Dual voltage gauges

[Kirk Gibson]

Hello,
2011 256CC Seafox w twin F150s:

I verified each engine charges one of 2 batteries when on pos. 1 of the battery switch. Then when combined batteries equalize (duh).
These are the only 2 positions on my switch.

The Yamaha gauges that are on the boat (not Command Link) are standard...so the top gauge will only give me the battery reading of 1 battery.
I want to see the voltage of each battery so I bought 2 volt gauges and installed them next to each engines tach. Works great for each engine.
Now I haven't run both engines at the same time yet on the "combine" mode.
I am wondering if there might be a "sneak circuit" back through the voltmeters which might damage an alternator if I run both engines while in the combine mode. The voltmeters have a ground lead, battery lead, 12V ign. lead and light lead. I obtained the 12V ign. source from behind the ignition key switches (yellow leads coming out of top) for port & starb. As per voltmeter instructions I installed a 1A inline fuse in the 12V ign sources.

Does anybody have dual voltmeters on a dual engine setup that knows if this will be ok in combine mode. I know it is seperate in pos. 1, I feel it will be ok but I just want to verify things.

Thanks
Kirk

[boats.net]

Voltmeters just read key on voltage(battery voltage) and are not connected directly to alternator output and wont affect charging system regardless what position battery switch is in.

[Kirk Gibson]

Thanks

Thanks that's what I thought ... they read independently when switch on pos. 1 (shows each battery voltage connected to each engine) and when batteries are combined both gauges read identical. Thanks again for the conformation. I would only run it on combine if I ran down the either of the batteries anyway then I would switch it back to position 1 after I got them started.
Thanks
Kirk