We're talking 3AH cells being charged at 0.45A - that's a rate of only 0.15C. I doubt a standard 'dv/dt' type peak detection would work at that low a rate because 'dt' becomes large which makes the dv/dt very small. I'm not sure what algorithms the modern digital chargers use, but I wouldn't trust any form of peak detection at that low a charge rate. The good side is that the batteries shouldn't be damaged by overcharging at that rate. If the charger automatically limited itself to 0.45A then I suspect the cells aren't too healthy (very high internal resistance). If you limited the current manually then either manually stop the charge at Red's suggested 140% capacity, or try a higher charge rate where the peak detection has a better chance of working - but keep an eye on it as overcharge at higher rates can damage batteries. Ciao - Chris ****** Chris Kaiser (mailto:[EMAIL PROTECTED]) Auckland, NEW ZEALAND http://rcmodels.co.nz/clubs/asfcnz > -----Original Message----- > From: Red Scholefield [mailto:[EMAIL PROTECTED]] > Sent: Sunday, 23 September 2001 21:52 > To: [EMAIL PROTECTED] > Subject: [RCSE] Battery Charging question > > > This is typical for some "surplus" cells. The peak is missed, > particularly > with Ni-MH cells. If you input 140% of the rated capacity you > know the pack > is fully charged. I would not recommend using the automatic mode > for Ni-MH, > Use the manual mode where you can set the peak resolution to the finer > setting. > > Good Luck. > > Red Scholefield AMA 951 IMAA 18939 District V > > Date: Sat, 22 Sep 2001 17:12:30 -0700 > From: "Ed Berris" <[EMAIL PROTECTED]> > Subject: [RCSE] Battery charging question > > I built a four cell pack using some surplus 3000mah NMH cells. I used my > Robbe Infinity II charger in the automatic mode to charge this pack. The > charger showed that I had put 5500Mah into the cells after 13 hours of > charging at 0.45A. > > The question is how is it possible to pump 5500Mah into 3000Mah cells? As > you would expect, the pack was warm (not anywhere near hot) when I removed > them from my charger. The peak detector had not kicked off when I finally > decided to remove them from charge. How do I know if I got a > full charge if > the peak detect circuit did not detect a full charge? > > Inquiring minds want to know, > Ed > > > > > RCSE-List facilities provided by Model Airplane News. Send > "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
