As I recall, a solar cell acts like a voltage limited current source. If the voltage limit out of the panel is the same as the "float voltage" of the cell, nothing is needed (other than a diode to prevent solar panel leakage from draining the battery in the dark... and then up the solar panel's voltage a little to deal with the diode drop). If the solar panel voltage limit is too high, a shunt regulator across it will bring it down to what's needed. Harold On Thu, 28 Feb 2002 14:02:15 +0100 marco genovesi writes: > Alan, I have measured 40ma current with the tester probes between the > solar > cell and the battery pack, but the batteries were not full charge: > however > I will execute the test suggested and using the diode. > > Thanks > Marco > > > > ----- Original Message ----- > From: "Alan B. Pearce" > To: > Sent: 28 febbraio, 2002 12.46 > Subject: Re: [EE]: mini solar charging system > > > > >tested with a small (1" x 3") solar cell from a toy and I have > > >measured about 40 milliamp. out in direct sunlight. > > > > Is this just by putting a current meter on the solar cell, so you > are > > measuring short circuit current? The current will then be less > when > charging > > a battery. > > > > See what the actual current is when using a resistor as a load, > such that > > the voltage across the resistor matches the battery voltage. You > may need > to > > include a low voltage drop diode in the circuit as well. > > > > -- > > http://www.piclist.com hint: The PICList is archived three > different > > ways. See http://www.piclist.com/#archives for details. > > > > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.