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The mkiv Supra Owners Club

Help isolating the cause for a battery drain


The-Plethora

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I've got a bit of annoying problem lately where my battery which is only about 2 years old seems to die in less than 2 days before the car won't start. I've checked the obvious things like cubby hole light, boot light, doors, etc.

Is there an easy way to narrow this down further or at least isolate what circuit the drain is coming from?

 

I don't have anything plugged into my cig lighter which seems a bit of a commonly overlooked place as some phone chargers drain whilst off. Even if the cubby light was on I would still be suprised if it could drain a big car battery in such a short time so thinking something with higher pull on it. The car hasn't really been anywhere so I discounted the alternator option.

Haven't been able to get to the car this week with other stuff but I hope to have a look this weekend, the more things to check the better :) Any ideas?

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Get yourself a multimeter, and look on Google for 'parasitic drain'. It'll show you how to connect your meter between the battery and car, and through pulling fuses, you'll be able to find the circuit that's causing the drain.

Then it's just a case of unplugging everything on that circuit until the reading drops.

 

Dead easy to do, and very accurate.

 

On my old mr2, where I'd fitted an aftermarket audio system, the stock active amps were drawing a current, causing a drain. Because I'd unplugged the factory radio, and rewired for new iso connectors, the factory wiring wasn't switching the amps off like it should've done.

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Thanks for the help and advice all, I'll give it a go this weekend, I am sure my old man has a multimeter kicking around. It's odd, it's only happened recently and yes it is an aftermarket stereo but it's been in the car as long as I have got it. I thought there might by some sort of 'stay alive' setting on it that maybe I activated but when the powers off, it wouldn't reach the stereo anyway.

 

The car does have an aftermarket alarm that's been on since I bought it. I did debate removing it or rather buying a new alarm and getting the new installer to do the dirty work as I've seen the wiring under the dash. Managed to go home at lunch, it had been fully charged 1 day ago and was already cactus as the aussies say. Will let you know when it turns out to be something simple as these things usually tend to be :)

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I had the same problem, could have been alarm or radio, I still couldn't find out what was causing the problem.

I bought a solar charger and fitted to the inside of windscreen with Suction cups, using crocodile clips to battery. its been ok since.

http://www.ebay.co.uk/itm/BRAND-NEW-1-5W-12V-Solar-Trickle-Car-Battery-Charger-PS-A015-/190741682264?pt=UK_Gadgets&hash=item2c69171858

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Another thing that might be worth doing, is fully charging the battery off the car, and taking it to a battery specialist - or halfords if you have no other option, and get a load test done it. It's normally free, and will rule the battery being duff out

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Another thing that might be worth doing, is fully charging the battery off the car, and taking it to a battery specialist - or halfords if you have no other option, and get a load test done it. It's normally free, and will rule the battery being duff out

 

Good point by Gaz, some do fail, especially if they have been flat and charged up again a few times.

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