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

Robert Bruninga bruninga at usna.edu
Thu Feb 25 18:27:40 UTC 2016

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.


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.


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