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glidin avatar image
glidin asked

How to best ground my Phoenix 12/800 - 120V Inverter

I have been running sensitive sonar equipment off a battery on our vessel, this battery is also connected to the Phoenix 12/800 Inverter. When both the sonar and inverter are running there is "noise" present in the sonar echogram, apparently this can happen if the ground is to the chasis and not the negative battery terminal. Is it OK to connect the ground to the negative battery terminal?


Thanks for the help

Grounding
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1 Answer
kai avatar image
kai answered ·

https://community.victronenergy.com/questions/7231/do-i-ground-twice.html

Chassis should be connected to the (boat) system ground - where ever that is for safety reasons.

That may or may not be the negative battery terminal depending on how you're configured.


If it resolves the noise issue, great. Otherwise you might have to think about different forms of filtering, separation or managing the loop areas of circuits.


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glidin avatar image glidin commented ·

Thanks Kai,

Whats the worst that could happen if I ground to the negative terminal?

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kai avatar image kai ♦ glidin commented ·

Don't know - I haven't seen how your system is wired up. Do you have a photo or sketch that shows the inverter, sonar and wiring?

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glidin avatar image glidin kai ♦ commented ·

Thanks Again Kai.

Not on me currently, and I am away from the boat, but it is quite simple. The inverter has a positive lead to the positive terminal and a negative lead to the negative terminal. There are a few other leads off the battery going to a few DC outlets. I talked with my brother-in -law electrician and he recommended removing the ground wire entirely to see if the problem improved. He was concerned that the ground wire and negative lead were different sizes, and would create a circuit if grounded to the negative lead. The current noise could be due to a small amount of current grounding into the hull of the boat, and infiltrating the sonar.

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kai avatar image kai ♦ glidin commented ·

I guess as long as your negative battery terminal is connected to the hull (i'm assuming hull is metallic), and you connect the chassis to the negative battery terminal, you're covered from a safety perspective. But I'd defer to your electrician on the safety element.

The inverter manual says the chassis must be grounded (i.e. connected to an earth reference, which for a metallic boat is the hull)


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glidin avatar image glidin kai ♦ commented ·

Thanks Kai,

Great help here. I will look to ground the inverter to the hull at a different location, hopefully that helps remove the noise.


Cheers

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JohnC avatar image JohnC ♦ glidin commented ·

Take care doing this. Multiple hull grounds on a boat can lead to stray currents and electrolysis (corrosion) issues.

By all means try it to test, but perhaps seek professional advice before leaving it like that.

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