Ni-Cad Rejuvinator

[g_no]

I have an older VHS camcorder and the battery will not re-charge. I
know that there are rejuvinators on the market for ni-cad batteries but
they are only for standard sizes (AA, C, D, etc.). Does anyone have a
circuit I can use to rejuvinate my 12vdc camcorder battery.
Thanks!

 

[Pooh Bear]

I
know that there are rejuvinators on the market for ni-cad batteries

There are ?

Graham

 

[Mook Johnson]

Google it

I believe you can pulse each cell with a high current pulse (charged up
cap?) to burn away tiny dendrites that form fron low current use.

Try "zapping NICADs" and you should get something

 

[Mark]

yes, you have to open the "battery" to get to the connection to each of
the ten? "cells" inside...

I rejuv cells by connecting them to a 12 V 10Amp supply for a few
seconds.... they draw lots of current and clear out whatever is
shorting them inside... then charge as normal...

they work again , but never as well as orignally...

Mark

 

[ehsjr]

I have an older VHS camcorder and the battery will not re-charge. I
know that there are rejuvinators on the market for ni-cad batteries but
they are only for standard sizes (AA, C, D, etc.). Does anyone have a
circuit I can use to rejuvinate my 12vdc camcorder battery.
Thanks!

Something like this:

+V ---[R]---+ +--------+
| | |
| | |
o o |
SW \ [NICAD] *cell*, not pack
o |
| |
[C] |
| |
Gnd -----------+-----------+

Make C as big as you can, size R to limit inrush.
Transfer the switch to discharge the cap into the
cell.

I experimented with this a whole bunch of years
ago. As I *dimly* recall, I didn't get better results
by increasing C beyond 36,000 uF, nor did I see
any benefit going above about 24 V. However, those
numbers might as well be pulled from a hat. The one
number I do remember was a little better than 30 %
"success". The problem was, that the success was
very short lived. I was able to rejuvinate the
shorted cells, but they would re-short in a couple
of days. I ended up abandoning the thing as useless,
and found a much better technique: buy new cells.

Ed

 

[Joseph2k]

Google it

I believe you can pulse each cell with a high current pulse (charged up
cap?) to burn away tiny dendrites that form fron low current use.

Try "zapping NICADs" and you should get something

That is only step 1. Next you deep cycle it a few times, paying attention
to not overheat them. Finally charge them up slowly and leave on trickle
for 3 hours.

 

[g_no]

Definitely! They are usually for specific types of batteries (AA, C,
etc.). I need a circuit for more general use.

g_no

 

[g_no]

Tried that with no success, thanks