Magna charging problem?

Have you had checked your alternator ?? sounds like no charge is being returned to the battery ????

Peter

It could be the regulator. An overcharge situation is worse than an undercharge. I'm not familiar with that vehicle, but you probably need to replace the regulator. Unfortunately, Mitsu doesn't normally make this easy. You will probably have replace the alternator or rebuild it if you can find the parts.

I just went through an "overcharge" problem on my son's Eclipse. Battery acid everywhere, from boiling the battery.

While it looked like the regulator was at fault it wasn't.(I ended up bench testing it, and it was OK).

What appeared to be the problem was the third wire running to the alternator, the one labeled "S".

This is the wire that runs directly to the battery, and provides the "sense" circuit for the alternator to monitor the battery voltage. If this wire is open, the regulator in the alternator has no idea of the condition of the battery. The default assumption is that the battery is low and needs a charge. The regulator then turns on the alternator output to charge the battery, via the "B" labeled output lead. When the "S" signal reaches 14.38 volts, the battery is charged and the regulator should turn off the alternator.

A voltage on the "S" lead, greater than 14.38 volts (as measured in a lab environment with a 4 1/2 digit meter) should turn off the alternator output.

I figure I had a loose or bad sense ("S")lead, as the trouble went away after I had disassembled the alternator and tested and cleaned everything inside it, as well as cheched all the wires at the alternator.

On the up side, I did figure out how to test the alternator, and the regulator on the bench, without a car attached.

Thank You.

Barry Lawson