Posted by David Sherman on Thursday, December 26, 2002 at 6:12PM :
In Reply to: new battery polarity problem in PW...mystery posted by George on Thursday, December 26, 2002 at 2:31PM :
Lead-acid batteries can get their polarity reversed by being very severely discharged. I suspect this is what happened. You might possibly be able to salvage the battery somewhat by putting it on an external charger at a low rate for a few days. More likely, that battery is shot.
As for the ammeter not working, if you have an old-fashioned generator (not alternator) it may indeed need polarizing. Simply jumper the "field" terminal to the ungrounded terminal of your battery for a second. If the ammeter kicks in, you're done. If not, put a voltmeter on the battery while the engine's running. It should read roughly 13.5 to 14.5 V. If you have a generator system, the voltage should go up when you rev up the engine. If it does, you're probably okay and the ammeter is simply not showing charging because the battery is already charged. If not, or if the voltage is only 12-13 V with the engine running and a known good battery in, you've got some other problem with the generator/alternator or regulator.