[aprssig] Re: more solar charging

Jim Lux jimlux at earthlink.net
Fri May 6 13:39:25 EDT 2005

Dale wrote:
 > That is a very complicated way do do things ,when solar charge controllers
 > are available
 > for less than $30.00 that work. On some small systems are not needed.
 > It reads like a solution to a non existent problem.

As Scott mentioned, the run of the mill charge controllers might not work. 
The inexpensive ones are designed to charge lead acid batteries from a 
solar panel voltage > battery voltage, and are usually some form of "shunt 
regulator".  NiMH is a bit trickier to charge (if you don't want it to 
explode AND to actually get the improved performance out of them).

It's also possible that the $30 charger actually has all the right circuits 
in it. After all, those Maxim parts aren't particularly expensive, 
especially if bought in 10,000 quantities.

Of course, it's all a tradeoff.. Maybe oversizing the solar panel and 
battery and using a cheap unsophisticated charger is the best "system" 
solution.  It's not like you're trying to send the system to Mars on a 
rocket and need to eke out every last milliJoule, gram, and possible 
failure mode.  So what if your battery has half the rated life, as long as 
that's "good enough" for your application.

Jim, W6RMK

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