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Path: utzoo!linus!philabs!seismo!rlgvax!cvl!umcp-cs!fred
From: fred@umcp-cs.UUCP
Newsgroups: net.auto,net.rec.boat
Subject: Re: Marine batteries
Message-ID: <1361@umcp-cs.UUCP>
Date: Mon, 1-Aug-83 19:59:58 EDT
Article-I.D.: umcp-cs.1361
Posted: Mon Aug  1 19:59:58 1983
Date-Received: Wed, 3-Aug-83 03:45:51 EDT
References: <339@hou5f.UUCP>, <2065@alice.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 24


	From: wookie@alice.UUCP

	Ni-cads . . .  tend to crystalize if left on the charger
	all the time and will not work at all unless you zap them
	with a very high current for a short period of time (seconds)
	to break down the crystals.  WARNING: This is a dangerous
	practice as the battery can explode throwing potassium
	hydroxide all over the place!

					Keith Bauer
					White Tiger Racing

I once sucessfully revived my rechargeable ni-cad electronic flash
unit by doing just this. I used a small capacitor (about 30 mfd.),
charged it from the flash unit's recharger, then touched it to the
terminals of the flash unit, but with the polarity reversed. It's
now accepting a full charge, just like new. I imagine that doing
this with a much larger battery could well be dangerous, but there
doesn't seem to be much danger with the small (C-cell size) batteries
in a portable flash unit. Besides: no one warned me. I suppose that
another safety factor is that the total charge in the capacitor is
extremely limited, so the reverse current will only flow for a
fraction of a second, not long enough to cause an explosion.