On 19 Dec 2001 at 20:38, Doug Franklin wrote: > On Wed, 19 Dec 2001 12:10:00 -0500, Otis Wright, Jr. wrote: > > > Any one know out there happen to have info on the relative "short > > circuit" characteristics of NiCd, NiMH, Alkaline, Lithium etc. cells? > > A six-cell pack of 1400, 1600, or 2000 mAh Sub-C NiCD (Sanyo or > Panasonic) cells is reputed to deliver 100A or more of dead-short > current for a _very_ short time. Within five to ten seconds, the cells > overheat to the point they can give you a 2nd degree burn and they > violently start venting gas (don't know what type of gas). [Sub-C cells > are slightly smaller than a "C" size alkaline battery.] I've seen this > happen several times in the 1:10 scale electric R/C cars. > > In a controlled test several years ago, an acquaintance measured a > specific six-Sub-C 1600 mAh pack dead shorting a bit over 100A for less > than five seconds. The current delivered dropped off to zero over the > next thirty or so seconds as the internal structure self-destructed > from the heat and and the chemical system was depleted by the venting.
:-) Keen, I just checked the specs for the 1600mAh AA NiMH cells that I use in all my gear, the shirt circuit current is 7.75A for 2 seconds max, the cells internal resistance when fully charged is 25 mOhm. see: http://users.skynet.be/bs137713/DATASHEET/pdf/VH1600AA.PDF AFAIK NiMH cells have a higher energy density than NiCd cells but NiCd have a far higher short circuit current in most cases. I believe that some aircraft use NiCd batteries for starting? In school we used to use charged AA NiCd cells to heat up the pocket clips on old Parker ball point pens before sending across the room via air <vbg> Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications.html - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
