Moving Batteries to Rear

qtla9111 · 11-29-2015, 09:07 PM

I have been toying with many ideas to improve my rving overall and boondocking. I have a 235W Panel and two 6V batteries. The system works fine but I find the tongue weight still drops down the rear end of my Durango SUV. The tongue weight on the 230DS is somewhere around 690 pounds. I have the two LP tanks and the two batteries.

I have to remove the LP tanks to work on the batteries and there are no battery boxes that fit in the small space. I have to clean the cable connectors constantly and weather wreaks havoc on the exposed cables.

I want to reinforce the bumper, add a battery box and four 6V batteries. I like power and don't want to have to constantly conserve. That said, we're not big users.

How much weight can I transfer from the front to the back without jeopardizing safety? Can this be done?

I have a trip coming up in the next month and would like to do this mod. Thanks in advance.

**LJAZ** · 11-30-2015, 08:25 AM

How much do the batteries weigh? As long as you keep the tongue weight between 10 - 15% of the trailer weight you should be OK. Unfortunately there's no real easy way to calculate what the difference will be, so you'll likely end up having to go the trial and error method.

qtla9111 · 11-30-2015, 10:06 AM

Quote:

Originally Posted by LJAZ

How much do the batteries weigh? As long as you keep the tongue weight between 10 - 15% of the trailer weight you should be OK. Unfortunately there's no real easy way to calculate what the difference will be, so you'll likely end up having to go the trial and error method.

They are two six volt and weigh 68lbs a piece.

profdant139 · 11-30-2015, 12:59 PM

The real trick is in reinforcing the bumper sufficiently. It is not designed for that much cantilevered weight -- you risk metal fatigue. But if you know how to weld and you can really beef up the hardware back there, you should be good to go.

I am sure you know that you will need thick cable running to the converter and also running to the seven pin plug -- if the wire is too thin, there will be too much resistance. I think ten gauge will do the job, but I am not sure. Twelve gauge is too thin, I think. (Bigger numbers mean smaller wire, for some reason.)

Good luck with this mod! Also, have you considered upgrading the rear suspension of your tow vehicle? And are you using a weight distribution hitch? That may prevent the dreaded "squatting truck" syndrome.

qtla9111 · 11-30-2015, 02:31 PM

Quote:

Originally Posted by profdant139

The real trick is in reinforcing the bumper sufficiently. It is not designed for that much cantilevered weight -- you risk metal fatigue. But if you know how to weld and you can really beef up the hardware back there, you should be good to go.

I am sure you know that you will need thick cable running to the converter and also running to the seven pin plug -- if the wire is too thin, there will be too much resistance. I think ten gauge will do the job, but I am not sure. Twelve gauge is too thin, I think. (Bigger numbers mean smaller wire, for some reason.)

Good luck with this mod! Also, have you considered upgrading the rear suspension of your tow vehicle? And are you using a weight distribution hitch? That may prevent the dreaded "squatting truck" syndrome.

Thanks Dan for the answers. I have a guy who can do the welding work and I told him it has to be strong and welded to the frame. You know we have the dreaded "topes" (speed bumps) and I wasn't so lucky this last winter so I don't want any issues.

On the cables I am wondering what gauge to use. It will be 20ft in length. Any ideas?

For those of you who may or may not know Dan, he is a great photographer and has posted some wonderful pictures. I don't know if you post them here or not but they are pretty cool and he has gone to some great boondocking spots.

profdant139 · 11-30-2015, 03:24 PM

Chris!! I did not even realize that was your post -- welcome back to the Club! Thanks for the kind words!

I think that there are charts on the Web for cable sizes, depending on the length of the run. Whatever size you choose, someone will always say "not big enough!"

And have you thought about a diagonal brace or truss under the back battery shelf? The real enemy is vibration, causing the metal to flex and crystallize.

One more issue -- by extending the back, might you risk bottoming out when leaving a steep driveway? If you already have a lot of "escape angle" clearance, this will not be a problem.

qtla9111 · 11-30-2015, 07:10 PM

Quote:

Originally Posted by profdant139

Chris!! I did not even realize that was your post -- welcome back to the Club! Thanks for the kind words!

I think that there are charts on the Web for cable sizes, depending on the length of the run. Whatever size you choose, someone will always say "not big enough!"

