The MGA With An Attitude
Keep Your BATTERY (Batteries) CLEAN - ET-129

Lucas group 17HF battery On 6/20/2012, Brooks Schneider in Rochester, NY wrote:
"The MG wouldn't turn over today (fuel pump was working). I have a single group 26 battery in it and have converted it to negative earth. I had my generator rebuilt about 5 years ago and also put in a new control box at the time. When I pulled the battery cover off, I noticed a quite a bit of corrosion on the positive terminal after only being hooked up for about a month. I cleaned the terminals up and have the charger on it now, while I have the cables off. I'm guessing this corrosion is telling me something, but I'm not sure what. Any thoughts"?

You need to keep the battery clean on top. Also check charging voltage with engine at road speed (3000 rpm). Charging voltage at the battery posts should never exceed 14.5 volts. When you switch on headlights, heater blower and wipers, the generator will do good to make 13.5 volts at the battery posts (although an alternator could do much better).

When it overcharges it can spit a bit of acid out through the cap vents onto top of battery. The acid is electrically conductive, especially if there is some dirt mixed in with it. You can easily test this with a volt meter. Put the black lead of the meter on the negative battery post, and touch the red lead on top of the battery in between the posts. Moving the test lead closer to the negative post will show lower voltage. Moving the test lead closer to the positive post will show higher voltage. It should always show zero volts on top of the battery. If you find any voltage at all on the top surface, it needs to be cleaned.

Wet the battery with water. Sprinkle baking soda (bicarbonate of soda) on the battery, and scrub with a stiff brush. Any acid present will make the stuff fizz and bubble up. When it stops fizzing, rinse well with water. Then you can check the top surface for voltage again.

You can get the anti-corrosion kit that consists of little red and green felt rings to put around the battery posts. The felt rings are chemically treated to neutralize acid and will greatly reduce corrosion around the battery terminals.

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