[aprssig] Charge controllers

[Jim Lux]

I'm using an EchoCharger to charge a deepcycle battery from the car
electrical system, which is a similar application.  You want to charge the
battery, but only when the engine is running, and you don't want to
discharge the deep cycle back into the car's electrical system, AND, you
want a "real" battery charger with all the steps and tiers to improve
battery life.  They run around $100.

There are a lot of this sort of thing for RVs, as well.

But why use the Astron at all.  I suspect you could buy a good battery
charger, designed for this sort of application, for less than price of a
Astron and a charge controller together.  It's not an unusual application to
want to float charge a big battery while also supplying the load current.
The "real deal" usually has a separate wire to the battery and to the load,
so that it can distinguish between the two.  If you don't worry about last
percent of efficiency, etc., you could probably also cobble up something
with a couple Schottky diodes to OR the output of the Astron and the
battery, and then get an inexpensive float charger for the battery. Set the
Astron voltage slightly higher than the battery charge voltage, and all the
current will be drawn from the Astron, because the battery's diode will be
reverse biased.