View Full Version : Rechargeable battery circuit

04-11-2007, 04:08 AM
I want to take Basic Stamp to the next level by making it potable with rechargeable battery. Here are the requirements:
-ииииииии When wall adapter is not plug in, the circuit is running of 9V Lithium (Li/Mn2) rechargeable battery.
-ииииииии When wall adapter is plug in, the circuit is using power from wall adapter. At the same time, it charges the battery and automatically shut of the charging circuit when the battery is fully charged.
This is similar to laptop battery system. Any idea of what IC should I use? Circuit diagram? Application note? Any material that I can read to make this happen?

Mike Green
04-11-2007, 05:56 AM
Lithium batteries are very dangerous to charge without a specific charger circuit. I would very much recommend using Nickel Metal Hydride (NiMH) cells, probably 6 AA cells for an output voltage of 7.2V with a capacity of 2.3-2.5 AH. Have a look at the MAX712/713 here: datasheets.maxim-ic.com/en/ds/MAX712-MAX713.pdf (http://datasheets.maxim-ic.com/en/ds/MAX712-MAX713.pdf) for a fast charger. You'd need a diode in series with the battery output and the wall adapter so whichever supplies the higher voltage will supply the device.