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MG MGA - Charging Woes

Following up on my excessive amperage draw after starting. I did the simplest thing first, which was take off the battery caps. The front three cells loked good for fluid but the back three (harder to see and fill of course) took over 1/2 pint of water as the tops of the plates were initially exposed. After filling, the ammeter behaved normally on a 35 mile run. So maybe that was the problem - or perhaps an intermittent control box! Anyway, thanks for your help - I know what to look for if the problem reappears.
Tom Heath

Tom I am not sure what you meant by normal current draw but I would want to measure the voltage being applied across the battery when your engine is revving. A bad control Box can cause the battery to fail by over charging it (boils off the water in the cells), this could have happened to yours originally. If the voltage increases above say about 14.5 volts then it will again damage your battery. Simple check for peace of mind.
Robert (Bob) Midget Turbo

Thanks Bob - I consider normal current draw to be a few amps positive after starting then dropping to the 0 or null position on the gauge after a short while. The needle usually dips into negative territory when applying the brakes with the engine at low revs. I will check the voltage however as I believe this gives a more accurate picture of the behaviour of the generator and control box. I may replace the ammeter with a voltmeter if I can find one that looks correct.
Tom Heath

This thread was discussed on 09/06/2009

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