Randy, Most lithium cells (probably all, but I do not know that for a fact) do not like float charging. When overcharged, they may explode in a nasty way. Also you do not want to charge multiple cells in series without a balancing circuit. If you plan on using lithium batteries, make sure you use a charging circuit specifically designed for the chemistry you are using.
Didier KO4BB Randy Evans <[email protected]> wrote: >John, > >I looked at the LTC2057 but it doesn't go down to 3V operation (4.75 V >min) and I want to power the Fluke 845 with 3V lithiums. In addition, >the LTC2054 has a lower input bias current (1 pA at 25 C). I wanted >the lower bias current since I want to use the circuit to upgrade an >HP-419A also, and the 419A measures current down to a FS range of 30 >pA. The LTC2057 bias current is spec'd at 30 pA typ, which would make >it useless for measuring the lower current ranges of the 419A. > >Regarding the isolation amp, I did find a good, relatively low cost amp >(TI ISO124) but it only works down to +/-4.5VDC, which means it is not >compatible with 3V lithium cells. I would have to use 4 lithium cells >instead of 2. I'm still looking for a good isolation amplifier that >will work on +/- 2 VDC but I'm getting pessimistic about finding one. > I might have to just bite the bullet and use +/-6VDC power supplies. > >Randy >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there. -- Sent from my Nexus 7 tablet. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
