Help again please =)

[kaizokuninja]

So, i have been having this issue as the use of my car has gone down, and i suspect it's my HU.

It used to happen in my mini if 4-5 days went by that i didn't drive the motor and the only relation between my A3 and my mini is the Head unit.

I'm thinking that it might just be an Earth problem as i use the Earthing that is wired into the harness and not an actual body earthing so before i go and buy myself a new HU i wanted to know:

Is this a common problem, and is it caused by a faulty earth?
If not is there a reason that a HU would drain the battery when the ignition is off?
is there anyway to test if it is draining voltage when the ignition is off?

The HU is wired to the ignition power so turns off when key is taken out, and there alternator appears to be putting the right voltage back to the battery as well

Cheers.

 

[AndyMac]

You need a multimeter with an amp setting (about £10 from Maplins. You can either test it at the HU, but easier at the battery. Unhook the earth on the battery and touch one end of the meter to the earth cable and one to the battery earth to complete the circuit. While doing this do not start the engine or even switch the ignition on as most meters would not withstand a big current draw. The reading on the meter will show you what drain is on the battery with everything off. It should be miniscule, maybe 20mA. To drain a decent battery in a few days it would need to be drawing over 0.5a or 500mA. If this is the case then ou need to start pulling fuses until the drain stops. Start by disconnecting the HU if you suspect this as the culprit.
If your only a getting a few mA's and it's going flat in a few days then your battery is fecked.

 

[kaizokuninja]

Well i bought a new battery after the first time that it happened, but then it happened again.
It's just so ironic that it's happening with the new motor and the only relation is the HU. i have a multimete but with all the settings on the thing i never know which one to select with the twisting selector.... =\
P.s cheers for the quick replies dude, it's much appreciated...

 

[AndyMac]

DC amps, DC is shown with a straight horizontal line with a dotted line underneath it, amps is A or mA