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Jeff

wrote:
OK

I have a twin engine houseboat and want to add an inverter and battery
bank. I've been working up the plan but have some questions I hope
could be answered here.

First the boat as configured:

Twin gas engine (350HP Crusader)
7.5Kw Kohler Generator
3 Batteries - 1 Group 27 dual purpose for each engine (also run house)
and 1 Group 24 for Genset
ProMariner Tournament 150 smart charger (15A 3 output distributed
charging)
3000w peak 1500W continous inverter

I'm looking at adding a remote battery bank (30' from engine room)
with (4) 6v 220Ah batteries for a total of 440Ah at 12v. My thought is
to use a Blue Sea 7600 ACR feeding the power through 4G cable from the
engine room to the remote battery bank. The ACR has a current limiting
feature which will allow me to get by with the smaller cable since the
connection is only needed for charging. I'm not married to this
approach and am open to alternate suggestions. The output of the
inverter will connect into 2 Blue Sea 8366 (3 position + off) rotary
AC switch which will then feed into the existing breaker panels.

Now for my questions:

Is there any way to connect this so I can get the alternator output
from both engines to the remote bank? It would be nice to be able to
have either or both engines charge this bank while underway.

Any ideas how to build a system that will vent my remote battery box
during charging but not run when it's not being charged? Something
that turns on a fan when either the charger or alternators are
charging and then shuts it off when they stop.

What's the best way to terminate the cables? I know enough not to
solder them on, but hammer-type crimpers seem like they would be
difficult to work with in tight spaces while plier-type crimp tools
are EXPENSIVE. I found some 4g ring terminals that use a set-screw
system to clamp the wire but am not sure how well they would work.

There's probably more to conside but that's what I have for now.

Marc
"Fat Tuesday"

I have a system that's similar: a catamaran with two engines, two
starter batteries, a house bank with 4 6-volt golf batteries, a large
Xantrax charger/inverter, and some solar panels. I also carry a small
Honda generator so I can charge without running the engines.

Some observations on your proposed system:

Use larger cable for the long run to the new house bank. This will
allow "full charging" (about 95 Amps) without a large Voltage drop.
Your 4 gauge of 30 feet (actually 60 feet round trip) will have a 10%
drop with only 50-60 Amps - not good! The alternator output will be
have to be jacked up to 16 Volts to get 14.4 at the bank, and 10% of the
energy produced will be continuously lost in heat which is trying to
melt your cable!

The ACR you mention is only good for 60 Amps continuous. If you
discharge the 440Ah bank to 50%, it would take 3 hours of charging (or
more) to get it back even to 85%. If you have to do this daily (you
never mentioned your energy consumption) it will get old very quickly.

All charge sources can simply be connected together and fed to the house
bank, but it is possible that the two alternators will confuse each
other a bit. I have a high output alternator on one engine, and that
dominates the other. However, there really isn't a problem other than
you can't just add to output of all sources and assume that's what the
charge rate is.

You want to disconnect the starting batteries during discharge; a
combiner will do that but I use an "EchoCharge" that is like a small
charger that turns on whenever the house bank get charged, but ensures
that the starter bank gets treated properly with its own charging regime.

Whatever system you use for combining, make sure you map out everything
in advance. My stock alternator was tied to the starter and hence the
starting battery. When I put in the "smart" regulator, it was sensing
the starter battery, but charging the house bank. Every now and then the
Voltage started running up and cooking the batteries. The solution was
to add an extra cable run so the starter bats are kept separate until
they are used.

The generator feeds the big charger, but being a tad undersized I can on
get about 75 Amps into the bank. Plus its noisy, but it does save wear
on the diesels and is a great backup.

I've made up cables with the "hammer method" and the "see-saw" jig.
Works just fine.

One more thing: Larry will probably claim that its physically impossible
to charge your 440 Ah bank at more than 25 Amps. I have the same bank,
and charge it almost every day during the summer at 80-95 Amps. The
first bank of Trojans lasted 6 years, the second is now going on 4
years. I'm sure that the New England winters are far worse for them
than the summer usage.