Multiple battery, grounding, good, bad, ? ?

[roscoe]

I rebuilt my boat a few years ago. Including a complete rewire.
All worked well. Everything is wired correctly, well, except for not to ABCXYZ... boat wiring colors.
This year, installed new sonar units, and they seem to be more sensitive to low voltage (when starting the main motor).

I decided it was time to add a second battery for accessories, and also to save my starting battery for the motor.
This solved my issue with the sonars, but created a new one.

When I wired the boat, I installed a separate fuse/switch for the gauges, as I don't like the dash lit up all the time when fishing or driving at night. I would like to keep this option.

So, the gauges are powered off the ignition switch (house battery), the gauge lights are powered off the fuse panel, the fuse panel is connected to the new "house" battery.

All the gauges have a single ground connection on the back, which grounds the gauge function, AND the light.
The ground wires from the gauges run back to the ground buss next to the fuse panel, and then back to the house battery.

The problem: There is no ground connection back to the starting battery, so the gauges do not work.
If I put a jumper between the main battery and the house battery negative posts, all the gauges function.


? Is it acceptable to have the two battery neg posts connected?
Will it cause and problems or damage ?
Is it a problem to have the gauges and gauge lights grounded to both batteries?

If this is not ok, what are my options?

I really would like to keep the gauge lights.

If need be, I could eliminate the gauge lights and run a new ground wire back to the main battery, which would be a pain as this is a center console boat, batteries at stern. Could I tie into the ground side of the KILL switch ?

Your insight will be greatly appreciated.

 

[alldodge]

Your engine gauges are for your motor, they need to be connected to the starting battery. Connecting them to the house battery does not give you the true pic of your motor.

Grounds on both batteries should be connected together. Grounds will not cause any issues with any of your electronics of starting battery.

Run a separate 10 AWG wire which is fused for 30 amps and close to the house battery. Run that wire up to a new fuse panel or Buss bar/terminal block. The fuse panel can hold all the fuses for the electronics or if using a buss bar, run spate fuses to the electronics.

Dash lights are an easy fix. Find the fist gauge light bulb which is feed by the ignition switch. Disconnect this wire from the bulb and run it to a single pole single throw switch. From the other side of the switch run it to the bulb connection. Now you can leave them on or turn them off

 

[sam am I]

? Is it acceptable to have the two battery neg posts connected?

Yes, that is how normally they are wired. Unless you are stacking in series to create 24V, 36V

Will it cause and problems or damage ?

No

Is it a problem to have the gauges and gauge lights grounded to both batteries?

No, because of answer #1......Both batteries grounds are one in the same since they are tied together........

If this is not ok, what are my options?

N/A

If need be, I could eliminate the gauge lights and run a new ground wire back to the main battery, which would be a pain as this is a center console boat, batteries at stern. Could I tie into the ground side of the KILL switch ?

N/A

 

[roscoe]

OK guys, thanks for verifying this.
Didn't want to do extra work if not needed.
Yes, the gauges are powered by the motor, just the gauge lights are powered by the house battery.
And yes, the fuse block is fed by a separate fused power lead.
And both batteries have their own separate disconnect switch.

Your help is appreciated.