On Fri, 17 Jan 2014 07:05:29 +1300, "Bert van den Berg"
wrote:

Hi All,

I originally considered running heavy cables from the house bank to the
windlass but there was no cost or weight savings. Our thoughts were that
having a separate 110 amp hour windlass battery gave us some redundancy
should we ever screw up and deplete the main 660 amp-hour house bank (which
is also used to start the engine). I've done this once and believe me, the
trouble of lugging the windlass battery from the forepeak to the engine
compartment taught me to be more careful.

The Voltage Sensitive Relay sold by several shops are intended to direct all
the alternator charge current to a start battery until the start battery
reaches a certain voltage then it parallels the house bank to the start
battery and continues to charge both banks. My situation is slightly
different. I also have two 90 watts solar panels with a solar charge
regulator connected to the house bank and would like the windlass battery to
get some charge whenever the house bank voltage exceeds the windlass battery
voltage and disconnect the two when the house bank voltage is less than the
windlass battery voltage.

Still, it's good to hear from others how they handle this situation.

Cheers,

Bert

I had a look at the old West Marine catalog I mentioned and the
"battery combiner" connects another battery to the main battery when
battery voltage reaches 13.3 VDC and disconnects it when the voltage
drops to below that figure.

An alternate is to connect using a diode which is essentially an
electronic one way valve so the remote battery can receive a charge
bit not provide voltage back to the parent battery but that evolves a
slight voltage drop through the diode.
--
Cheers,

Bruce in Bangkok