Battery Draining When Car is Off

skywalka

skywalka

Member
Hi guys,

Finished work the other day & my battery was flat as. Turning the ignition did absolutely nothing. No cranking, no ticking, no sound! Not even the clock was on. The warranty had expired a while ago so thought that must be the problem.

Bought a new heavy duty battery and checked that the car started fine. Went to drive it for the first time this morning and exactly the same thing happened.

I’ve never really encountered this and would love some suggestions on how to proceed.

Thanks.
 
Sounds like a curious problem.. To diagnose from here, youll need a ‘clip on’ ammeter to measure current draw. I am assuming the battery is drained when you attempt to start the car.

Charge the battery.
Ensure all possible consumers are off, open bonnet and close all doors, key out of ignition.
Put ammeter over positive cable and read the draw. If you have a parasitic draw, you will notice a value higher than 80mA.
(If you have a value lower than 80mA, check all your terminal connections and body fuses. )
From here you can either put the ammeter over individual positive wires to trace the component that is draing your battery, or you can leave it in place over the main cable and unplug the fuses and relays in the engine and body fuse boxes. Disconnect one at a time and check the ammeter to see if the draw is gone.
You may find multiple culprits.
 
Thanks for the replies guys.


I’ve been disconnecting the battery whenever I leave the car for an extended period. But last week I forgot to disconnect it while at work but to my surprise it started fine. It was a 7 hour day instead of the usual 9.5 but considering how dead the battery had been in the past I don’t think the problem was present.


This leads me to suspect the alternator which I’ve had to give the occasional tap with a hammer over the last year.


These are DC connections aren’t they?


I managed to source a clamp meter from a friend. It only measures a minimum of 0.1A so doesn’t seem accurate enough. When I’m just holding it the reading fluctuates by 0.1A. I think it must be designed for mains power etc. I think I’ll bite the bullet and buy one designed for automotive use. Can anyone recommend one?


Thanks again.
 
most cheap meters from jaycar will measure mA's but you'll need to put them in the circuit, not a clamp meter.
 
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