On Wed, 31 Aug 2005 17:05:01 -0500 Ryan Underwood
wrote:

I have two hardly-used UPS batteries that were stored two years ago after
the UPS was destroyed in a storm.

I was thinking of using an automotive 14V trickle charger to attempt to
charge them to the point where the UPS would hopefully accept them back.
Does anyone know if an automotive trickle current is within the normal
range of charging current for a sealed lead acid battery?

I would try the automotive trickle charger. As long as the charge rats
is small (try 1% of the AH rating of the battery) then you should be
okay. When you do this, the battery voltage should come up to 12V
within 1/2 hour. If it does not, then the battery probably has several
shorted cells and can't be fixed.

If the battery comes up to 12V at the 1% charging rate, then just
leave it charging at that rate until the voltage gets up to 14.1V.
This may take a week or 2, depending on how badly sulfated it is.

Once the battery voltage while charging a the 1% rate rises to 14.1V,
you should be able to put the batteries in the UPS and proceed
normally.

Note that none of this insures that these batteries will have a lot of
capacity once charged. You should probably run a "test" power outage,
just to find out whether they are going to be useful.

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Jim Adney
Madison, WI 53711 USA
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