Hymer MLT 2018 Battery Problem

[DJT]

After having driven 230 miles in stop start traffic on the M6 with the fridge running auto on 12volt setting.
Stopped for fuel for no more than 10 minutes and on trying to start the van the starter battery was flat.
Started first time with Noco jump start and was fine after being on hook up on site
The van was on hook up at home before we set off.
The starter battery on the van would be approx 3 1/2 years old.
Should the 12v power for the fridge not be drawn from the leisure battery?
Any clues/help would be appreciated.
Thanks in advance.
DJT

 

[Guigsy]

If the fridge is 3-way (so it can run on gas), then it'll be wired so it pulls from your cab battery, but only while the engine is running. It shouldn't have drained the cab battery as the alternator should have provided enough juice.

If the fridge is 2-way (a compressor fridge) then it will pull from your hab battery. But when the engine is running, it'll pull power from the cab electrics as it assumes there's more than enough from alternator.

Maybe your alternator is not working? When you start the engine, does the voltage increase from ~12.5v to ~14v?

 

[DJT]

Thanks Guigsy it’s a start i will keep you posted
DJT
P.S.
(It is a 3- way fridge)