Fortunately, on the other hand, an ailing cell can often be shocked back to life if you force enough current through it to cause the short to burn away. Once that electroshock therapy is finished, the battery can be recharged for normal operation.
ILLUSTRATION: MOTHER EARTH NEWS STAFF
Nickel–cadmium batteries can be
an economical (and environmentally beneficial) alternative
to conventional cells . . . if you get their full life.
Building a Nicad Battery Reconditioning Machine
In ten short years, rechargeable
nickelcadmium batteries have become commonplace modern
conveniences. They now power everything from razors to
radios, and when one goes dead you simply plug it in for a
recharging. (See MOTHER EARTH NEWS issue 95, page 50 for instructions on
building a charger.) A time comes, however, when the
battery simply won't hold a charge any longer
and — presumably — must be replaced.
Unfortunately, many nicads
get deep–sixed before their time. In most cases, more than
one cell is needed to power a device, and one bad cell can
drag the rest of a perfectly good battery down. Most often,
the problem is an internal short, which bypasses current
around the affected cell. The other cells are actually
fine, but there's not enough capacity for the job, so the
battery gets thrown away.
Fortunately, on the other hand,
an ailing cell can often be shocked back to life if you
force enough current through it to cause the short to burn
away. Once that electroshock therapy is finished, the
battery can be recharged for normal operation.
Nicad Battery Reconditioning Construction
To assemble a low–cost "nicad nudger," start by
drilling holes in the plastic case and mounting the switch
and the neon lamp, as indicated on the parts layout. (Use
rubber cement to secure the lamp.) Then solder the components
together, being careful to observe the polarity of the
capacitors and the diode. Tie knots in the AC line cord and
the clip leads inside the case, so that the wires won't pull
on the components inside. This is particularly important with
the line cord: If the uninsulated leads were to come out of
the side of the case, you could get a life–threatening shock!
For safety's sake, please follow the directions carefully,
and use only a plastic case.
The Healing Battery Machine
The nicad resuscitator can be used to resurrect
batteries up to 22 volts in capacity. With the line cord
unplugged, connect the red and black clip leads,
respectively, to the positive and negative terminals of the
faulty battery. (You may need to use a specific type of
connector, such as a battery holder, to attach some
Insert the plug into an outlet and wait until the
READY lamp lights. This should take about 90 seconds. Now
press the RESTORE button. The READY light should go out. If
not, check your battery connections.
It may take several
cycles to completely "cure" the battery, so continue the
procedure until the battery accepts a full charge under
normal charging conditions. Be sure to allow sufficient time
for the READY light to come back on before you push the
RESTORE button again. When you're done, always unplug the AC
cord before disconnecting the battery leads, and always leave
the cord unplugged when the unit is not in use.
nicads can be restored by this method — even under optimum
conditions, there are limits to their lifespans — but most can.
In a few cases, the battery's capacity will only be partially
restored. But even then, some is better than none. And you
may find that many batteries will return for another half (or
more) of a lifetime.