How do I find what is causing my car battery to go flat after two days of non use.

Question

I have been told the battery and alternater are in good condition. This means there must be an open curciut somewhere that is draining the power. Has anybody any ideas where to look. I have no access to any volt meters.

Answer 1

Without a meter it is pretty hard to see. The audio circuit or alarm circuits are often culprits. You could try checking where various wires come throuch the bulkhead into the engine bay and make sure non have been abraded as they pass through the metalwork.

Answer 2

>> This means there must be an open curciut somewhere that is draining the power.

You mean closed circuit. Open circuit is disconnected circuit.

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>>I have no access to any volt meters.

Then it would impossible.  You need to take it to a pro.  But why not invest in a volt/amp meter?  They are cheap (Sears / Radioshack).

Basically you disconnect each fuse but measure the AMP (not volt) draining from the battery.  When the amp drops that is the circuit that is draining the battery.

No meter = no diagnostics.

Good Luck...

Answer 3

if you've got an upgraded stereo check if your amp(s) stay on after you turn the key off

Answer 4

pull the fuses one at a time, and when your problem stops you will know what circuit is causing the battery to drain, l had a ford which had the same problem, l found out that the alternator was charging the battery by day but at night it was reversing itself and drawing the power back out of the battery... try obvious first , the light in the boot , and the one in the glove box.  

Answer 5

mmm, check all the bulbs. Ours went flat once when the light in the boot didn't turn off.

Alarm gone faulty ? if you've got a custom alarm, try disconnecting it. If it's built in then you probably can't do that.

Shouldn't be any of the car engine bits, more likely to be a bulb, or radio or something similar.

Answer 6

How old your battery ... could be just a case of a new one

To make sure... charge you battery to full... ie a long trip or charger, remove the battery from the car for a good few days, replace and see if its gone flat.

Bearing in mind any car alarm/ radio/ etc would be taking a small amount of power even when your not using the car.

Answer 7

happened to me... boot light was stuck on

Answer 8

You may have a stuck relay somewhere, or the alternator may have a faulty diode in it (it will still charge the battery, but will drain it when it isnt charging).