[volt-nuts] Fluke 735C - Information Needed

[Charles Steinmetz]

Joe wrote:

>I found 1.2 V 2.5 AH 1/2 D cells for $5.50 ea. On the internet.  I would
>like to find a cheaper source since I need 20 of them, enough for two packs,
>one pack on each side of the Battery PCB.

Available NiCds exhibit a huge range of quality.  Also, series 
strings last much better if the cells are matched for capacity and 
leakage.  The best results I've ever had with NiCds are with packs 
made up by SR Batteries (www.srbatteries.com/).  He carries extremely 
high quality cells and matches them for series packs.  I doubt his 
prices are the lowest, but you will not find better, longer-lasting 
packs than his.  Usual disclaimers.

Finally, you do NOT want to solder to NiCD cells -- welded tabs 
only.  I did a study for a client some years ago, which showed that 
soldering, even very quickly and carefully, had disastrous effects on 
NiCd battery life.

>I wonder what would be better, SLA or NiCd's?  The NiCd's had 'spewed' and
>corroded the PCB a bit but I have that cleaned up.  I have seen SLA's (in
>UPS's) 'shrivel' and get very hot as they die.

The charging protocols are very different, so you are committed to 
what was there before unless you re-engineer the charging 
system.  Since even a repair to the 732A charging circuit, which is 
then adjusted to specification according to the manual, throws the 
unit out of calibration, changing the battery type and re-engineering 
a charger could have unfortunate effects on the standard's 
stability.  For practical purposes, you are probably committed to the 
NiCds that were there unless you are willing to install SLAs and 
clone the 732A charging circuit.

Best regards,

Charles