Re: (ET) batteries

["David Roden" <etpost drmm net>]

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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