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Twin engine installation with 2 WS500

I'm looking to install 2 WS500's for our twin engine boat my question related to the shunt or Shunts requirement. do we need 2 x shunts 1 per alternator or can we share 1 master shunt at the battery for the 2 x WS500s

Good Question.

If you have two relatively small alternators and are not concerned with limiting the output of each alternator you could go with a "Battery Centric" configuration and use only one shunt.  If you have large capacity alternators and want to be able to control and limit the output of each alternator independently then you will want a shunt placed at each alternator and set it up for am "Alternator centric" configuration.

you can read up on it in this manual:   http://wakespeed.com/Wakespeed%20%20Communications%20and%20Configuration%20Guide%20v2.4.1.pdf

I have the same question and I cant see anywhere in the manual that discusses the twin engine/twin shunt issue. No idea what "Alternator centric" might mean.

In my case, twin large case alternators (185A each @24V) sensing through a single shunt.

Not getting anywhere near the nominal output of the alternators.

Alternator Centric is an older term that I understand from WS is not being used anymore.  Basically it means control to the limits of the alternator, instead of the limits of the battery, and to do that the shunts need to go on the positive output of the alternators.

As to achieving nominal output, are your fields being driven to 100%?

Many alternators put out much less than they claim, especially once they have warmed up.  Its not unusual to see a 100A alt. not able to achieve 70A.

thanks, I should have rephrased all that about the alternators. My guess is, they are putting in as much as the batteries will accept. About the same current as when I engage my 3X chargers. (300A).

The problem is the alternators drop to float way too soon. 96% SOC, about 20A going in. I have "Exit amps set at 3A, but I estimate the system  drops to Float at 18A or so. The house loads are pretty steady, so I dont think the system is seeing a momentary current drop.

And returning to the dock, the Mastervolts have no problem charging to the correct exit amps. (return amps in Mastervolt parlance and tail current in Firefly speak.