Troubleshooting a drain on the battery

[JimG]

i'll offer a suggestion about tracing down a power draw from a battery, but i will admit up front that electrical issues and trouble shooting are not my strong suite....i have not used this process but it seems like it should work...others with more electrical knowledge than me will chime in if this is not correct....turn everything off and measure the voltage across the pos and neg battery terminals with a voltmeter....then pull a fuse from the fuse box...recheck the battery voltage...if the circuit that was controlled by that fuse was causing the power draw you should see a slight increase in the battery voltage once the fuse for that circuit was pulled...if there was no change in the battery voltage replace that fuse and pull the next fuse in the box and retest the battery voltage....continue this process until you discover which circuit is responsible for the power draw on the battery...then you can check each component in that circuit one by one and the associated wiring to locate the source of the problem...

cliff

A strong battery with a few hundred mA draw on/off may not show any voltage change.

A more absolute method would be to use the current function of the meter (may require a better meter). Start with the 10A setting just in case, and then move to the mA setting. For those that don't know, remove all positive connections from the battery and connect them to the black meter lead, then connect the red meter lead to the positive battery post (digital meters actually don't care about polarity, this way shows positive current flow).

Then proceed as you describe.

 

[troc]

Check alternator a shorted diode pack will draw current. Meters are great but a easier way is to put a test lght in series with battery cable. a glowing test light indicates current flow. Start opening breakers /lifting wires untill glowing stops. keeping in mind normal parasitic draw co moniter/clocks/electronics