Negative Inverter Cable?

[mrgscooter]

I'm installing a shunt to my 12v system and my Thor diagram shows a negative cable going to my battery compartment. However I've checked the cables in my compartment and no negative cable. I checked the inverter and it's got a negative #4 cable connected and looks like it runs out below the floor. Unfortunately under the floor looks like it comes out above the gas tank. Any ideas as to where that negative cable might be? Any help would be appreciated.

[Judge]

The proper way to wire an Inverter is to have it less than 5' from the batteries and using the proper gauge wire and connected directly to the battery terminals with a proper rate fuse. Thor does not always do it that way.

I had an '18 Outlaw 29H and the Inverter was in a back storage compartment.... about 20 feet from the batteries. They ran the negative cable to the chassis ground, which is an incorrect installation. They also used wires that were far too small for the length of the run let alone the run being too far from the batteries.

You are going to need to try to trace that wire to see if it goes to the negative post on the house battery or if it goes to a chassis ground.

[mrgscooter]

My inverter is about 20ft from batteries. The positive cable is #4 in size and there are definitely no negative inverter cable coming to the batteries. From what I've read so far, the inverter indeed should be located close to the batteries. Is the only issue with a greater distance then voltage loss from the battery to the inverter? When I've measured the voltage at the inverter and the batteries, I get the same reading?? Does anyone know if I move the inverter if I should also relocate the converter too? The next place I'm going to look for the negative inverter cable is near my generator; it looks like there's a ground stud over there.

In hindsight it sure looks like it would have made more sense to locate the battery compartment near the generator.

[Judge]

Originally Posted by mrgscooter

My inverter is about 20ft from batteries. The positive cable is #4 in size and there are definitely no negative inverter cable coming to the batteries. From what I've read so far, the inverter indeed should be located close to the batteries. Is the only issue with a greater distance then voltage loss from the battery to the inverter? When I've measured the voltage at the inverter and the batteries, I get the same reading?? Does anyone know if I move the inverter if I should also relocate the converter too? The next place I'm going to look for the negative inverter cable is near my generator; it looks like there's a ground stud over there.

In hindsight it sure looks like it would have made more sense to locate the battery compartment near the generator.

Sounds like Thor wired your Inverter the way they did the one on my old Outlaw 29H.

You may read the same voltage at rest, but under load you will have a large voltage drop and current that is much too high for 4AWG causing the wiring to become very got.

The when you add the fact they didn't run the (-) cable to the battery post, that makes matters even worse.

A 1000W Inverter should have 2AWG less than 5 feet long and an 1800W Inverter should have 2/0AWG less than 5 feet long with both cables connected to the battery posts and an appropriate rated fuse.

Now if you are just trying to charge a phone or tablet or something not requiring a lot of power, you may get by ok. But I would not be trying to use a lot of Inverter power with that wiring job.


From the Converter perspective, it's a similar deal. The further the Converter is from the batteries, the heavier gauge the wire should be. Otherwise when you deeply discharge your batteries, the Converter will work much harder and take much longer to get them to a full charge.

[MLP]

Running two or more #2ga wires to reduce the dc resistance will satisfy the length problem. I own tools to do just that. Resistance of a #2ga wire is approximately .16 ohms pr 1000 ft. Break that down to .00016 ohms per foot. 20 feet is .0032 ohms x 2 = .0064 ohms. Both the supply and return lengths need to be taken into account. Take the max current times the total resistance will give you the total voltage loss. 100 amps you will loose .64 volts. This does not include the resistance of any connector or mating surface. If clean, should be in the low milli ohm range or lower.

[Judge]

This is Xantrex specs for their most common 1000W and 1800W Inverters.

[mrgscooter]

This all started by upgrading to 2-100ah lithium batteries, lithium converter & lithium bim. I guess I need to evaluate which is better/easier to move the batteries or move the converter & inverter. At first glance it might be the converter & inverter but I hate giving up the storage space next to the battery compartment.

Related topic, any ideas as to what I should do with my old batteries (4yrs old), converter & bim?