we were all waiting for someone who knew what they were talking about to jump in. But since no one did I guess I'll reply :-) I did this with NiHM cells and it worked really well, I had nothing betwee= n the solar cell and the batteries except a diode and then I had an LED drive= r chip on the other side. The devices were LED lamps behind a small stained glass panel in the windowsill and I had a transistor on the cel so that duriing the day when the thing was charging the LEDs would stay off, but at night when the cell went to 0v the led drive would come on and light up the panel. I've been running these things for years. About every 3 or 4 years I throw a new set of batteries in. I don't know anything about LiPO but if you don't mind going down-tech NiMH are incredibly resilient to this kind of charging. DougM On Fri, Jun 3, 2011 at 11:15 AM, V G wrote: > Nobody? Post went through? > > On Wed, Jun 1, 2011 at 4:45 PM, V G wrote: > > > Okay, so would this work? > > > > My idea is to use one of these solar cells ( > > http://futurlec.com/Solar_Cell.shtml), probably the 6 or 9 volt, plug i= t > > into a small buck switching regulator and charge a 100-200mAh Li polyme= r > > cell. > > > > Reasonable? > > > > The idea behind this is to be able to leave the device (guitar tuner) > lying > > around anywhere and charging it from ambient light. At most, it would g= et > > used for a few minutes, once a day, max. So not much energy drained fro= m > the > > battery. I'd like to keep the battery floating at 60-70% charge to get > the > > most shelf life (years) out of it. > > > > For example, I like the 6V 60mA cell on that page. Good size, reasonabl= e > > price. The question is, how much voltage and current can I get out of i= t > > under ambient light conditions? For example, a room with the lights on > and > > possibly some daylight (not direct sunlight) shining on it. > > > > Any other ideas? > > > > I want to make it as easy and thoughtless as possible to charge the > device. > > Another option may be an inductive ("wireless power") charging mechanis= m > > where you just put it down on a charging pad and it charges through > > induction. > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .