[amsat-bb] Charging Cubesat 7v NiCds from 4.8v solar panels

[Robert Bruninga]

For charging 7v NiCd from 4.8v:



We came up with a simple circuit to use the cheap DC/DC boost regulators to
boost 4.8v solar panels to 7 volts for our NiCd charging.



http://aprs.org/psat/Cubesat-solar-boost-charger-bob-a.doc



You cannot just use the DC/DC boost regulator directly because it has a
peak-starting-current which cannot be met with a solar panel.  So we added
a transistor load switch to hold off the load until after the regulator was
started…  Works like a champ at near 80% efficiency.



I’m sure there are lots of circuits and parts, but this little circuit more
or less worked the first time, so we are going with it.



Bob, WB4APR