Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Wed, 07 May 2003 19:30:12 -0400
Message-ID: <redirect-2336873@logan.com>
Reply-To: "Dan Schaefer" <dfs155@earthlink.net>
From: "Dan Schaefer" <dfs155@earthlink.net>
Subject: Re: Electrical System - Battery Charging
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Brent wrote:

"Therefore there is another term for "desulfating", it is called "Charging".
ALL battery chargers, when used on lead acid batteries, by definition,
"desulfate" the batteries they are charging."

True, Brent, but not the whole story. Long story short, there are levels of
sulfation that can form (for several reasons) that will resist reversal by a
standard charger. Allowing a lead-acid battery to sit in the discharged
state for as short a time as a week or two is the primary reason for the
formation of the difficult (if not impossible) to reverse sulfation, while
other reasons are secondary.

Working with Dr. Dave Vutetakis (a battery guru) of The Battelle Institute
during development of a Sealed Lead Acid Battery (SLAB) for the B1-B, I
learned that the only way to reverse the destructive type of sulfation was
to use what was referred to as a "Hot-shot" charger, and then only with
spotty results. The Hot-shot charger (for a 28 volt battery) is basically a
100 volt dc power supply with a resistor in series sized to limit the short
circuit current to less than about an amp (for a 15 - 20 amp hour battery).
Destructive sulfation reversal, if successful, takes up to a couple of days
and the only way to tell if it worked is to do a deep discharge followed by
a normal charge and then a capacity check. If you're lucky the battery may
recover most of it's capacity, some however never do and it's probably due
to the severity of the sulfation.

Bottom line, I guess is, don't leave your battery sitting around in a
discharged state - fly it or otherwise keep it topped up as required and,
barring other abuses, it should last quite a while.

Dan Schaefer