From: John De Armond
Subject: Re: Interesting battery failure
Date: Mon, 20 Dec 1999 04:27:07 EST
Mickey Lane wrote:
> While toting trash to the recycle center, the golf cart died.
> I thought the motor had quit but when I took a voltmeter to it, I discovered that one of
> the batteries was the culprit. The cart has six batteries in series. At 6 volts each,
> that's 36 volts.
> With no load, the battery bank measured ~36 volts. When I tried to put the scenery
> in motion, the voltage dropped to about 8. Checking each battery in turn found one
> that went from about 6 at rest to *minus* 15 or so under load. It was in the middle of the
> array so what was happening was that the load was effectively re-ordering the sequence
> of the batteries.
> Has anybody ever seen this?
Pretty good indication that a plate pack broke free of its connector
inside a cell. The lead connectors build up the same sponge lead
and lead oxide as the plates but as a thin film. Absent the plates,
this film will generate the same EMF as the plates and will supply
the few microamps it takes to make your voltmeter read. Of course,
this film has no capacity and so when you load the battery, that
cell shows up as an open. A good clue to that is your first
sentence - the cart just died while in use. Did you hit a bump of
some sort? Sounds like it's time for a trip to Sam's :-)