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Jeff

wrote:
Isolators are a waste of energy, combiners mean the starter bank is
overcharged.

Somewhat agreed, depends on the charge source & duration. A combiner is
nice & simple, low voltage drop (more efficient). It doesn't
necessarily mean that one or the other bank is going to be overcharged
though.

Not necessarily, of course. But in my case, my starting batteries (I
have twin engines) are never discharged more than 1 or 2%. They are
AGM, so they don't self-discharge much, and my Yanmars always fire
within 2 seconds. They are essentially 100% charged, 100% of the
time. My house bank, on the other hand, often runs between 80% and
50% discharged on a daily basis. It is charged up with a 100 Amp
Alternator with a fairly aggressive charge profile. Other times it is
charged with a 100 Amp shore power charger (sometimes through a small
genset) that is almost as aggressive.

In other words, the charge profile the house bank sees is exactly
wrong for the starting batteries, and that is why I don't like using a
combiner. I have a combiner, but mainly I use the EchoCharge instead.

Jeff wrote:
These are two separate issues. The EchoCharge can tie in on the hot
side of the house bank, and thus is connected to all of the charge
sources. Its output goes to the starter bat as its only charge
source. This ensures that the starter bat get its appropriate
(normally trickle) charge even if the house bank is receiving a voltage.

Your alternator has an echo charger?

No, I have a standalone EchoCharger attached to all of the charge
sources (two alternators, solar panels, shore charger) and the house
bank. The output of the EchoCharger is the combiner which feeds the
two starting batteries.

A combiner is generally used only on the alternator output, which is a
shourt duration charge source and not likely to seriously overcharge
the battery ...unless the voltage regulator is FU or the battery(s) are
hot. A better charge regulator, external to the alternator (with temp
compensation) is a very good upgrade.

What if the alternator is really being used to charge a seriously
discharged house bank? The question here is the meaning of "short
duration" - for me that's an hour or more every day while cruising.

I have only seen echo chargers on 120V chargers; a better set-up
available now is completely seperate regulation available on seperate
legs.

This is true if you're shore power based, not if you live on the hook.
The EchoChargers that are built into Xantrex chargers were first
developed as standalone devices, and although they are a bit pricier
than combiners, they do the job properly.

The other issue is that most engines have a strap directly between the
alternator and the solenoid, and on to the battery switch. In my
setup (actually refer to Nigel Calder's book for this) you want the
alternator to feed the house bank, and the solenoid fed by the starter
battery. Thus, the strap must be removed.

The way that most older boats are set up, the alternator/solenoid
strap is at the "common" of the Big Red A/B switch. Current thinking
is that the starter and the house system should be separate circuits.

Well, they should have been all along, but it's cheap and simple and it
works for weekending (most of the time).

True, but most of the weekender's have a story about the time they
forgot to flip the switch ... I have a few.