I use 3 alternators on 1 system, have had no trouble.
2 80A units are on my auxiliary engine, and are controlled by 1 regulator.
the other is on the propulsion engine and has it's own regulator. [
http://www.amsterdamhouseboats.com/v..._regulator.htm ]
I've found that with separate regulators, 1 unit will do all the work until
it starts getting hot, then it's protection circuitry starts tapering the
output and the second alternator takes some load. this leads to unnecessary
belt wear on the first alternator, as well as inefficiency. when they share
1 regulator, output, belt load, and heat are evenly split [I measured the
outputs].
if 1 huge machine fits your engine and your budget, go for it; but 2
separate units working together run fine, too.
regards, Mark Holden

"Steve Lusardi" wrote in message
...
Do so at your own risk. Yes it will work as long as all components are
functional. If there is a fault, it will damage both systems. Ask yourself
why anyone would wish to combine alternators on the same battery bank at
the
same time. It is self defeating. Each alternator should have the ability
to
charge any of the battery banks and any battery bank should be able to
power
any load and all options will be covered without risk.
Steve
"Larry W4CSC" wrote in message
...
(BOEING377) wrote in
:

hello all
is it possible to link 2 or more car alternators driven from the same
engine to a single battery
thankyou David


Yes, it works fine, no special hookup needed other than trying to get
the voltage regulator settings as closely matched as possible if you
want both alts to contribute their fair share of charging current.
Many fishing boats use this even without a perfect voltage match so
that if one alt fails, the other is online and you can keep fishing.


Lionheart has two alternators on her Perkins 4-108 diesel. If I put our
engine battery switch in "Both", the effect is that the 80A starting
battery alternator is parallelled with the 170A house battery
alternator.
No special tweaking of fixed regulators was done.

If some of the batteries are low, such as discharged house batteries,
both
alternators pull like hell at god-awful currents until the voltage on
the
two 700AH house battery banks comes up. Then, having the lowest voltage
set regulator, the 80A simply shuts down when its voltage regulator set
is
reached, while the 170A pulls whatever it pulls as the battery voltage
comes up.

It's an old wives tale you can't connect them in parallel. As someone
else
posted, commercial boats do it all the time.....but, of course, they
don't
have that expert help from the boater working at West Marine or the
Yacht
Club Bar....(c; All yachties need to ride, underway, in the engine room
of
a shrimp boat or commercial fishing vessel. It would give them all a
touch
of reality....

Larry