need tech support for 0x66 250 charging system

[ttles714]

I have twin sx250's. Each is set up with its' own volt gauge. I have 2 batteries wired in parallel for the "house" with a separate volt meter for them ... The Port engine battery runs at 13.6 volts. The starboard engine battery shows 12.2-12.8.volts.... The house batteries always show the SAME voltage as the starboard engine battery. .... My understanding is that each motor has an auxiliary charging lead and both those auxiliary leads are connected to the house batteries. The house should be isolated from the motor starting batteries. I don't understand why the starboard battery and the house batteries show the same voltage. Is there a diode that can be bad, allowing the house to draw from the starboard battery. How is this isolated from within the motor ? I need to get into the bilge and double check the wiring, but I think its pretty straight forward. I don't totally understand the way the circuit works, so if anyone can shed some light on this for me before I get into it. .. Thanks

[99yam40]

do you ever put a charger on the house batteries?
Or do you depend on the running of starboard motor to charge those 3 batteries?
Does the voltage read that way even with motors running or just with all motor off?
Have you tried measuring voltages with hand held meter to make sure all are accurate?

[ttles714]

more info

yes ...when on the onboard charger the house and both starting batteries show an equal charge. This only seems to happen when there is a substantial draw on the house batteries when out (anchored over night). Start up in the morning and port reads 13.6, house and starboard read 12.2 and builds to 12.8 .... If I run a few hours, the starboard and house will come back up to 13.6... I can't figure out why the house and starboard batteries always read the exact same. and why the port is unaffected. I think the port is being isolated as it should be, however I also think the starboard is NOT being isolated. I am not sure how it is designed to be isolated or what enging component controls that. If I am thinking right, the port engine should also be charging the house batteries. Why would the house and Starboard be the same ? The manual shows 2 fuses, 80 amps... Not sure if they could have an effect. I did not get to check them yet.