Tge oem split charge

[K13rmj]

Hi all Recently received a 2019 man tge works van for on site fitting ect
The van came with a sterling power charger wired into the battery under the passenger floor, I believe this is draining the battery as when went out to start it after a few days the battery was flat,
After doing a bit of research iv found out that this van has a main and an aux battery under the bonnet and is linked via a relay behind the engine bay battery (aux), has anyone successfully used this as a leasure battery to the extent where if the aux battery discharges the main battery under the floor will still start the van then charge the aux battery via the oem relay both battery’s are vw agm
Thanks

 

[rod_vw]

I don't know how the van was accessed and perhaps used during those few days but you will find that the TGE/Crafter has a considerable drain on the engine battery just by unlocking it and opening the door. You will find that just with a week of pottering in and out without starting will drain a lot off the engine battery.

The Stirling Power unit should be capable of charging the second battery correctly but I suspect that the battery capacity is rather small for use as a camper leisure battery.