Classic/Antique Car Repair: 1952 Cranbrook polarity question, correct polarity, filter capacitors

Question
What kind of damage can be done by hooking up the battery as a negatve ground. The car I just bought isn't charging but everything else seems OK. I would have thought the radio would have fried but it works OK. Even the dash guages work. I suspect that the battery is in backwards because it appears to be only months old to look at.

Answer
Plymouths were 6 volt positive ground in 1952.

The way to tell on any car if the battery is in correctly is to note the ammeter reading when you turn on the headlights, with everything else turned off, including the engine.  If the battery is hooked up right, the ammeter will show a discharge when you turn on the headlights. If it shows a charge, the battery is backwards.

Usually doing that ruins the filter capacitors in the radio - so that while it will still sometimes work it sounds really noisy.  The fact that you say the radio still works fine makes me believe that maybe the battery wasn't wrong after all - are you sure about that?

You didn't mention the voltage - I hope no one put a 12 volt battery in it- that would fry numerous things, and could be dangerous!

Putting the 6 volt battery in backwards would make the generator temporarily inoperable, but it will not damage it.  Reversing the battery to the correct polarity may not rejuvenate it, though, you may have to polarize the generator.  If it is not charging after you correct the wrong polarity, momentarily connect the negative terminal of the battery to the "A" (armature, the larger wire) terminal on the generator.  That will draw a big spark, but it won't hurt you or it.  Just touch it on there for an instant, that should wake up the generator.  Be very careful to note if the regulator is sticking after you turn off the engine (it will get the generator very hot, and you'll smell something burning).  Often the regulator will be ruined by reversing the polarity, and this can cause a fire. If you detect this happening, be sure to disconnect one battery terminal when you shut the engine off, until you replace the regulator.  NAPA stills stocks the regulator for that car.

Dick