Post by thread:[EE]: Help with battery choice

Lithium cells? Two in series will get you 6V, and they have huge power compared to their size. Cost might be a factor, not sure how cheap you can get them. TTYL heh. In case no one noticed, there has been a recent "price war" in the popular CR123A (1300mAH) sized lithium battery, because (?) of their common use in certain "upscale" flashlights. From sites like http://www.surefire.com, you can get them for $15 for a 12-pack (that compares to about $8 EACH for duracells at the local camera store...) I saw at least one spec on the net for CR2032 sized lithium coin cells that claimed they were good for a maximum drain of up to 4mA, but I can't find "supporting" documentation from any of the big-name manufacturers. BillW -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

\ > > heh. In case no one noticed, there has been a recent "price > war" in the popular CR123A (1300mAH) sized lithium battery, > because (?) of their common use in certain "upscale" > flashlights. From sites like http://www.surefire.com, you can get > them for $15 for a 12-pack (that compares to about $8 EACH > for duracells at the local camera store...) > > I saw at least one spec on the net for CR2032 sized lithium > coin cells that claimed they were good for a maximum drain of > up to 4mA, but I can't find "supporting" documentation from > any of the big-name manufacturers. > > BillW > Awesome! Thank you! Thank you! Here is says that the nominal current it 20 mA continuous: http://rocky.digikey.com/WebLib/Panasonic/Web%20data/CR2,%20CR123A.pdf What kind of battery holder would you use for these? It seems like an odd size. Alex -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

http://rocky.digikey.com/WebLib/Panasonic/Web%20data/CR2,%20CR123A.pdf What kind of battery holder would you use for these? It seems like an odd size. Actually, it's a pretty standard size for memory backup power and such. I've retrieved such batteries from token ring hubs and such, where they appear to last ... longer than token ring did. (I think they only got use to occasionally switch the state of some latching relays, so this isn't really surprising.) "Memory Protection Devices" once sent me some nice samples, so I'll recomend them here: http://www.batteryholders.com (some "web designer" got loose at their site, though. I had problems from my mac with both netscape and explorer.) There may be two varieties of these cells, one designed for memory backups and such, and the other for more consumer oriented high-drain applications. The duracell website has a data sheet with continuous discharge curves at currents up to 1A. (as well as the info I recently alluded to about how many 1.8A, 3 second pulses you can get if they're 7 seconds apart, and such.) BillW -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Personally, I would try the 2* cr2032 lithium coin cells and see how it works. It's not like you'd be the only one "violating" specs on these, and it's not even clear that you're doing that. You're just operating outside the region that is well-documented. If you need 50 hours and tests show you getting 52 hours, I'd worry. But if you end up getting 60 hours or more I'd think you'd be pretty safe. The cr2032 battery is another size that varies quite wildly in price. "cheap imports" regularly sell for about $0.30 on ebay, rather than the $2 each you pay at radio shack. BillW -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

>Awesome! Thank you! Thank you! > >Here is says that the nominal current it 20 mA continuous: > >http://rocky.digikey.com/WebLib/Panasonic/Web%20data/CR2,%20CR123A.pdf > >What kind of battery holder would you use for these? It seems like an >odd size. A disposable camera perhaps? Try your local 1 hour processing shop for any number of free samples which they will be only too happy to give you after they take the original customers film out. May even be a source of zero cost batteries - especially if there is a flash unit in the camera. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics