Bob,
Thanks for the advice. I have run a quick test this morning; and I think that Don’s educated guess is right. I still have the pack that I discharged yesterday; and I haven’t charged it yet. I peeled off the plastic “blister packing” and put it under load just long enough to measure the voltage on individual cells. Cell #1 was about .5V and diving, Cell #2 was 1.26, Cell #3 was about .3 and diving, Cell #4 was 1.26. So, it appears that I have two “duds” in this pack. Here is the kicker…I bought these packs new and they have never seen a charge rate higher than C/6…even that was just momentary during testing. This pack has been through two charge/discharge cycles and both charge cycles were conducted by C/10 slow charging. The problem is definitely not fast charging. My top three suspects are: 1. Slow charging too long? I let the pack charge at C/10 over the weekend in order to really equalize the cells. The pack never really heated up (I measured about a 6deg C temp rise). But maybe NiMH doesn’t like this kind of treatment. I know that Lead acid and NiCds love it. 2. Damage from initial discharge cycle? Maybe I let this pack discharge too deeply during the first discharge test and damaged the cells. 3. Maybe I just got a dud pack? After all, I just bought them from some “batteries-r-us” website. Chris Maxwell Nettest ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
