Bigfoot Travel Trailer Battery upgrade:

The Upgrade Challenge:

• Increase battery capacity to 260 amp hours by installing two (2) Trojan 6 volt T-145 golf cart batteries.

Possible Solutions:

• Install batteries inside camper: The inside installation of batteries requires using valuable storage space, cutting ventilation holes and the purchase of expensive AGM batteries at a reduced amp hour rating over two wet cell golf cart batteries.

• Install optional plate behind 30 lb propane tanks: This would require the purchase of expensive AGM batteries or create difficulties in maintaining water levels in a traditional wet cell battery. This plate would also have to be mounted a few inches lower than the propane plate, lowering the clearance of trailer.

• Cut away factory propane and battery plates and start all over: This plan would require time in working out a better design and welding expense.
After I realized a better design was possible, I made the decision to start all over by removing the factory mounting plates, safety chain & ground lug. The safety chains will be reattached on the outside of the frame.

The disadvantages of my new design are:

• The two 30lb tanks had to be given up for two 20 lbs tanks; however the 20 lb tanks are easier to handle and 40 lbs of propane is more than enough propane for our outings. When it's not enough propane, it's easy enough to remove the first empty tank and get it filled, or just put an extra 20lb tank in the truck. Giving up the 30 lbs tanks was the key to making this work. The 20 lb tanks are shorter and can be moved back enough to allow room for two batteries.

• Four hours of a welder's time and about 10 hours of my time. I had the welder do the minimum. I filed all the metal edges smooth, cleaned, primed and painted the new work.

The advantages are:

• An increase of battery capacity from 80 amp hours to 260 amp hours
• A better battery with the Trojan 6 volt deep cycle batteries
• Easily accessible
• Increased trailer clearance over original factory mounted plates

I made several mock ups using cardboard and wooden platforms to make sure everything would fit and more importantly, that the propane tanks could easily be removed after the shroud was installed. I took the cardboard template, propane holder and battery box to the welder to make sure there were no communication problems.

Dimensions of the battery & propane plate:

Front 12 ¾ inches Back 36 ½ inches Sides 27 ¾ inches
Drop 4 ¼ inches (This is measured from bottom of frame to bottom of plate)
Plate thickness is 1/8 inch

Note: The drop is critical. Any less than 4 inches and it won't be possible to get propane cylinders out. At 4¼ inches, I have to remove the lid to the battery box (a 10 second job). Any more than a 4½ inch drop is just reducing the trailer to ground clearance.

Dimensions of battery box:

Outside 15¼w x 11d x 12¾h inches
Inside 14w x 10¼d x 12½h inches

Notes:

• An addition small front plate was installed flush with bottom of frame. It has a 2 inch rear lip. This makes a good place to toss the jack wheel (if you use a wheel, I don't), two 1 lb propane bottles, clips for equalizer or whatever.

• Holes were cut in the large bottom plate for straps that are used to secure battery box. In addition, a small lip was welded in the middle of bottom plate. Battery box fits between this lip and the frame.

• The battery box was purchased from the Trojan dealer. It is made for two Trojan 6 volt T105, T125 or T145 batteries. All three of these batteries have the same foot print. The T145 is taller and fits perfectly in the box. There was no manufactures name on the box, just a sticker that read Made in Canada. A very nice box that I highly recommend.

• A square channel was welded across the back of the plate for additional strength.

• The safety chains were moved to outside of the frame, with a better weld than the original. Be careful the outside location doesn't interfere with fiberglass shroud.

• The grounding bolt was cut off and a larger one installed in an optimum location for this new design.

• Like everything, it could be done better the second time. Overall though, I am very pleased. The batteries are very easy to maintain. Also, 20 lb tanks are easier to handle than 30 lb tanks. The older I get the more I will appreciate my switching to 20lb tanks.

Shown below are the pictures.

Click to view attachment Original design

Click to view attachment New plate cleaned and primed

Click to view attachment Painted and drying

Click to view attachment Side View

Click to view attachment Loaded up - Side View

Click to view attachment Loaded up - Top View

Click to view attachment Fiberglass Shroud in Place

Click to view attachment Finished

nice work, looks great

It does look good. It looks like you have lots of height, and 30 lb bottles are the same size diameter as 20 lb (at least the ones I have are). Just curious as to why you could not use the 30 lb bottles.

So the shorter tanks fit closer to the trailer due to the curve? No way it would all fit under the shroud with 30# tanks?

Oops, I kinda missed that.
Too busy looking at the pictures (still coulda seen it there)

Also, the Trojans weigh in at about 145 lbs for the pair, plus the added platform weight, minus the weight of the previous battery, so dropping 20 lbs of LP helps make up for that -- No point in carrying 60 lbs of LP if 40 is sufficient.

You are right about the weight of those two batteries (72 lbs each). So, I increased the battery weight by about 100 lbs and lost 20 plus lbs of propane. So, I am about 80 lbs heavier on the tongue. I should have at least listed this as a point and perhaps a disadvantage of this design. Since I am towing with a ¾ ton truck it wasn’t a disadvantage for me.

Dean

It may be an advantage for someone's rig that is already butt-heavy!