I recently acquired a used riding mower. I figured it was dead, so hooked it up to a trickle charge overnight. Next morning, still totally dead.
I stuck my voltmeter on it, and measured -11.8V. Check the leads on the meter, and checked the meter against a AAA alkaline. No, the meter is working fine...the battery has a negative voltage.
To confuse matters somewhat, this battery has a red sticker next to the "-" molded into the plastic case. I'm not sure what to make of that.
So the question is this: is it possible through some mechanism to reverse the voltage polarity on a lead acid battery? Or, is this a case of cheap Chinese manufacturing?