I have a small sensor monitor system which uses Zigbee (Xbee 2.4 Ghz models= ) to send back various telemetry from my 5 acres of land. Thus far, the on= ly one I have actually built and installed is a swimming pool temperature m= onitor, but I plan on having that station do double (or triple) duty eventu= ally, and monitor things like air temp, wind speed and direction, solar rad= iation, etc. I have need of two or three locations to put these critters where it will d= o things that are "slow detection" type events: opening of a mailbox, dete= cting someone driving up the driveway, etc. Yes, I'm just that geeky. The pool sensor bundle consists of 4 DS18B20PAR+ temp sensors, a 3.3v Ardui= no "mini mega" with entirely too much I/O for what I need, and a Xbee. I'v= e got most things on the Arduino turned off, unused lines are configured as= inputs with pull-up resistors to keep them from floating, etc. I also sle= ep the Xbee other than perhaps 1 second out of each 60, when there is somet= hing to be transmitted. I don't currently power the DS sensors up only whe= n needed; they have a fixed resistor tied to Vcc for now, but I intend to i= nstead use an additional I/O line from the Arduino to supply power only whe= n needed. I also slow the clock down to the minimum, which and a timer tic= k happens once every 3.4 seconds or so, where it wakes up briefly, sets the= clock back to 8 Mhz, checks to see if we have something to do, and if not,= sets the clock down to minimum and sleeps again. Using the Vcc monitoring built into the Xbee, I have seen a 0.02 V drop in = 4 days, powered off two standard alkaline AA cells. =20 What I'd like to do is find a LiPo charger with 3.3 V DC output, a solar in= put, and as an option an external DC supply. As I live in Oklahoma, I thin= k the biggest problems are keeping the LiPo in the proper temperature range= , not a supply of sunlight. However, I'd obviously like to keep things plu= nking along all night. My ideal system would include: (1) 3.3 VDC output. (2) Solar input. (3) DC input, say from a USB or wall-wart. (4) A wide range of LiPo capacities. (5) The ability to intelligently use (2, 3, 4) together such that it will = take power from either (2) or (3), use the excess to charge (4), but will u= se combinations when (say) the sun is low but does provide SOME power, but = not enough. That is, it will only augment solar with the LiPo when needed,= otherwise it could run entirely off solar even if the LiPo is otherwise fu= ll. (6) Some logic-level indication about the power source, or if the LiPo is = being drained, charged, or is "idle." (7) A logic-level indication about the charge on the LiPo. I know, a long list of desires. Anyone know of such a beast, ideally one I can buy rather than build? Expl= oding LiPo does not smell good in the back yard. Thanks! --Michael --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .