"Tom Francis - SWSports" wrote in
message ...
I've been trying to get some specs on this unit - seems like a really
good way to charge trolling motor batteries on long runs spot-to-spot
on a large lake or on runs from spot-to-spot inshore.

http://tinyurl.com/564jl4

I can't seem to find anything that gives the specifics on how this
works. I'm speculating here, but I would assume that it works to
charge the trolling motor batteries once the main battery system is
charged. I'm guessing that is must work on an interrupted basis -
meaning that once the starter battery is charged, it switches to
charging the 24 volt system.

Here's the thing - how?

If I were designing this, I would make it so the engine would have to
be running above idle and the charger producing more than the nominal
13.6 volts needed to run the engine. That would mean that each battery
in the 24 volt system would need to be charged a little at a time -
like say a minute for one, a minute for two - back and forth until the
batteries were charged.

That's the way I would do it, but there are other ways. I just can't
find out how it works.

Anybody have experience with these things?

Except for the fact that it connects directly to the alternator, it doesn't
sound any different in operation than a typical multi-output charger. I
assume by a "24" volt system, you are referring to two, 12 volt batteries.

Multiple output chargers (120vac powered) are used all the time, in both old
fashioned ferro-resonant types and the newer "smart charger" types. The
Navigator had both. It had a three output charger for the engine(s) and
house (also used for the genset) plus a 2 output smart charger for the two
smaller, thruster batteries.

The outputs were completely independent of each other, just like having a
dedicated charger for each battery.

You may be thinking of a battery isolator/charge controller. These
typically operate by comparing the voltage of each battery and, if the
difference exceeds a certain amount, it directs the charge voltage/current
to the lesser of the two. I think.

Eisboch