Car Finally going for M.O.T. next Wednesday however the latest problem is it's draining the battery over the space of a couple of nights in the garage.
Bought a new battery in February, drained it flat and won't charge. Cheap 45 quid crap of Ebay.
Bought another new battery 85 quid. Drained flat in the few days it took to sort the sump gasket and a few other bits.
My charger won't charge a battery from flat so stuck a battery I had lying about that's never given any problems.
Even this is dropping charge by about 5/6 volts overnight?
Alarm is switched off as it's goosed, heated windscreen disconnected as tabs were broken replacing windscreen rubber.
At a loss as to what can be causing this.
Any pointers appreciated, Thanks.

 

Usual items are
Alarm - definitely disabled/no power?
Immobiliser (would obv be aftermarket on this if you've got one)
Interior light
Boot Light
Stereo/AMP/ICE not swiching off properly (e.g. someones got continuous live to their amp in error..)

Easiest way is to establish the parasitic drain on the battery and then pull one fuse at a time and see what happens. If you see a sudden drop off on amps being pulled, you know thats the circuit to trace.

Bear in mind there will always likely be some kind of parasitic draw, so don't try and get it to dead zero. But if you are genuinely killing a fully charged 12.6V battery overnight then the cause should be easily found

 

Loads of articles out there - first one I found covers the high level basics at a glance
https://www.team-bhp.com/news/idiots...in-modern-cars

Just remember modern cars are very different in the amount they draw etc - they have a billion integrated systems. An RS turbo has some of the simplest and straight forward wiring there is, more so on the interior side.

 

Thanks for that Haz.