Wiring fuel gauges to house batts?

I want to put separate fuel gauges in the engine room on each of my two gasoline fuel tanks and run it off the house batts (and not the ignition circuit). I 'm guessing the fuel reading will vary a little (?) with house batt charge, but I can adapt to that. Should I put a switch in the circuit so that they are not drawing current all the time? These gauges would replace my existing helm gauge.

I would..

Why would you want gauges in the ER vs the helm? And yes, have a switch to de-energize them.

Yep, add a switch so you can power the gauges when you want a reading. Since you only need to get that info every now and then, no need to waste power.

It may get a bit more complicated than this. If your current gauges are 12 volt then no problem. Some are 5 volt, and have a small transformer in the instrument panel.

Switches can be left on.

Push buttons can not.

The type of push button or toggle switches you need are described as "momentary".

Ski in NC said:

Why would you want gauges in the ER vs the helm? And yes, have a switch to de-energize them.

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It makes balancing the fuel draw from the port vs stbd tanks simpler.
I'll mount the gauges near the fuel tank valve.
(My flo-scan on the helm tells me how much total fuel I have left)

Momentary switch idea is great, thank you.

"My flo-scan on the helm tells me how much total fuel I have left)"

If you start with full tanks , and make a notation of fuel burned in the log , when you switch tanks , you can always know whats left in the tanks.

The flow scan is probably far more accurate than a fuel gauge.

FF said:

"My flo-scan on the helm tells me how much total fuel I have left)"

If you start with full tanks , and make a notation of fuel burned in the log , when you switch tanks , you can always know whats left in the tanks.

The flow scan is probably far more accurate than a fuel gauge.

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Indeed
The fuel gauges are a back-up

The fuel gauges are a back-up

WE use a dip stick, although with 5 gal per inch the flow scan is still the accurate measurement.

FF said:

The fuel gauges are a back-up

WE use a dip stick, although with 5 gal per inch the flow scan is still the accurate measurement.

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If you are moving fuel around to trim the boat (as I do) it's nice to have gauges in the engine room.


Jim
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"If you are moving fuel around to trim the boat (as I do) it's nice to have gauges in the engine room."

I guess.

AS out launch only has 100G per side , full or empty does not change trim much.

Fuse the guages and the wiring.

The momentary switch should/must be vapour proof for use in a gasoline engine engine compartment.

Be carefull of the wiring as any sparks could be disastrous.

FF said:

"If you are moving fuel around to trim the boat (as I do) it's nice to have gauges in the engine room."

I guess.

AS out launch only has 100G per side , full or empty does not change trim much.

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Chuckle. We are 380 gallons a side and the relative fill of tanks does change the trim quite a bit. We have 4 tanks. Fuel for the engine can be drawn from any tank but I typically draw from the forward tanks. Prior to fuelling, I move the fuel from the aft tanks to the forward tanks so the "older fuel" is in the forward tanks. All movement of fuel goes through the ESI polishing system. The "fuel dance" can take a couple of hours, so I plan it in advance.


Jim
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