Ground issue

[Sherman]

Greetings from southern Oregon,
I am having issues with the primary ground after replacing all four 6V house batteries. I have checked and have had others check my connections to make certain that all is as I took it apart. I took pictures as well to make certain that all cables were properly connected. Issue is, the primary negative cable arcs when touched to the negative battery post. I'm curious to know if anyone knows what the primary negative cable is attached to on the other end (battery isolator or?) or what the possible problem is.



My coach is a 2009 Holiday Rambler Scepter 42PDQ. My thanks in advance.


Jim

[twinboat]

It's attached to the inverter/charger. Anytime you connect one, it will spark as it's energizing.

[Persistent]

Basically Twinboat is correct.

The negative cable on the battery completes the circuit for all 12 volt devices. A charger provides power that can easily cause a spark. Inverters draw power that can cause a spark.

Many inverter/charger designs have a large capacitor on the 12 volt input/output. Charging the capacitor every time it is connected can easily cause a significant spark. There are lots of other possibilities.

It is best to turn all 12 volt devices "off" before disconnecting or connecting the batteries. Many owners install a capacitor charging circuit if they have an inverter/charger with a big capacitor.

Bag or tape all loose ends as soon as disconnected. Loose wires can cause significant electrical damage accidentally.

[Dutch Star Don]

Monaco used Magnum Inverters in most models during the era of your coach. Magnum recommends disconnecting the positive cable first and reconnecting the positive cable last when disconnecting batteries.

[153stars]

Good point brought up by Don....The reason is internally the Magnum can seek a ground in smaller circuitry and hurt electronics. The spark would likely be the same ,charging up inverter with pos. last as well though.
I follow Will Prowse for battery and solar info he has procedure he follows to charge hook up inverters every time. It's probably more to protect the BMS in Lifepo batts from surge.

Originally Posted by Dutch Star Don

Monaco used Magnum Inverters in most models during the era of your coach. Magnum recommends disconnecting the positive cable first and reconnecting the positive cable last when disconnecting batteries.

[kwftlaud]

my connection will spark when I complete the circuit. It doesn't take much current to produce a spark.
You can find out for sure if you have a problem by measuring the current that flows from the neg terminal to ground. You can do this with most volt meters. But be cautioned that setting up a meter to measure current can lead to destruction of the meter if its not done properly. Caution is merited.
I have ruined a few hand held meters in my day by just not paying attention to what I was doing.

Feel free to PM me if you want to do this yourself. If not any shop should be able to measure the current. Many things in a RV will draw some current when everything is off ( example, Propane alarm ) so some current is expected. But if everything is off, there should be less than 0.5 amp flowing out of the batteries when everything is off. This is often referred to as " parasitic " draw.

[153stars]

If your real worried to see amps AC/DC meter with max amp inrush function. I skipped it ,one I picked because I liked the white lighted screen on lesser model.

[Ray,IN]

The house battery bank should have 2 negative and 2 positive main cables. One of each goes to the inverter. the other neg. cable goes to the chassis frame and the other pos. cable goes to the main 12V distribution panel for the house part; otherwise you could not run 12V appliances without the inverter switch on.

[shootist]

It sparks mostly because the electrons flow from the negative to the positive. The positive is short on electrons, the negative has an excess. They just got to get home.

[Tha_Rooster]

Originally Posted by Sherman

Greetings from southern Oregon,
I am having issues with the primary ground after replacing all four 6V house batteries. I have checked and have had others check my connections to make certain that all is as I took it apart. I took pictures as well to make certain that all cables were properly connected. Issue is, the primary negative cable arcs when touched to the negative battery post. I'm curious to know if anyone knows what the primary negative cable is attached to on the other end (battery isolator or?) or what the possible problem is.



My coach is a 2009 Holiday Rambler Scepter 42PDQ. My thanks in advance.


Jim

I believe isolator is on the positive side. Triple check wiring could be something as simple like one battery turned around and hooked up wrong. 99% of the time when someone has battery problems after changing it’s they left off a wire or hooked up wrong.

[Mudfrog]

Originally Posted by Sherman

Greetings from southern Oregon,
I am having issues with the primary ground after replacing all four 6V house batteries. I have checked and have had others check my connections to make certain that all is as I took it apart. I took pictures as well to make certain that all cables were properly connected. Issue is, the primary negative cable arcs when touched to the negative battery post. I'm curious to know if anyone knows what the primary negative cable is attached to on the other end (battery isolator or?) or what the possible problem is.



My coach is a 2009 Holiday Rambler Scepter 42PDQ. My thanks in advance.


Jim

Hopefully remedied by now but didn't see this asked. How big an arc was it? As said, it's normal to have a little spark. And that spark would probably be even smaller if immediately disconnected then reconnected.

You can hook the cable to the battery, if the spark isn't too obnoxious, then use a clamp on DC amp meter to see the draw.

[shootist]

Originally Posted by Mudfrog

Hopefully remedied by now but didn't see this asked. How big an arc was it? As said, it's normal to have a little spark. And that spark would probably be even smaller if immediately disconnected then reconnected.

You can hook the cable to the battery, if the spark isn't too obnoxious, then use a clamp on DC amp meter to see the draw.

There is no draw as such, there is a difference in potential, once it equalizes there should be only a small draw by the various always on electronics. Capacitors are the biggest momentary draw.

[Forza Bill]

You want to see sparks? I worked on my 48V golf cart recently. That will get your attention!

[shootist]

Originally Posted by Forza Bill

You want to see sparks? I worked on my 48V golf cart recently. That will get your attention!

As in 4th of July🤣