How do I know what current to charge at? I've noticed that most chargers seem to talk about 4.2V. I'm a bit afraid that it won't be quite so easy to talk to the protection circuit. The battery pack has 4 pins. After looking at some of the protection circuits available, it seems like it shouldn't be too hard to construct one of my own. They only seem to protect against overvoltage and undervoltage. Is this all I need? Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams On Fri, 20 Aug 2004 21:23:27 -0700, William Chops Westfield wrote: > Probably one supervisor and one power mosfet. > > A benchtop (constant current, constant voltage) power supply does a > fine job of charging bare Li-ion cells. If your battery packs are > 'known good', it may be useful to leave the protection circuit inline; > it sounds like one of the simpler ones that just does the > current/voltage limits, rather than one of the ones you have to talk to > before you can use the battery... -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.