Ken, I agree with John's diagnosis of a shorted cell. If it's not damaged too badly, a method I use is to "blow" the shorts out of the failed cell. I'll charge a large capacitor to a fairly high voltage (12V) and apply it across the shorted cell (not across the battery). Zap it a few times as required to clear the short. I've had cells last for years after this and sometimes there are so many dendrites that I just couldn't clear the short.
Note that the shorted cell failure is the most common NiCd failure mode. The oft-quoted "memory problem" is a rarity and requires just the right conditions to induce (not likely in consumer equipment). I've seen countless batteries that supposedly had acquired a "memory" that actually just had a shorted cell. Regards, Stu Benner www.emcwizard.com From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Thursday, October 05, 2006 11:33 AM To: [email protected] Subject: Re: end-of-life battery effects In message <c14a8bf1.452f5%[email protected]>, dated Thu, 5 Oct 2006, Ken Javor <[email protected]> writes >Today the case was hot to the touch, and I disconnected it. What is >happening to the battery? It is almost certainly an NiCd that has 'whiskered' and shorted out some cells, so that it is now drawing excessive 'charging' current. If you continue, the charger will burn up. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Swine wave - a waveform whose spectrum is exceptionally difficult to calculate. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - 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/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
