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Boulder, CO

A guide to the wilderness of the West.


Auxillary Batteries

Derek Bartz

What Batteries to Buy?

Tons of options here, but I only considered AGM sealed batteries.  They can be mounted in any position, don't off-gas, and don't require any maintenance.  How many amp hours (AH) do I need?  I want as many as possible, without breaking the bank or loosing too much space in the van.  I decided on two 6V 225AH batteries that I will wire in series, which will give me 225AH at 12V.  This is about the minimum AH that I was willing to go with, but I am always able to add more capacity further down the road if need be.  Just like last time, I bought the VMAXTANKS batteries off of Amazon (somehow Amazon is able to ship these to you within a week of purchase for FREE).  These treated me well in the Econoline and seem to get good reviews with all the other RV'ers online.  I went with two 6V batteries as opposed to 12V based on information I had read on a couple sites stating that they are better suited for a deep cycling solar power setup; and the 6V batteries are more compact...which is nice.

Where to put the batteries?

When I first bought the van I had gotten the idea to mount the auxillary batteries underneath from Dakota over at traipsingabout.  I took the PM to a local shop to get a quote for the job and was told it would be minimum $1000 to mount two 6V batteries (just for labor, not including the batteries); not a price I was willing to pay.  Ok, figuring out how to strap two 70lb bowling balls under the van can't be that hard right?  I procrastinated on the project, toying with designs in my head; until I finally convinced myself it could be done.  Having no experience with metal work and fabrication, I contacted Iron Rose Forge & Welding LTD here in Boulder.  Amos does fantastic work and quickly corrected my initial design to make things simple yet bomber. 

Reworking the design

Iron Rose Forge & Welding LTD

The Design

I initially wanted to create a box that would house each battery, and then fabricate brackets that would screw into the chassis to hold them up.  Not going to happen with my skill set.  Amos recommended a simple design using two straight metal bars and four bars of all thread and pressing the batteries between the bottom of the van and the bars.  He assured me it would be plenty strong and it worked.  This was also a fast and cheap solution.  The metal and all thread were $30 and Amos charged his hourly rate for the labor, 40 minutes for $30.  

I picked up this mat to use as padding between the van/brackets and batteries...

and cut it to size

Same for the bottom

Simple but thing I forgot to do is spray paint the metal brackets to protect them from rust.  I plan to take them off at some point and do so.

The Install

I wanted to install the batteries on the drivers side of the van to even out the weight of the van a bit; the kitchen will go all along the passenger side wall and the weight of the cabinets will add up.  There was really only one spot underneath the van that would fit the two batteries remotely close side by side; right in between the brake line and exhaust pipe.  This wasn't quite as off-center as I would have liked.  Losing clearance height was another thing I was worried about with the install, but the batteries don't hang any lower than the exhaust pipe so I didn't lose any with these types of batteries.  

I traced the pattern of the batteries and brackets.  I bench pressed the batteries up to the bottom of the van while Michele made the marks.  This was before I realized using a jack would be WAY easier.

I should have done this before installing the sub floor.  The blue tape line is a rough guess of where the couch/bed will be.  I plan to run the wire through the floor up underneath the bed and hook it to busbars.

All thread set, ready to mount the battery.

Luckily I had access to a nice lift/jack that I was able to help mount the battery with.