Yet another battery drain problem
 

For quite a while, my 04 WRX wagon has been failing to start due to flat battery when it's been idle for a while.

I did a little diagnosis today - wired a multimeter into the battery circuit then started pulling fuses. Almost immediately pulled a fuse that reduced the draw from about 0.02A to virtually nothing.

This was fuse 12 under the bonnet which is 15A and according to the owner's manual covers "clock and interior light" (The 0.02A draw continues when the interior light is switched to off).

When I pull that fuse, the car won't start. When I restore that fuse, the alarm chirps. So I suspect the alarm is also on that circuit and could be the source of the excessive current draw.

Can anyone confirm? Is it time to replace the alarm (standard Sigma M30)?

Thanks in advance for any guidance.

Anything aftermarket also connected to that circuit?

No, everything is factory standard. And no tracker fitted.

How old and what condition is your main battery??
Do you "condition" it??

Battery conditioner

0.02amps is fine... I would say anything under 0.06amps is ok anything above is a problem.

The battery is less than 12 months old. I don't condition it but I charge it up with a CTEK charger regularly.

The most recent episode was 19 days at Luton airport - I had charged it just before leaving home and it was completely flat on my return to the airport.

Most Ctek chargers have a recondition setting/s - maybe worth a try.

0.02A is only 2/100th of an Amp, so that drain for 100 hours is 2A

100 hours is four days and four hours. So a 60 A battery ought to last well enough, but maybe 19 days is a bit long.

You could pull that fuse when parking up, or organise a small switch in the circuit?

Alternately, get hold of a solar charger for long periods parked up?

Thanks for all the thoughts - I did run the battery through a CTEK recondition overnight and the voltage measures higher today. Pulling the fuse when it will be parked up for a while also seems sensible.

I have also acquired a solar charger (there's another thread on here about that).

I've had this recently with mine. Had it in the auto electricians until they got to the bottom of it. They traced the wires back after disconnecting the tracker and disconnecting all the other parts on that fuse. It ended up being a small relay at the back of the internal fuse box under the dash. You have the remove the fuse board to see it. It was the one for the starter. Since sorting that it has no draw. If I remember it was a small blue wire with dashes to the relay that has the draw