SAFT NiCd "block" battery high cell voltage

 Any experts here on large nicads?

I just picked up 45 used SAFT SBM43-2 NiCd "block" batteries. Each battery
appears to be 2- 43 AH cells with a jumper bar attached between the two cells
putting them in series electrically. Each battery measures 3.4-3.62 volts, which
seems on the high side for 2 cells voltage. According to the technical manual,
they should be charged at 1.7V/cell max, which would produce 3.4V / battery.
Could the higher voltage be indicative of batteries near their life end? Or were
they last charged at too high of a voltage? Or??

Cost - 20 mile drive each way.

http://www.saftbatteries.com//130-Catalogue/PDF/tm_bb_en.pdf
http://www.saftbatteries.com//130-Catalogue/PDF/com-data_bb_en.pdf  

 

Don't know about expert but somewhat experienced.

which

were

Wet NiCads are almost impossible to kill and their lives are measured in
half-centuries.  My oldest wet battery is a Korean-war-vintage 28 volt aircraft
starter battery.  Still at full rated capacity.  I've had to change the
electrolyte
(KOH) a couple of times, as CO2 from the air slowly neutralizes it, but other
than
that and an occasional watering, nothing else done.

You can't hurt a wet NiCad with moderate over-charging or discharging. In fact,
the
usual storage configuration for wet cells is fully discharged and shorted.  All
they
do on over-charge is get warm and use more water.  The plates will NOT lose
active
material like PbAs do.  Moderate over-charge of a series string is necessary for
proper equalization.  I suggest putting some cells through charge/discharge
cycles
and see what you get.

I think that SAFT adds something to their electrolyte that raises the voltage a
tiny
bit.  That may be the root of what you're seeing.  You might drop SAFT a note and
ask.  SAFT says not to change the electrolyte but that may be necessary if these
cells were not stored properly. Again, they can tell you for sure.

I'm green with envy :-)

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
Better remain silent and be thought a fool than to cite Wikipedia and remove all
doubt.

 I maintained a few ni-cad banks years ago. 1.22, 1.33 & 1.44 volts per
cell rings a bell. I think that was nominal, float and equalize
voltages.

You really need a constant current charger as the voltage is a really
nonlinear curve to their charge.
Things I remember
- we used them in outside stations as their cold curve was much better
- they had small capacity per size compared to lead/acid units
- we got rid of them all
- chargers like to "hunt" or oscillate if you try to charge them with
a voltage unit. Touching feedback damping was the key to prevent it.
Most chargers these days have never heard of this adjustment

Have fun.

 

Thank you both for the info.

Bob F