I have a back-UPS 400 with a useless gelcell. However, touching
terminals of a fully charged and healthy gelcell to the battery
leads causes mega amps to flow, so something is likely fried.
Interestingly, the dead battery has about 10.5 volts on it,
in-circuit, no current!

Anyone got a schematic or wisdom to share? / thanks / mark


Ed Huntress wrote:

"Too_Many_Tools" wrote in message
oups.com...

I am the "lucky" owner of a number of older UPSes.

So what can a person build out of these?

The batteries are for the most part dead but the remainder of the
components seem to be in good condition.

Any suggestions?

Thanks

TMT


If you can get your hands on a copy of the 2005 ARRL Handbook, there are
several suggestions in there (radio-related, but you can improvise from
them), and some information about UPS's.

One is a charger for 12V storage batteries in general, including car
batteries. Another is an emergency power supply (you can just run two wires
to your car battery, or a bank of deep-discharge batteries wired in parallel
if you're so inclined). Depending on the model you have, you can get 160 W
to over 300 W of 120 VAC and/or 12VDC from them.

Mine (an APC Back-UPS 600) is now wired to an old car battery. It will run
my computer for a lot longer than the old gel-cell that came with it. Since
we're on the end of a power transmission line, it gets a fair amount of use.

--
Ed Huntress

In article , Mark
wrote:

I have a back-UPS 400 with a useless gelcell. However, touching
terminals of a fully charged and healthy gelcell to the battery
leads causes mega amps to flow, so something is likely fried.
Interestingly, the dead battery has about 10.5 volts on it,
in-circuit, no current!

This is the classic symptom of a 12-volt lead-acid battery with one cell
shorted. Hooking a 12-volt battery to a 10-volt battery will draw lots
of current, as observed. Replace the old gelcell battery with the new
one; do not keep the old gelcell in the circuit.

Joe Gwinn

Um, I didn't make myself clear, I guess - I took the old one out,
clipped to the new one, instant heat. Big heat.
I'm guessing that there's circuitry which avoids draining the
(bad) low voltage one past a certain point. I'm also guessing
that a fully charged battery (the one I tried to hook up) enables
current flow, and that perhaps the input of the invertor section
is shorted. I didn't feel like leaving a perfectly good 17A-hour
battery to fry itself and the surrounding wires etc.....

BUt thanks for the response / mark


Joseph Gwinn wrote:

In article , Mark
wrote:


I have a back-UPS 400 with a useless gelcell. However, touching
terminals of a fully charged and healthy gelcell to the battery
leads causes mega amps to flow, so something is likely fried.
Interestingly, the dead battery has about 10.5 volts on it,
in-circuit, no current!


This is the classic symptom of a 12-volt lead-acid battery with one cell
shorted. Hooking a 12-volt battery to a 10-volt battery will draw lots
of current, as observed. Replace the old gelcell battery with the new
one; do not keep the old gelcell in the circuit.

Joe Gwinn