And have you thought about a diagonal brace or truss under the back battery shelf? The real enemy is vibration, causing the metal to flex and crystallize.

One more issue -- by extending the back, might you risk bottoming out when leaving a steep driveway? If you already have a lot of "escape angle" clearance, this will not be a problem.

Dan, the 230 sits high up off the ground. I am thinking about a shelf that is not an extended carrier type but rather a bumper reinforcement to build a lengthwise battery box.

Right on with the cable width. Just like tow vehicle and solar panel size, bigger is never enough. Thanks for the advice.

gmw photographics · 12-18-2015, 05:38 PM

I'm gonna be the odd man out here, and suggest something different. And that would be to place the weight of the batteries near, or over the axles. If they are flooded cell, they will need to be installed or vented outside the camper. Is it possible to fabricate your new battery holders "under" the trailer near the axles.
I am not a fan of putting heavy items at the back of the trailer. Doing so "can" potentially contribute to sway problems.
If budget is not an issue, switching to lithium batteries, and placing them for instance under a galley cabinet ( over the axles ).
Food for thought.

qtla9111 · 12-18-2015, 06:01 PM

Quote:

Originally Posted by gmw photographics

I'm gonna be the odd man out here, and suggest something different. And that would be to place the weight of the batteries near, or over the axles. If they are flooded cell, they will need to be installed or vented outside the camper. Is it possible to fabricate your new battery holders "under" the trailer near the axles.
I am not a fan of putting heavy items at the back of the trailer. Doing so "can" potentially contribute to sway problems.
If budget is not an issue, switching to lithium batteries, and placing them for instance under a galley cabinet ( over the axles ).
Food for thought.

I didn´t even think about that. I will investigate the possibility. I had wanted to put several things underneath such as horizontal LP tanks and sliding drawers.

I will look into the box underneath and near the axle. Thanks again for the suggestion

looking4fun · 01-01-2016, 08:50 AM

I have one battery in the back (oem location) and I added 2 batteries to the tounge. To run the wiring I used 10 gauge wire. Positive wire ran back to the a/c panel and ground wire was grounded right at the frame by the batteries. Haven't had any problems with the 10 gauge wire.

qtla9111 · 01-01-2016, 12:37 PM

Quote:

Originally Posted by looking4fun

I have one battery in the back (oem location) and I added 2 batteries to the tounge. To run the wiring I used 10 gauge wire. Positive wire ran back to the a/c panel and ground wire was grounded right at the frame by the batteries. Haven't had any problems with the 10 gauge wire.

Thanks, I wasn´t sure what gauge to use. Much appreciated.

jbfunfinder · 01-28-2016, 09:35 PM

qtla9111- This reply may be too late...just haven't checked the forum lately. My post of 1-11-15 has photos of the battery rack I installed under my FF just forward of the tires. Just search using the word "solar" and you'll find it. This was part 1 of a multi-part series I posted regarding my solar installation. Might inspire you to consider something other than the rear bumper.

John_C · 01-28-2016, 10:22 PM

I may be late as well. When I purchased my trailer, it had one Grp-24, 12 vdc battery and two 20# propane bottles mounted on the tongue.

I replaced the single Grp-24 with two Grp-31, 12 vdc deep cycle batteries and kept the two 20# propane bottles on the tongue along with the new batteries

I just picked up a pair of lug-end battery cables (If my memory is correct, these were 4 ga.) that fit and wired these two batteries in parallel, similar to that illustrated...

qtla9111 · 01-29-2016, 06:11 AM

Quote:

Originally Posted by looking4fun

I have one battery in the back (oem location) and I added 2 batteries to the tounge. To run the wiring I used 10 gauge wire. Positive wire ran back to the a/c panel and ground wire was grounded right at the frame by the batteries. Haven't had any problems with the 10 gauge wire.

That's good news. I have heard many different opinions but not from someone who has done it.

Thanks

TCP · 01-29-2016, 07:05 AM

I have the normal group 24 battery on the tongue, but added two 70 amp AGM sealed batteries under the kitchen sink, over the axles. The space just had some electrical wiring and pex plumbing pipes that I tidied up to make space. 6gauge welding wire ties them into the system at the converter, which is also an updated 55amp smart converter. I don't remember ever having run out of batteries, even after camping without hookups for 5-7 days at provincial campgrounds.