It looks like you are also saying the leisure battery is also draining - did they know what is drawing the load.
I can only find the wiring that seems to come from the alternator. As far as I can tell everything in the back of the van draws from the leisure batteries. I need to double check the lighting in the rear.
It would make perfect sense to use the EV battery to charge the leisure battery but there will need to be some clever electronics to cope with the different chemistries and capacities.

 

[Californication69]

Today we finally got a complete status on the car. It only took 6 weeks. What happened is: The 12V battery and the camping battery have been running low and at one point the high-voltage battery / hybrid battery has started to charge these two batteries. But it has sent 200 (two hundred) amps and has blown two fuse boxes. So these two fuse boxes need to be replaced along with some connectors. They have been ordered but it is not known when they will arrive.
As I understand it, we are dealing with two different faults. One is that the 12V battery and the camping battery are discharging too quickly, the other is that the high-voltage battery is sending out too much energy to charge the 12V battery and the camping battery.
So now we are still waiting for the car to be ready.

Tak from Copenhagen this Evening !
This is really good information.
Would be nice to have some definitive answers from VW as to how the battery (EV, Starter & Lesuire) interact with each other.
My understanding is that VW don’t have a clue how it works to be honest.
Looks like we could have a clearer picture emerging from the Dansker, which wouldn’t surprise me tbh.
They know their stuff.
Their knowledge with electrical testing equipment ‘tis legendary, way faster than VW can find the blueprints

 

[sticky1]

What I don’t understand is that the hybrid multivan has been around for some time so surely the only addition is the leisure batteries in the back.

 

[vbk1975]

Interesting set of faults.
I think everyone is seeing the starter battery drain quickly, some more than others.
It looks like you are also saying the leisure battery is also draining - did they know what is drawing the load.
I can only find the wiring that seems to come from the alternator. As far as I can tell everything in the back of the van draws from the leisure batteries. I need to double check the lighting in the rear.
It would make perfect sense to use the EV battery to charge the leisure battery but there will need to be some clever electronics to cope with the different chemistries and capacities.

BEVs / PHEVs don't have a traditional 12v alternator. On the PHEV the generator is HV and the energy is used to power the rear electric motor, aircon/heater, DCDC and the HV battery (to varying degrees).

The DCDC converts HV to LV (~12v-14V) power for all the traditional LV parts of the vehicle, (Basically think of the DCDC as an alternator) including the charging of the LV batteries. In addition some vehicles have the ability to top up the 12v starter {although not really a starter battery} via the DCDC using the HV pack even if the vehicle is not in use.

I do wonder if some of the issues being seen is as a result of the extra camper elements being added into the base vehicle and throwing up issues.

On the T5 & T6 California the Camper electrical systems were very much an add on, limited interaction with the base vehicle. The Camper control panel is not connected to the base networks etc, hence only diagnostics being via the display etc. The spilt battery was a base van option and again basic. So whilst it had a few niggles, you tended to have the generic van issues that everyone suffered from or camper specific issues but limited interaction.

On T6.1, they integrated most of the camper control elements into the base van and that threw up new issues.

I am assuming that the 2nd battery is only used on the camper variant of the PHEV and that between the camper elements and the 2nd battery it has uncovered new conditions.

In terms of the specific issue that @Lebuha has had, the DCDC doesn't push out more energy that required, it can supply probably ~200-260 amps, but the fuses can only have blown if the current is being pulled through them by the devices on the other side. That sort of damage sounds like a dead short. If it was my car, i would want a pile of photos of the damage, specifically the harness, records of exactly what is being replaced and how. 200Amp fuses (this is continuous rating) , so they will need in excess of 400Amps to blow. Fuses of that size are only used on very significant power feeds and it is extremely rare (outside of a crash) to have them blow.