genset battery circuit voltage too high?

[Captain Bill]

Ok, what did I do wrong. I've had an ongoing problem with my genset battery chaging circuit and my battery charger fighting each other. My rather simple minded Xantrex battery charger decides what it should do to my batteries by shutting down every 10 minutes or so and looking at the battery voltage. This is all well and good except that when I'm running on the genset the genset starting circuit is putting out 10 amps and running the voltage up so I cannot even get close to a full charge as the battery charger reads the genset voltage and thinks it's done. Since I have AGM batteries I need to get them to 100% once in a while. So in my apparently not so infinite wisdom I try a simple solution. I move the battery positive connection from the house bank to the start bank. Tha battery banks have a common negative. Well now the battery charger is very happy and doing what I expect. The problem is that the voltage on the start bank is now 15.5!!!! All power was off when I moved the connection so I don't think I blew the voltage regulator. Does anyone have any idea why it's not regulating? The wiring diagram shows the voltage regulator sensing off of the B+ so I would think it would be measuring what ever battery the B+ circuit was connected to.

[Sailmonkey]

Eliminate the generator charging circuit?

Is this a bridge rectifier from the generator or is it a small alternator on the generator?

[Captain Bill]

It can be disconnected without affecting the starter so that is an option should I not be able to figure out what's going on.

[hellosailor]

15.5 sounds like you've gotten one of your charging sources into "equalize" mode, and most AGMs won't tolerate that.

Putting two chargers together and letting them fight for control is a good way to drive one or both mad. Disconnect one or the other and find out which one is no longer regulating it's output.

[Captain Bill]

Originally Posted by hellosailor

Putting two chargers together and letting them fight for control is a good way to drive one or both mad. Disconnect one or the other and find out which one is no longer regulating it's output.

That is exactly why I moved the genset start circuit to the start bank, the start circuit voltage regulator and the Xantrax battery charger were fighting each other. The only charging source on the start bank at the moment is the genset start circuit and it's as dumb as they come. That is there is no equalize mode.

[hellosailor]

If the genset by itself is the only thing connected and it is putting 15.5 on the battery? Bad regulator in the genset. Sometimes that's got nothing to do with how anything was used, just a simple coincidental failure.