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View Full Version : Anyone know how to load test a battery?



Aegis
12-01-2003, 06:54 PM
I think I finally isolated our emag woes to a faulty battery or charger, probably the battery. The Emag battery was dropping voltage like a stone when attached to the mag, even with an 18.5V starting charge. I was worried about a short or bad connection somewhere.

Finally remembered I had a meter that measured amps. The emag was pulling .001 amp at rest, which I believe is 1 milliamp. That means a charged battery should power the mag at rest for 650 hours. It seemed to pull around .05 when firing, hard to measure the burst.

The emag battery would drop .1 volt every 1-2 seconds when connected.

I put two 9 volt batteries in series to get 18.87 volts and hooked it up to the mag. The voltage was stable, no drop over the several minutes I watched it, and the amp draw was the same.

Not sure if this is of any use to anyone, but all the discussions I have read seem to support the idea that if the battery is charged to the correct voltage, it is OK. That does not appear to be true. While this is not much of a load test, it did help me determine the marker was OK.

athomas
12-02-2003, 02:38 PM
Use a 250 watt light bulb as a load. The resistance is 58ohms. The current draw should be about 300mA. Connect your battery across the lamp. Measure the voltage before and during the connection. You should get a good feel for the capability of the battery pack. If the battery pack voltage goes way down then you have a problem with the capability of the pack.