Electrical charging problems on volvo penta 7.4

[llewis01]

I have converted form a stock 55 amp alternator to a one wire 10si universal 200 amp alternator. I had to change the fuel pump from alternator connection to a oil pressure switch to turn off the fuel pump when the engine is not running. The choke wire I have wired to a 12 volt source. I have also upgraded the postive cable to 1 awg wire going thru a 200 amp circuit breaker then to a pro mariner 1 alternator 2 battery isolator. I presently have to alternator case ground going directly to negative bus bar. There is a smaller wire going from the negative bus bar to the engine block.
The problem I'm having is low amps coming out of the alternator. At 800 rpm's I'm getting about 30 or less amps. Rev the engine to 3000 rpm's the amp are a little less but it not constaance amps.
What I'm i missing? Had the alternator tested and they said it perform as it should. I hope I explained what I trying to do.

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[Scott Danforth]

1-wire alternators suck

 

[Bondo]

Ayuh,..... An alternator will only put out, what the battery calls for,.....

 

[llewis01]

I have a put a battery monitor to track what goes in and what comes out from the alternator. The monitor shows that we are barely maintaining the battery bank.

 

[alldodge]

1-wire alternators suck

Agree

pro mariner 1 alternator 2 battery isolator.

Cannot use a one wire with a isolator, the ALT is unable to see the Bat's. Use a ACR (auto charge relay) but there is a problem with the largest is 120 amp.

 

[Scott Danforth]

a one-wire alternator does not have a reference voltage back to the battery if going thru the diode in an isolator. there is a 0.7-0.9 volt drop across the big diodes in the isolator. so while the alternator sees output of 13.9-14.4 volts and shuts down (wherever the regulator threshold is), the battery sees only 13.0-13.7 volts which would barely keep a battery bank charged.

so you could wire the alternator directly to a battery and use an ACR for the second battery. that would charge the batteries fully as they would see full voltage

additionally, if wired directly to a battery, the regulator is hot all the time and that will kill the battery if not kept on a charger. a single wire alternator will have a lower voltage output compared to a 2/3 wire alternator as well. Learned that with hotrods 40 years ago

2/3 wire alternators require the excite terminal to "turn on" and they dont drain the battery if left for weeks on end between uses. a one-wire alternator is simply a 2-wire alternator where the excite wire is tied directly to the output.

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