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

[Tomas Härdin]

Linear has a whole bunch of useful ICs for these kinds of applications.
Probably Analog Devices too. Example: http://www.linear.com/product/LTC
3105. Their µModules look quite useful too

It's not entirely clear from your paper how your test rig works. The typical, simplest way of testing PV regulators is to use a constant-current source in parallel with a diode string

A good idea though, only turning the charger on if there's enough voltage. That way the rest of the system can work even if there isn't enough light yet to enable charging. It seems too many sats die to these kinds of problems

/Tomas, SA2TMS

On Thu, 2016-02-25 at 13:27 -0500, Robert Bruninga wrote:
> 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