Ground Wire from Inverter getting hot, I have a few ideas but looking for advice

[neoneddy]

Took the bus out a few times now, and my inverter must be pulling more juice as the summer heats up because the insulation on the negative terminal (plastic sleeve) is melting.

Now the odd thing is, the positive side is ambient temp.    I use 1/0 gauge wire (thick as my thumb)

Below (attached graphic) is how I have my battery setup with my house batteries / alternator/ etc

I'm  considering adding an additional ground near the inverter.. or not even grounding near the coach battery at all, just using a chassis ground near the inverter.

[Brassman]

A bad connection at terminal or crimp could cause the heat.

[neoneddy]

I should check my crimp, the connection is solid at the terminal end though.

I might get out the touch and solder it all. (terminal to wire)

[Dave5Cs]

On my Magnum it said to not ground the batteries directly to the frame etc. but to put a ground wire from the inverter to the frame or metal body etc. It had a screw terminal on the end of the inverter and I connected it to the frame with a 10 gauge wire as per instructions. Also have a 300 Amp fuse breaker on the Positive wire and a breaker also on the negative from batteries to inverter.

[Jon]

I have never heard anyone use 300 amp and 10 Ga wire in the same sentence.

[thomasinnv]

I have never heard anyone use 300 amp and 10 Ga wire in the same sentence.

I believe he was referring to the chassis ground lug on the inverter case, which is different than the main inverter battery ground lug.

Sent from my SM-G920T using Tapatalk

[gumpy]

I have never heard anyone use 300 amp and 10 Ga wire in the same sentence.

Actually, he used the terms in two different sentences.  He was referring to the chassis ground when discussing the 10 ga wire. He was referring to the battery positive connection when referring to the 300 amp fuse. Everything he said was correct, though I question the instruction about not grounding the batteries to chassis.

[brmax]

Yes as mentioned the magnum is calling it equipment ground. The terminal can handle  ( i believe it said ) 14gauge through 2. Sorry i closed out the pdf
The magnum manual illustrations im seeing are cables running straight to inverter, no stops unless optional dc shunt kit is installed on neg cable. The fuse and switch could be on pos cable like Dave was saying.
I guess the key here is what your inverter instalation describes. I mighta missed it in one of the videos, sorry. But hey its Friday

Good day there
Floyd

[neoneddy]

Grounding At Inverter not battery
This makes sense because the electron flow would need to go another hop. from inverter to battery negative then to ground / chassis.

Picked the bus up from the glass shop (thanks Glass Today in Minneapolis) and warmed it up, turned on the AC and smelled something while checking tire pressure (I'm super paranoid about PSI on my tires), I opened the battery door and the end was now smoking, felt super warm.   I did leave my inverter on while it was at the shop to keep the fridge cool.  So I'm thinking the battery banks were a bit low and everything was sucking lots of juice.

I think I'm going to shorten that cable  up and ground at the chassis, because that's essentially what happens now, just after a longer run.  Yes it's 1/0 cable, but I figure I'll double up my grounds and shorten the cables.  I shot some video, I'll post it up soon.

[brmax]

If your thinking is having one ground path. Some interesting pages i seen in link.
I wanted to mention this because of a few designs in grounding the magnum.
The wiring plan chosen assigns a size of ground wire one can use. Im sure some others can easily describe this better than me.
In the meantime a nice page i found in a link below, though this is for a MS series Magnum so again it depends on our brand and i been looking at this one lately. Anyway on page 35 i believe it starts, and are ground wire designs and show a great deal on sizing with chosen design. hth

Floyd

http://pdf.donrowe.com/ms_series_owners_guide.pdf

[Oonrahnjay]

     Is anyone else wondering why there's so much power going down a plain chassis ground during normal operation??

[Darkspeed]

First guess would be a ground loop. do you have neutral tied to ground / frame anywhere other than your inverter?

When the engine is running? when the generator is running? or all the time?

[bevans6]

Melting insulation on a connector says the connector is faulty, unless the whole wire is hot the whole length of it.  The resistance is what causes the heat, and the fault can be between the cable and the connector, the connector and the battery/inverter, or can be internal to the battery or the equipment.  It's perfectly permissable to use the chassis as a major conductor path - all the the bus electrical system does, and pushes up to 6000 watts from the alternator, and much more than that when the starter motor is operating.  Unlike a neutral connection, many ground connects are permissable and recommended.  You can ground everything, and unless a fault condition exists all of the grounds will be at the same potential.

You say you were running one AC unit when you found the hot connector.  That is around 1800 watts on the 120VAC side, maybe 2000 watts on the DC side, your picture suggest 28 volts so around 75 amps.  Well within the acceptable range for 1/0 cable.   I personally don't like soldered connectors, and prefer properly crimped ends.  Usually replacing the cable end and cleaning and using correct grease on the connection clears these issues up.  Sometimes the cable corrodes internally and needs to be replaced.  I know it's not the ultimate cable for the application but I use welding cable, and up-size the cable vs the rated ampacity.  I like the flexibility of welding cable, and it's very weather-proof.

[HB of CJ]

Interesting situation.  Excellent input given.  Ground loop?  Proper Crimping concerns?  Insufficient cable diameter?  Run length?  Has anybody considered a dedicated house ground?  

I also would be curious as to what is causing the hot inverter ground wire.  Very heavy fine over size stranded mining cable does come to mind also.  Is the inverter running hot?

[neoneddy]

Inverter is running fine..

I'm 95% sure I just have a bad crimp.   I'll trim , recrimp and solder it.