If I was mounting a typical diamond plated battery box like this across my two front trailer tongues I would use round head "stove" type bolts inserted from the bottom on the tongue with the washers and bolt nut on the inside of the box.
![](http://i1279.photobucket.com/albums/y533/bigcitypopo/649409657_tp_zpse9ba31e3.jpg)
I would also pick a box with a side mount latch with key verses a bolt clasp for using a padlock...
These two ideas alone would add several minutes to a thief trying to steal or get into your locked battery box.
I would mount some plastic risers in the bottom of the metal box to raise the batteries up off the bottom of the metal boxes where I could install a couple of fluid drain holes to drain directly to the ground. I will also spray a heavy coating of rubberized paint on the inside of the battery box especially the floor area. I will also install some strap hold-down idea for securing the batteries after they have been mounted inside the metal box. I am in rough terrain alot and could easily bounce my batteries and maybe short out the terminals on the inside lid area.
I also have had great success on using the PVC FLEX conduit and PVC Electrical Boxes with water tight lids to gain access to the metal boxes routing in the battery cables etc... The game plan would be no visible battery cables etc...
I also like this idea of a metal box with the forward tray where you can use for routing cables around the batteries and also is a great location to install battery vent tabs. This install uses a sink drain from LOWES for battery vents. The forward lip area would be a great location to install the BLUE SEA 4-position BATTERY SWITCHES I love to use.
![](http://i415.photobucket.com/albums/pp233/gilldawg79/IMG_0802.jpg)
This is my current battery bank installed across my front trailer tongue frame using standard plastic individual battery boxes. My future battery upgrade to replace my 2008 standard issue Interstate GP24's will most definitely use a metal box enclosure as battery thief in this area is really becoming common place these days.
Just some of my thoughts for my future battery box install on my OFF-ROAD POPUP trailer.
Roy Ken