MEP 802A battery drain.

Gentlemen,

A few years ago, I purchased a MEP 802A with 26 hours on it, that constantly and completely drains the batteries down. Sometimes it takes weeks, sometimes a few days. I have replaced them several times over the last few years. Even if I turn off the master switch on the left side panel, they go dead. Is there something that can be draining them that I am unaware of? I cannot figure it out.. I have other MEP 802s that start even after 6 months of sitting..

Thanks in advance, Rick

How do you leave the dead crank switch? Do you always leave it ON, or OFF?

I've done both, but usually I leave it off.

More than likely the alternator. The rectifiers can short and cause the batteries to drain fast.

jamawieb said:

More than likely the alternator. The rectifiers can short and cause the batteries to drain fast.

Click to expand...

How can I test that? Or should I just remove the connector off the alt, and see if the batteries still go dead?

Disconnect the positive battery lead going to the starter, connect your multimeter set to the 10 amp scale with one lead on the battery terminal and the other on the cable end. This will tell you if it has a draw. If it does you can disconnect the power lead from the alternator to see if that is the problem. You can also run a diode test on the alternator power lead. It should measure voltage one way and not the other.

Does it have a solar panel and charge controller?

My 803 has been doing this and I suspect the charge controller. At least I measure no draw with the controller disconnected and I get a slight draw with it connected. I am leaving it disconnected for a while to see if they go dead again.

You can also test for a drain with a test light.

Disconnect the positive on the battery and connect a test light in series. The light will be lit when theres a draw. Now you just have to figure out where its coming from.

Normaly on a vehicle you would just go around and start pulling and replacing fuses. On this generator there are not many fuses so your looking at pulling and replacing wires.

Agreed, I recently had same issue with one of my 803A's, bad alternator drained batteries in a day or 2. Also used the test light method. just disconnect the wires ( probably start with the wire feeding to the left of the regulator ) and see if the test light goes out.
If I recall correctly, putting the dead crank switch in the off position does not stop the draw if the problem is the alternator and I don't think pulling the alternator fuse does either, but don't quote me on that....

You could always read the TM. I would lay good money on the battery charging alternator.

There is no "Master Switch" on these sets. Read the schematic. The hot wire to the alternater goes straight to the power source. The diode in the alternator is there to prevent just this problem.

Light in the Dark said:

How do you leave the dead crank switch? Do you always leave it ON, or OFF?

Click to expand...

TM 9-6115-642-10 0003 ENGINE STARTING SYSTEM – CONTINUEDthrough the starter solenoid which in turn is controlled by the cranking relay. The starter then engages the engine flywheel causing the engine to turn over. For engine starting, the DEAD CRANK switch must be in the NORMAL position, the DC Control power circuit breaker must be pushed in, the EMERGENCY STOP SWITCH must be in the OUT position, and the MASTER SWITCH is moved to the START position. The cranking relay is then con- trolled by a circuit consisting of the crank disconnect relay and crank disconnect switch. As the engine accelerates to the preset speed (sensed by the magnetic pickup), the crank disconnect switch opens and de-energizes the cranking relay to stop and disengage the starter. The starting sequence may also be stopped by moving the MAS- TER SWITCH to OFF. The engine may be cranked without starting by use of the DEAD CRANK switch. With the DEAD CRANK switch in the CRANK position, the cranking day, starter solenoid and starter motor are energized without activating any other starting or control function.

I’d turned mine to off, a week or so later couldn’t figure out why it wouldn’t start, much less just turn over.

Reread that passage and voila.

My batteries on my 802a drained down to nothing in about 6 weeks. A month out on a solargizer and they’re keeping charged. Working on an 803 right now (soundproofing, cleaning tank, painting, replacing screws), will circle back to the 802a.

Thanks for posting.

Norm