Eric wrote:
NiMH cells seem to work in the 731b so I'd prefer to use them over NiCd because of the higher capacity and lower toxicity of potential leaks. Is there a downside to doing this?
In my experience, good NiCDs are preferable to NiMHs. Good NiCds have substantially lower self-leakage than NiMHs (this is true even of the "NEW!! Low-discharge!!" NiMHs). NiCds also don't degrade nearly as fast if they are left too long on trickle charge. Both of these features translate directly into increased life for the NiCds. NiCds are also quieter, and capable of larger current drains, due to their lower internal (series) resistance (high current is not really an issue in your application).
Consumer-type NiCds may suffer from the problem PHK noted (poor quality due to low production volumes), but there are still many industrial and military applications that specify NiCDs for some or all of the reasons given above. Excellent NiCds are readily available -- just look for aerospace-grade parts rather than consumer batteries.
Many built-in charging circuits are crude and leave the batteries on a trickle current that is really too high, particularly given the temperatures inside electronic instruments. So whichever batteries you choose, plan on redesigning the charging circuit.
That brings up the possibility of using either LiFePO4 or SLA (sealed lead-acid) batteries -- if you have to redesign the charging circuit anyway, you can just as easily design it for LiFePO4 or SLA.
I have not evaluated the 731B power supply in particular, but LiFePO4 would be my presumptive choice unless I encountered an insurmountable obstacle.
Best regards, Charles _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
