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 monitor dT/dt for rise monitor total charge x time goto start You drop to trickle charge when any of three events occur: 1: dV/dt inflects 2: dT/dt > 10C/hr or |T| > ~50C (varies) 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