[aprssig] Solar charging again

[Robert Bruninga]

>>> scott at opentrac.org 5/5/2005 6:18:46 PM >>>
> I'm interested in solar charging for small systems...
> The average power... can be kept to under 50 mW. 
> The tracker maybe 6 mA at 5 volts...  I figure a 
>6" by 6" or smaller panel should be able to do it
> but I'm not sure about the efficiency of small 
>charging circuits. 

You dont need any circuit.  Just hook the panel to the
battery through an isolation diode.  Reason is, you 
want every bit of current into charging and you cannot
possibly overcharge the battery with such a tiny panel.
(assuming you are Using AA cells)...  Also use NiCd's
instead on NIMH since they are less critical to 
chargning anomolies...

For AA nicads, the trickle charge rate is probably 50
to 100 mA for 500 or 1000 MAH cells.  So as long
as your solar panel cannot pput out more than
50 or 100 mA, then there is never any problem with
overcharging...

Bob