In a message dated 9/22/01 8:48:50 AM Pacific Daylight Time, cooper@BQMLAW.COM writes:
With an aux battery installed by me. I did beef up the wiring (to 8 gauge) and I did beef up the relay. I also have been over the grounds and all connections. It seems that when the alternator is running, everything is fine and the batteries both charge. However, the aux. Battery drains very quickly. I replaced the first one which had worked nicely for a couple of years, and the second also drains quickly. I am not at the van now, so I cannot recall what the specs on the aux. Battery are, but suffice it to say that it is a marine deep cycle of decent size and amperage. How do I test to see if there is a drain. The items connected to the aux. Are, in addition to the usual westy stuff; a radio tape head and a cd changer, one additional dome light, a large cpu fan. None of these items is left "on". The wiring to the cpu fan (I like it because its quiet) is a very small gauge.
How do I go about this? Does anything sound obvious?
Jonathan R. Cooper
Brzytwa, Quick & McCrystal
900 Skylight Office Tower
Cleveland, OH 44113
John, disconnect the ground and hook a test light from the disconnected cable to the battery ground post. If the test light lights up, and all loads are off, then you have something in your electrical system that is using power.
By disconnecting one thing at a time, you can find the culprit when the light goes out. This is how i recently found the power drain caused by improper wiring in a Vanagon gas heater.
And if the test light doesn't go on, the testing the battery should be as follows:
Take a voltage reading, check the electrolyte level, charge the battery (with ground strap off),
and then let the battery rest for 24 hours (rest means don't charge or discharge) if rested voltage is blow 12.65 volts, then the battery (or charger) is defective.
If you have a battery rested voltage of say, 12.4 or lower, then it isn't able to hold a charge.
Avoid the cheap load tester which is inaccurate.
A hydrometer will show if one or more cells are bad.
Disconnect charger when amp reading is one half of initial reading (if it starts out at 10, shut off at 5 amps. leaving it go to zero overcharges the battery.
Also, beware of cheap steel battery cable connectors which are invading the market. Steel has 1/50 th the conductivity of copper-your batteries will never fully charge, and the terminals will rust. A magnet will easily show you if any replacement cables you have steel connectors.