Hello all,


I need a list of things to check to help me sort what is causing my battery to drain so quickly. Here is the scenario: I replace my old battery with a new one and all appears to be ok....the car sits for about 3~4 weeks before it is started again. The new battery is dead ....

I can put a battery charger on it for about 20-30 minutes at high boost and it will start.


So far, besides the battery, I have replaced the battery cables. - still no change. I plan to pull the altenator off and have it tested. Besides testing the altenator, what else can I check?

I dread electrical system problems more than other types of problems....

Any ideas?

Thanks,
-Mark P.

An excellent troubleshooting tool is a test light, of any kind, whether it be a "real" test light or a back-up socket with a bulb.

Unhook the ground cable from the battery and hook the battery to the test light and the cable to the other test light lead. The brighter it glows, the more current being drawn.

Modern radios have "keep alive" memory and a clock, so maybe 10-20 milliamperes will be drawn. One doesn't want more than 50 milliamps with everything else off.

Back to the test light, pull fuses and the like till it barely glows, ie, radio. You might even disconnect the red wire from the alternator to make sure its not discharging the battery.

Does it spark when you connect the red wire to the battery terminal. That is a pretty good way of quickly seeing if something is feeding off the battery when everything should be off. You can also get a battery quick disconnect, I use it everytime I park the car for long periods of time. Makes a nice theft deturent system.. At least they would have to put 2 mins into looking around to figure what is going on before they hot wire it. :)

Thanks guys!

I'll get a test light and try out what you suggest.

-Mark P.

Does it spark when you connect the red wire to the battery terminal. That is a pretty good way of quickly seeing if something is feeding off the battery when everything should be off.:)

Sparks are good way of check for a current drain, just don't rely on the intensity of the spark to determine how much current is being drawn. You can make a large spark with a very small current load, depending on the type and condition of the conductor material.

Larry

http://hawkpichost.com/ims/album.php?u_id=47kT1HB

If you still have the external type voltage regulator, check that. I had the external voltage regulator on my 69 fail. When running, the alternator would charge. But when shut off, the points would stick closed and allow the battery to back feed and energize the alternator coil. The alternator dissipated the current as heat. A new fully charged battery would be fully discharged in about 3 days. With the key OFF, in a VERY quiet enviroment, Listen very closely to the voltage regulator. If it sounds like a tiny transformer humming chances are that regulator has failed.

Of course, the test light and/or meter would pinpoint this spot on!

Oh, and, be carefull with all the "Spark Checking" around the battery. The gasses can be Explosive.....Jb