Technical New battery goes flat ?

[NEWBIEVANER]

HI I have a 2005 fiat Ducato 2.8 JTD Hymer C class 614 GT motorhome with only 34000 miles on the clock.

The starter battery it came with was a bit unreliable so I changed it for a 12 volt 85 ah brand new battery, worked a charm every time.

I also fitted one of these Chinese 10 inch LCD screened entertainment units in place of the usual radio so I can use the sat nav for getting around, bit fiddly to get it to fit but it works great despite the rubbish instruction manual with it.

Whent out for 5 days camping came home and parked it up, three weeks later I tried to start it the battery is completely flat 2.3 volts , the only thing drawing power from the starter battery with the engine off, as far as I know, is the alarm system a cobra alarm and this radio as when I wired it in it had a permanent live feed so that it can be used without the engine being on.

Could this purely be down to the alarm and radio, or is there another issue with the vehicle, anyone come across this before ??

 

[Communicator]

There have been several threads relating this problem. The general consesus seems to be that 3 weeks to flat battery is not unusual. You 85Ah battery will not help. I would be looking for a least 95Ah with CCA rating of 800A, when replacing the battery on my 2.8jtd.
I would normally suggest that the conversion details are irrelevant in base vehicle problems, but Hymer use Schaudt habitation electrical systems. The Schaudt Electroblock provides a trickle charge for the starter or vehicle battery, but EHU would be required.
As an alternative you could use a Vanbitz Battery Master or similar device. This maintains the starter battery from the habitation battery, and is useful if only the habitation battery is charged from a solar installation.