At 07:10 AM 9/30/2003 +1000, Jon Jenkins wrote: >The situation with NiMH is quite complex >but the theory goes some thing like this: > >start: >charge pulse for 100-500ms at 2-4x Ah rating >monitor dv/dt for inflection >reverse charge for 10ms at 0.1 rate The data I have says 3-5C reverse. >1: dV/dt inflects >2: dT/dt > 10C/hr or |T| > ~50C (varies) OR maximum delta-T, or out of limits battery voltage. >3: total time x charge exceeds 1.5 x Ah rating > >jon > > >--On Monday, September 29, 2003 8:27 PM +0200 rene@DUBARON.COM wrote: > >>just some other notes on NiMH batteries. first, make sure it's the >>batteries getting hot, not the charger itself. >> >>secondly, make sure batteries can hold the charge. decharge them first >>(NiMH decharge until +-1V minimum, do not do full decharge like possible >>with NiCd!) >> >>also, NiMH batteries only have full capacity after 2 or 3 full >>charge/decharge cycles. the first time you use them and expect 2000mAh, >>you'll be dissappointed. but after using them several times, the capacity >>will increase dramatically. >> >>so, if you charge brand new batteries in an hour, you will probably >>destroy them. since overcharging is very bad for you batteries, and new >>batteries simply cannot hold the charge, so they will dissipate it as >>heat. >> >>so, the first 4-5 times, just charge them very slowly (say 9-10 hours or >>so), and decharge them. then after that, you can use the fast charge >>methods. this is probably mentioned in your chargers manual. >> >>rene. >> >>Op maandag, september 29. 2003 19:50:36 schreef Tim Hart >> : >>>The other day I read that charging NiMH in 60 minutes might harm the >>>batteries. My 1800 ma/h AA batteries do in fact get quite hot during the >>>charging. I leave the lid off just for cooling. The article >>>recommended 4 hour charging when you had the time and 60 or 90 minute >>>chargers when you didn't :) >>> >>>Anyway the other day I saw a charger from Energizer that claimed to work >>>in 30 minutes! That sounds like a ploy to destroy batteries and force >>>the consumer to buy more NiMH batteries or maybe even give up and go >>>back to disposables! A 2000 ma AA would be getting around 4 amps to >>>charge in 30 minutes....that seems quite excessive! >>> >>>I'm just a newbie here but I was wondering what you guys and gals had to >>>say!? >>> >>>Thanks, >>>Tim >>> >>>-- >>>http://www.piclist.com hint: PICList Posts must start with ONE topic: >>>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >> >>-- >>http://www.piclist.com hint: PICList Posts must start with ONE topic: >>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads