twin alternator??

[Time2Go]

Engine is Yanmar 4jh3e
fitted with two alternators with external regulators
2 battery starter bank
4 battery house bank.
all are lead acid
What’s the best way to configure?
My thoughts are to have one alternator
dedicated to the start bank and the other
the house with an ACR to transfer extra
charge capacity from the start bank to the house bank
Thoughts
Cheers
Neil

[smac999]

that will work. how big is the house bank? with only 4 batteries it's not going to take a lot of current for long anyways. unless they are big ones. so the 2nd one might not be doing much.

[Time2Go]

Originally Posted by smac999

that will work. how big is the house bank? with only 4 batteries it's not going to take a lot of current for long anyways. unless they are big ones. so the 2nd one might not be doing much.

The two start batteries are 700 cranking amps
in parallel
The house bank is 4, 200 amp golf carts
wired in series then parallel.
One thing I don’t understand is how the
start alternator/regulator knows when to
throttle back it output?
Is the ACR always going to be putting the two banks
together?

[Marathon1150]

We use the approach described in the OP - the stock alternator on a Volvo Penta 2003 charges the starter battery and a high output (140 amp) alternator and some solar panels charge the house bank (4 x 6volt AGM golf carts). The starter battery is also connected to the house bank with a Xantrex echo charger. When we bought this boat it did not have solar panels and the 2 x 100W panels seem to do the job in the summer.

On a second boat we have twice as much generating capacity via solar panels plus a wind generator and put all the power into the house bank. We use the same Xantrex echo charger to charge the starter battery. This boat has two 4D Lifeline AGMs and about the same number of amp hours as the golf carts.

A previous owner installed the second alternator on the first boat described above. The installation was very well done and must have been expensive. He also installed an arch which was only lightly populated until I installed the solar panels. Personally I would have chosen the solar panels and accepted the esthetic loss, as we have done, rather than spend the money on a huge alternator and be forced to run the engine to make power.

We are planning an anchoring out sail in the next couple of weeks to test how long we can last in a BC west coast winter without starting the engine. I suspect that if we are lucky it might be two days max.

[barnakiel]

If viable, I would use one small alt and one huge alt.


I would use the small one as the regular thing is used.


Then I would use the oversize thing as an onboard 'genset'.


I have seen it done with 4 kW alternators on one side of the engine.


b.