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Old 04-27-2014, 06:22 PM   #1
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Cables for battery upgrade

Hi Jayco Owners,

I'm upgrading to two 6v batteries. I plan to spend as much time boondocking as we can.

When it comes to replacing the batteries I keep reading about the need to make sure all cables are the "the same length and adequate guage". It seems that Most recommend 4gauge?

QUESTIONS: Do I need to rip the POSITIVE wires out of the Jayco to upgrade to 4 guage? If so which wires? How far do I need to rip the existing wires out to? I.e., from the battery box all the way into the TT at which point? To the converter?

Then the Negative cable attaches to the frame about 2 feet from the battery box, then continues on. I assume that is #8 or #10 as well. Do I change up to the frame? Or change out all the way into the TT? If all the way how far, again to the converter?

Or lastly do I even need to change? Is the concern simply about the battery to battery (series) cable?

Any advice is greatly appreciated!

Thank you.

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Old 04-28-2014, 03:19 PM   #2
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The heavier the wire the better off you are. I use #2 invertor cables but I use two 12v batteries that way I don't have to change the converter (two 6v batteries in series need 15.5v to fully charge) and if one battery fails I can disconnect it and still use the single 12v battery that is still good. Are you going to carry a spare 6v battery?

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Old 04-28-2014, 04:27 PM   #3
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I just installed four 6V Deep Cycle Batteries. So what I did was have a local battery supplier make me 2/0 cables for connections between the batteries and the ground. I didn't upgrade the cables leading to the battery bank since I'm not installing an inverter at this time so demand will not be higher than just the stock batteries. If you are planning to run 120V items through an inverter then I would place the Inverter vary close to the batteries with large cables. I carry a Genius Charger so when I'm not using the trailer and have power I can charge the bank.
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Old 04-28-2014, 05:14 PM   #4
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there have been discussions on JOF about the advantages of twin 12 V batteries as well, where if one of the (2) 6 v batteries ( or one cell in a battery) goes, you are out of luck, where with (2) 12 V batteries, you can remove the bad one and still have some power.

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Old 04-28-2014, 08:35 PM   #5
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[QUOTE=wwsmith111;193320] (two 6v batteries in series need 15.5v to fully charge) QUOTE]

The only time the batteries should be subjected to 15.5VDC is during Edqualization. Most RV charge controllers are not sophisticated enough to do a true Equalization (15.5VDC)and only Equalize at around 14.6 to 14.8VDC, as they have no way of monitoring the battery's temperature. At 15.5VDC, the battery will begin to boil and possibly do a worse things (like explode) if its temperature is not monitored. Some battery controllers will equalize based on a specific amount of time, which is not as effective as monitoring the batteries internal temperature before moving to the absorption mode.

(Flooded Batteries)

Equalization Mode =
- 6VDC battery = 7.8 VDC
- 12VDC battery (or (2) 6volt batteries in series) = 15.5 VDC

Absorption Mode =
- 6VDC battery = 7.4 VDC
- 12VDC battery (or (2) 6volt batteries in series) = 14.8 VDC

Float Mode =
- 6VDC battery = 6.6 VDC
- 12VDC battery (or (2) 6volt batteries in series) = 13.2 VDC
(+- .01VDC)

Above numbers are on Trojans website
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Old 04-28-2014, 09:25 PM   #6
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To get back to your original question, you probably have 8 gauge wiring between the converter and the batteries. You can draw 30 amps through the wiring for lengths up to about 12 feet. This would include the positive and negative wire runs, but not the ground path that travels though the trailer frame itself, if the frame is used for the ground. I can't imagine loads really that high. The wire between the two batteries can be of the same gauge. If you anticipate huge current draws, using an inverter, or have really long wiring runs, you should go to 4 gauge wiring. Otherwize don't worry about it.

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Old 04-28-2014, 10:20 PM   #7
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The way I thought about it, the draw is across the battery bank, neg. from one pair and pos. From the other pair, so I wanted large cables so the bank draw down was even.

I'm not going to get into the 12v versus 6v or what is or isn't a deep cycle battery, everyone who is debating a change should do there own research and make their own decisions. I made mine good or bad.
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Old 04-29-2014, 12:45 PM   #8
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Since you do not appear to be doing anything but changing to 2-6's then just use the 4ga to connect the +from one battery to the - of the other battery. leave the rest as is..
I used 00ga on mine but that was for hooking up the 2000 watt whole house inverter. The original 12 V wiring was left as is.
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Old 04-29-2014, 03:50 PM   #9
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I was referring to the converter which needs to be able to put out 15.5v in order to properly handle the two 6v batteries in series. I was trying to keep it simple and not get into all the details which have been beat to death multiple times. I just was trying to let him know that unless he changed his converter he would have a problem.
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Old 04-29-2014, 07:42 PM   #10
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Welcome to JOF

Originally Posted by MTDreams View Post
snip.......I'm upgrading to two 6v batteries. I plan to spend as much time boondocking as we can.....snip
I also upgraded to (2) 6V deep cycle batteries a few years back for my boondocking and they have worked out extremely well. Like with any battery bank proper maintenance will insure many years of service.

Here's my upgrade: https://www.jaycoowners.com/forums/sh...upgrade&page=2

No, I don't carry a spare 6V battery.



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