Ghost Chip wrote:

It is possible to use a welder as a charger. You must keep the current
below the 100% duty cycle rating of the welder and stop charging when the
battery reaches full charge. Of course DC is required, either from the
welder or from your diodes. For lead acid batteries, a good charge
current
is about 10% of the amp-hour rating of the battery. 100 amp-hours --- 10
amps charge rate. Don't charge beyond the point when the electrolyte
reaches 1.280 specific gravity, (1.270 warm).


Just a bit off topic ... According you what you had mentioned above, a good
charge current for a lead acid battery is about 10% of the amp-hour rating
of the said battery. When I opened up several (different brand) UPS rated
at 500VA max, they all have a single 12VDC rated @ 7A battery (presumably
gel battery). I would presume it would be alright to replace this battery
with a 700 amp-hour or greater lead acid battery found in most SUV or
trucks so the UPS can be used to provide a longer and an uninterrupted
electrical power for a 200 watt load, i.e. TV, all night long during the
outage. Once the electricity is back, this battery can be automatically
charged to full by the UPS. Since any existing UPS has a built-in circuitry
with a current-limited and auto-charge capabilities, one does not have to
worry of over charging the lead acid battery to cause an explosion. I hope
anyone out here can confirm this so I can start start making the extension
cord and use it to replace the worn-out battery with a lead-acid battery
for my 350VA UPS used by my 32" TV. That way, I can still be able to watch
and follow up with the weather channel in case of a power outage due to the
storms.


A trickle charge rate can be left on for long periods of time. This is
about 1-3% of the amp hour rating.

CAUTION:
If you don't limit the current, the battery can explode. If you
overcharge,
it will warp the plates and ruin the battery. If you exceed the duty
cycle
of the welder, you can burn it out or severely shorten it's life. Know
what
you are doing and use good common sense and caution and it can work. I've
done it.

"Cory B" wrote in message
om...
Hi everyone, I have a very important question that needs a good answer
(such that I don't kill myself/start a major fire)

I have a forklift that is run off of batteries, 36 Volt... I beleve
they are in series linked positive to negative(series right???) There
are two posts for each positive and negative so that there are four
posts on each battery. There look to be a total of 18 cells, which
would be 2V each.. These are quite large..

The problem that I have is my charger I bought with it is three phase
(label indicates that it is "cycle phase"?? does this mean anything
important??) and it produces 36 Volt at 180 DC Amp..

I have a Lincoln welder that is 220 operated, and has an output of 40
Volt Switchable from AC/DC, and selectable 10-220 amp.. I am thinking
that if I were to use a 4 Volt inline resistor, and somewhere around
100 amp it should charge the batteries quite well, although I am not
an electronics expert of any sort and I really need some advice here
as to what parts to use, how to wire this baby up and feedback as to
just how crazy I might be..

Thanks in advance everyone,
Cory Boehne.