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Re: (ET) batteries
On 17 Feb 2007 at 11:46, Neil Dennis wrote:
> have you ever thought of trying a desulfator ? I think the trickle
> charge long term causes sulfation.
First : Although there are some folks who are passionate believers in
"desulfators," I have yet to see any solid evidence that they really do
anything that a proper equalization charge won't do - except line the
pockets of their salesmen. The technical explanations sometimes offered
for
what they supposedly do are just plain bizarre. That's the Readers Digest
version; I've posted longer and more detailed discussions of this matter
many times before. Check the archives if you're interested.
Second : You're correct that long term uncontrolled charging is indeed
damaging. However, the damage is caused by grid corrosion, not sulfation.
To clear something up, sulfation is a normal process in operating a
battery!
What you want to avoid is >permanent< sulfation. This is a relatively
rare
condition which results from chronic undercharging, or from long periods
of
inactivity (many, many months or years) when self discharge drains the
battery and it is not recharged.
The sulfate which forms as a normal consequence of using the battery is
changed back into lead by charging. But if some of it is left for too
long,
as in a chronically undercharged battery, it forms into crystals which
resist the chemical reaction of charging. These crystals eventually flake
off the grids and thus make active material unavailable to participate in
the charge, diminishing the battery's capacity. Eventually the layer of
shed crystals accumulating in the bottom of the battery may reach the
grids
and short one or more cells.
Although there are ways of dealing with the cell shorting, this form of
sulfation is NOT reversible. Not by electronic gadgets, not by chemicals.
The lost capacity is gone forever.
To answer the original question, AGM batteries such as Optimas do indeed
have lower self discharge, so they might help this situation.
Or just skip the maintainer; most of them do more harm than good.
Just charging the battery every few months is a much better strategy (a
couple times a year for AGMs). Mark your calendar in March, June,
September, and December, and run the charger for a couple of hours when
the
day comes up.
Disconnect the battery when the car isn't in use, assuming there are
constant energy users such as clocks and engine computers in the MG. Keep
the battery clean, dry, and cool. Simple stuff, but it works.
David Roden - Akron, Ohio, USA
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