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 > Do I need the ground lug to connect my new converter charger

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opnspaces

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Posted: 01/22/22 04:01pm Link  |  Quote  |  Print  |  Notify Moderator

After much deliberation I finally bought a new 3 stage charge converter for my trailer. Original post

It took a while to decide, but I finally settled on a deck mount Powermax PM3-45LK 45 amp converter charger. Powermax


Now for my question that hopefully someone can shed some light on. The unit has a positive and negative attachment point for the batteries. There is also a grounding lug that I am supposed to run to the trailer frame. Can I run the unit without the grounding lug attached? Since it has a standard 3 blade 120v plug I was curious if I can use the unit sitting on the floor of my garage to charge the batteries out of the trailer? My initial thought is yes I can. But in the back of my mind I seem to remember a post about the importance of running a separate ground wire from the grounding lug to the frame and not just connecting the two grounds together at the battery. Do I remember that right or did I imagine it?


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corvettekent

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Posted: 01/22/22 04:07pm Link  |  Quote  |  Print  |  Notify Moderator

You have to drill a hole in your garage floor and drive an 8-foot grounding rod down into the ground.

Just kidding, you will be fine without the extra ground wire.


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time2roll

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Posted: 01/22/22 04:14pm Link  |  Quote  |  Print  |  Notify Moderator

There should be a ground bus around someplace to connect the converter chassis ground


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Posted: 01/22/22 04:24pm Link  |  Quote  |  Print  |  Notify Moderator

Be sure the garage grounding rod is copper and be prepared to fall over and faint when you see the price. [emoticon]

OK Couldn't resist. Not sure why the ground lug for the trailer is needed since the plugs ground wire is also bounded to the frame, but perhaps some electrical standard safety practice. Perhaps the lug could also be for suppression of some electrical emissions.


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BFL13

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Posted: 01/22/22 04:38pm Link  |  Quote  |  Print  |  Notify Moderator

I don't bother with the "chassis ground" with my deck mount converters.

My Vector inverter user's manual says its chassis ground is to reduce radio and tv interference, but I don't know if that is what it is for on a converter.

Might as well add this photo of when I used the chassis ground as an anchor for a strain relief where I was having trouble with heavy cables with silky strands staying in the set screw terminals. That was on a 100 amp PowerMax. Never know--somebody might find that method useful.

">][image]

The don't mix grounds thing also came from the inverter world where you must not bring the chassis ground around to the neg input. Instead the chassis ground goes to the frame independently.

* This post was edited 01/22/22 04:45pm by BFL13 *


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Veebyes

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Posted: 01/23/22 06:59am Link  |  Quote  |  Print  |  Notify Moderator

Theoretically the negative to the battery & a direct to frame from the ground lug are the same.

There is nothing wrong with redundancy. There must be something nearby that the ground can be run to. My theory is that if the ground was not needed the lug on the charger would not be there.


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wa8yxm

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Posted: 01/23/22 08:09am Link  |  Quote  |  Print  |  Notify Moderator

Well.. You should likely ground it. But my personal opinion... Don't matter it's grounded already via othere leads and multiple grounds is NOT a good idea where I sit.


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Posted: 01/23/22 09:18am Link  |  Quote  |  Print  |  Notify Moderator

I presume wa8yxm is referring to a ground loop situation. But I agree that since the ground lug is there use it in the RV. Besides if you mount it on a metal frame member... Wait - 3rd ground?

opnspaces

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Posted: 01/23/22 09:36am Link  |  Quote  |  Print  |  Notify Moderator

Thanks, you all just reinforced my thoughts. So for now yes it will be additionally grounded when in the trailer. But when it's sitting on the garage floor charging batteries it will only be grounded through the negative to the battery. The additional ground lug will be ignored.

I did send a question to the Powermax people with the same question. I'm curious what kind of response I'll get.

time2roll

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Posted: 01/23/22 11:46am Link  |  Quote  |  Print  |  Notify Moderator

The chassis ground would only be for a permanent installation. Not needed for portable use.

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