anybody know how to resurrect a dead motor cycle. apparent it sat
around too long. Voltage is about 8 volts open circuit. Won't take a
charge. Is it just trash?
Paul Lamar
I've been told to clamp it in a paint shaker for a few minutes. This
is supposed to break up the sulfate crystals....
JimR
That interesting. Thanks. I'll give it a try.
BTW I have not been running the RV4 lately so that scared me and I
took the batteries out to trickle charge them. They both appear to
be still OK.
Paul Lamar
I used to sell used industrial-sized uninterruptible power supplies,
and I got reasonably good at resurrecting expensive lead acid
batteries over the years. I use the same setup I use for repairing
electronics, taught to me by a friend who grew up repairing
televisions and radios in his uncle's repair shop.
To get the battery charging, you generally need decent voltage,
ideally several thousand volts. I've never had an industrial pulse
power charger, so instead I took a cheap extension cord and installed
a big ceramic diode in one leg, along with two alligator clips. I
connect the alligator clips to the battery, giving it rectified
pulses off the wall outlet. The power goes through the battery into
an old lamp with an incandescent light bulb. The bulb will glow when
the battery begins to charge, usually after several hours, and you
can switch to a bigger bulb if you're charging a bigger battery. As
an added benefit the bulb will limit the current, preventing your
battery from blowing up.
I've used this arrangement for resurrecting very small to very large
batteries, including car batteries and electric forklift batteries,
and the ones I kept have lasted for years afterward.
Dave Klingler
Can I ship you a couple of dead batteries?
Paul Lamar
Hm. The last cord I made is buried in one of three large warehouses
about 60 miles from here, but they're not hard to make. I'll nip past
Radio Shack and see whether they still carry a diode or a bridge
rectifier that will work. It might be much easier for me to cut up a
lamp cord and make you one.
Electronics repair guys have probably coined a name for what I'm
describing. They're handy for finding shorts, where you want a little
bit of current in a circuit but not so much that a fuse will blow. The
incandescent light bulb is a cheap and magical diagnosis device, and the
whole thing only costs a few bucks plus an old table lamp.
Generally speaking, you'd like to just get the battery to start
charging, i.e., when the lamp gets nice and bright, the battery is
drawing current. I used a 60W bulb for most 12V batteries, and then
moved them off to a regular car charger after they started charging well.
My friend is a pretty good power supply engineer, and he eventually
designed and built himself an adjustable frequency desulphator that goes
on up to around 10,000 VAC, using audio components, IIRC. I got out of
the UPS business about eight years ago. If I hadn't done that, I might
have pursued a better arrangement, but my poor man's desulphator works
pretty well for about 80% of the dead batteries I've had. I've been
surprised at my success - some of those batteries had sat around outside
for a decade or more.
By the way, just leaving a battery on a new solid-state trickle charger
for a few days, then exercising it, works for me quite often. I'm using
a 6-year-old battery right now in my car that sat around dead for about
four years and just required a little exercise and patience (several
cycles) to resurrect. Of course, if the plates are shorted, you need to
blow the debris back into solution with higher voltage than a
conventional charger will supply.
Dave Klingler
Will my 560 DC supply work?
Paul Lamar
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