what gauge wire to use

[2vets]

For the life of me I can not figure out the voltage drop charts. I am replacing my old 12 volt AGM Lifeline battery with two Lifeline AGM 6 volt 220 amp hour batteries. I had my 12 volt battery in my 1960 Tradewind in the rear closet curb side right next to the Progressive dynamics 4045K power converter system. I want to move the 6 volt batteries over to streetside right overland a bit forward of the axle so I do not have a lot of weight behind the axle. I believe I was heavier on the curbside anyways so I think this is a good move. I will connect the batteries with a 4/0 AWG in series. However I will need to now run about 20 feet of AWG under the bed where the batteries will be placed through the trunk and over to the street side closet. What gauge wire will I need and what will fit in my Progressive Dynamics converter? Please help- Lewster are you out there?? I was looking at the chart at bluesea.com and I believe I need entire circuit length in feet which would be 40 feet. It appears I would have to run 4 AWG which seems huge but perhaps necessary. Thanks in advance!

[2vets]

Forgot to say it was a single axle if that matters!

[reinergirl]

Originally Posted by 2vets

For the life of me I can not figure out the voltage drop charts. I am replacing my old 12 volt AGM Lifeline battery with two Lifeline AGM 6 volt 220 amp hour batteries. I had my 12 volt battery in my 1960 Tradewind in the rear closet curb side right next to the Progressive dynamics 4045K power converter system. I want to move the 6 volt batteries over to streetside right overland a bit forward of the axle so I do not have a lot of weight behind the axle. I believe I was heavier on the curbside anyways so I think this is a good move. I will connect the batteries with a 4/0 AWG in series. However I will need to now run about 20 feet of AWG under the bed where the batteries will be placed through the trunk and over to the street side closet. What gauge wire will I need and what will fit in my Progressive Dynamics converter? Please help- Lewster are you out there?? I was looking at the chart at bluesea.com and I believe I need entire circuit length in feet which would be 40 feet. It appears I would have to run 4 AWG which seems huge but perhaps necessary. Thanks in advance!

I can’t help her because I suck at electrical but just thought I’d bump this for my twin sister, so that she can get some feedback!

[nvestysly]

I ran about 40 feet of cable from our truck charging system (under the hood) back to the bumper to a heavy duty connector then to the front of the trailer under the couch. I wanted very little voltage drop. I used 2 gage wire. In some ways it was overkill but I got what I wanted... almost immeasurable voltage drop.

[TowmaterATX]

Your converter is limited to 45 amps.
If you allow for a 2% drop at 13.8 DC you need 1 AWG at 40 feet wire run.
If you're okay with a 5% drop, you'll only need 4 AWG.

Do you have a inverter? If it's in the same place as the converter you'll want to size for the draw amps for the inverter since they are likely higher than your converter's charging amps.
If you have an inverter at 1000W you'd be right at the edge with 2/0 AWG and should probably do 3/0 AWG. That is a horrible size to run that far, so if you have an inverter I'd recommend putting it with the batteries and run much smaller 110V wires back. The wire size handles the amps, so at 110V with a run at that length you would be more than covered by normal household romex 14/2 w/Ground.

[TowmaterATX]

After I answered this question, I had a feeling I wasn't quite right and kept double checking things. I was answering for THHN style wires and incorrectly didn't consider the battery/welding cable types. You should be able to run 6ga welding/battery cable for that run without problem. 4ga if you want to future proof for a 1000W inverter or something. Sorry if my previous answer led you astray.