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



To Dave Klinger, What is the spec for the large diode? The light bulb
and is it hooked up in series or parallel with the battery?

Tony Lam


I have used this method many times  over the last 40 yrs with good
success. Beware of the shock hazard when directly wired to the mains.
Use a diode with at least 200V rating and amperage in excess of the
ballast lamp current.

Robert  LeClercq

How about a schematic Robert?

Paul Lamar


I've always had pretty good luck just jumpering to another charged 12V
battery.  Once the voltage comes up a bit, it will then take a charge.
You can get the little transformer plug-in chargers that will also
desulfate for <$50.  To correctly desulfate can take a long time but it
will result in a usable battery.

Todd Archer