The most modern alternative is the "Battery Combiner". The connections
in this device are actual relays (0.0 V voltage drop). They leave the
batteries isolated until they see 14 (approx - value adjustable) on one
of the banks, indicating it is being supplied by a charger. In this
case, the relay closes, combining the batteries for joint charging from
the single source. When the charging voltage disappears, the relay opens
again, isolating the batteries.

bob

derbyrm wrote:
I'm looking forward to others' comments, but first:

The only diodes available today are "solid state" devices. Forward voltage
drop will typically be 0.5 to 0.7 volts unless it's a Schottky type. Could
be compensated for by sensing on the battery side or by telling the
controller there's an isolator.

FETs (Field Effect Transistors) are "solid state" devices. The voltage drop
is a function of current, figure 10 to 200 ohms on-resistance.

Huh?

Roger

http://home.insightbb.com/~derbyrm

"Steve Lortie" wrote in message
...

I'm starting to give some thought to my power source on the house boat I
am
refitting. I am leaning towards using isolators to seperate the battery
banks. I would like some experienced feedback on what type of isolator to
use; diode, FET or solid state? All I know at this point is that the drop
across the diode type can play havoc with the battery life because of the
voltage drop never allowing a full charge (?). The other two kinds I have
not been able to get anything except that they have a much smaller v drop
(FET) or none (solid state). And that is from sales materials. Will using
isolators allow me to forgo the 12Both switch and just use an in line
on/off
switch?

May seem like a dumb question but how do I know what size of charger I
will
need or does size (amps) matter other than how quick it will charge the
batteries. I plan on having two start and two house batteries.

How important/neccessary is it to have a galvanic isolator on the AC side?

THX