"Larry" wrote in message
...
"Eisboch" wrote in
:

According to several sites that I just read .... AGM batteries can
indeed be desulfated if they are not too far gone. Worth a try
anyway.


Notice the part where the current charger "won't charge them"? The
electronic chargers, like my 40A/100A Vector, won't start the charging on
a dead battery because the computer can't seem to tell what to set the
voltage to unless there is a residual voltage to measure, unloaded. My
neighbor had a dead car battery and, bigshot me, took the big Vector (now
called Black and Decker as they bought the company) over to his house.
It refused to start on the dead battery. I came back and got my trusty,
old Schumaker SCR charger and left it pumping his dead battery for an
hour to get the voltage to come up. Swapping chargers to the
Vectorbeast, again, it started charging normally. Once charged, we left
it on refurb overnight to desulfate the plates with its pulses. The
battery wasn't left uncharged over a few hours. His kids left the
interior lights on all night and noone noticed. It was really dead!

So, I suspect his discharged cells are why it wouldn't start charging.
The computer didn't understand. From that info, he needs a new
battery....BEFORE the damned thing strands him in the middle of nowhere
with no starting power to get home.....ok? If he has any brains, he'll
buy a wetcell we can TEST!


I agree and have had the same experience. It was not clear however if the OP
was using a conventional charger or a smart charger. I've had "dead"
batteries that would not charge from a conventional charger either, simply
because of sulfated plates and the resultant high internal impedance.

Also, I've had more than one experience with the Vector or smart Schumacher
on dead batteries.
You are correct ... they will try for a while, then default to an Error.
However, I discovered that if you just unplugged them and start it again,
eventually they will raise the battery voltage enough to continue through
the normal, 3 stage process.

Eisboch