Replacing Battery Cables from Dealer

[CA-2503S]

I wasn't impressed by the second battery wiring hook up that the dealer did when we took delivery of our 2503S





... so I finally got around to digging into how to wire it and what gauge wire to use and came up with this ...


Using new battery cables from an automotive store - 4 Gauge (overkill, I know) - I connected the batteries to pull equally from both.



Comparison of the unmarked ~10-12 gauge wire vs the 4 gauge battery cables





Still showing 12.56v across both batteries and they should evenly charge now vice loading up the first battery.

Cheers!

[CedarCreekWoody]

Good upgrade.

[CHICKDOE]

i see why you weren't impressed. it looks like the black and white cable between the two batteries is even smaller than the feed cables attached to the one battery. and black and white? was it just a piece he had left over from a 110 vac wiring job? the overkill will not hurt a bit!

[gectisme]

Same Batteries same cost savings wiring from the dealer, guessing you are from CA, "CA-2503S", Best RV by any chance? I did something similar, except I had welding cable laying around and crimp connectors from work so I made mine own.

[SidecarFlip]

Couple real good sources for battery cables (pre made) and welding cable by the foot and solid copper crimp connectors... Dell City Electronics for the pre made cables and Tractor Supply for welding cable by the foot and solid copper crimp on connectors.

You always want as heavy a cable as you can get to provide minimal amperage loss.

Just an FYI...

[Jay2504]

Wow. That dealer either didn't know or didn't care about how to wire it right. What you did is excellent! Now the battries will charge equally. Look at the other end of the neg cable comming from the unit. If it is like mine was its just hooked to the frame with a self tapping screw. Drill a hole in the front crossmember and run a number 4 cable from the neg terminal of the batt and bolt the other end to the hole that you drilled. Be sure and clean off the paint for good contact. This is the first step to cutting the resistance from the converter to the battires. Jay

[D. J. Schuler]

Nice upgrade, DC - direct current volts/amps is very dependent on wire size and length of run, just ask Thomas Edison or Nikola Tesla.

[OldBob]

4 Gauge is not an overkill. I consider it a minimum.

[BooHyde]

Your upgrade is what the dealer should have installed to begin with. Looks good.

[sgtlm17]

I'm always amazed to see or hear about how dealers who are in the business can't do a simple task correctly. Your batteries are now connected as they should be. Shame on that dealer.

[muddyrode]

I just add a second battery and a disconnect switch to my new sandpiper and I used some 4 awg welding wire I had left over from wiring out a DC
Telephone PBX and use crimp connectors
As this is my third unit to add a disconnect to

[pmsherman]

Your first picture showing the dealer's wiring indicates that the dealer didn't do a bad job of connecting the two batteries together even though they "forgot" to change the feed line to the fuse panel to correctly balance the load on the batteries. The minimum size wire that should be used to connect the batteries is the same size wire that feeds the fuse panel. While larger wire is desirable when connecting batteries together, it is more expensive and a little bit harder to work with.

The greatest draw on your battery will occur when the furnace is running and you turn on a faucet, causing the water pump to run. Add a few amps for lights and you'll be approaching a peak load of less than 25A, more likely 20A. Your slide motor probably draws no more than 20A but you'll probably never open or close it while the furnace is running. #10 wire, rated for 30A is what I'd expect Forest River to use between the battery and the fuse box.

I needed much larger wire in my Georgetown because I added an inverter which can draw almost 100A from the battery. My larger slide also draws more power from the battery when its motor is running. WIring requirements for any type of RV are very dependent on exactly what electrical loads are supplied with the rig and what you, as owner, add to it.

Phil

[gectisme]

Originally Posted by pmsherman

Your first picture showing the dealer's wiring indicates that the dealer didn't do a bad job of connecting the two batteries together even though they "forgot" to change the feed line to the fuse panel to correctly balance the load on the batteries. The minimum size wire that should be used to connect the batteries is the same size wire that feeds the fuse panel. While larger wire is desirable when connecting batteries together, it is more expensive and a little bit harder to work with.

The greatest draw on your battery will occur when the furnace is running and you turn on a faucet, causing the water pump to run. Add a few amps for lights and you'll be approaching a peak load of less than 25A, more likely 20A. Your slide motor probably draws no more than 20A but you'll probably never open or close it while the furnace is running. #10 wire, rated for 30A is what I'd expect Forest River to use between the battery and the fuse box.

I needed much larger wire in my Georgetown because I added an inverter which can draw almost 100A from the battery. My larger slide also draws more power from the battery when its motor is running. WIring requirements for any type of RV are very dependent on exactly what electrical loads are supplied with the rig and what you, as owner, add to it.

Phil

Unless I am looking at the picture wrong, the wiring is not very good from the dealer. The wiring from the trailer goes to one battery and then the jumpers to parallel the 2 batteries is smaller than the trailer wiring. This is how mine was too until I rewired and added bigger jumper wires. The wires from the trailer now have the positive on one battery and the negative on the other battery.
[emoji106]

[SidecarFlip]

Originally Posted by gectisme

Unless I am looking at the picture wrong, the wiring is not very good from the dealer. The wiring from the trailer goes to one battery and then the jumpers to parallel the 2 batteries is smaller than the trailer wiring. This is how mine was too until I rewired and added bigger jumper wires. The wires from the trailer now have the positive on one battery and the negative on the other battery.
[emoji106]

Exactly, you always run from one negative terminal on one battery and a positive on the other. That balances charge and discharge across both. In the case of three batteries , the center battery is parallel jumped to the two others and I use welding cable and solid copper crimp on lugs.