There is an existing 'Jayco Mods' thread on adding a second 12V Marine/RV battery by "SmokerBill", so to keep our "volts" from getting crossed I thought I would post my 6V upgrade on a separate thread.
Since my boondocking has been increasing my battery amp/hr capacity has become more critical, especially since I have yet to invest in a solar system or a generator (leaning toward solar). I'm very conservative on my energy usage, and also incorporated LED's to minimize amp/hr draw.
After researching different deep cycle batteries, I decided to go with (2) Interstate 6V GC2-XHD-UTL Deep Cycle batteries. First I contacted Jayco to confirm that the existing support rails would hold the additional 100 pounds that the (2) 6V's would add over the (1) existing 12V Marine/RV battery. Next, finding (2) single 6V battery boxes that would fit into the existing space within the A-frame. Since I remove my batteries between camping trips, I didn't want to go with one battery box containing both batteries.
The inside dimension between the angle support rails on my 2005 Eagle is 7 1/2" which allows for a standard group 24 battery box width, and I had about 25 1/2" inside the A-frame. The other factor was that 6V deep cycle batteries are 1" to 1 1/4" taller than a standard 12V group 24 battery, so a standard group 24 battery box wouldn't be an ideal choice.
I did find a battery box manufactured by Power House A/T, #13228. I purchased two of them from http://www.rvplus.com/power-house-a-...ack-13228.html
, basically it's a modified group 24 box with an additional 1" in height. NOCO makes a box for the GC-2 (6V) deep cycle as well, but the manufacture told me that they are 7 3/4" wide...., won't fit between the Jayco support rails without some additional modifications.
Upon receiving the boxes I determined what battery orientation would best meet my existing cable paths, and I was also curious whether or not the battery box lids would be an issue (touching each other). I found that the Interstate batteries were about 1/4" taller than the new battery boxes, but the lid design did allow for a firm fit over the battery surface. Since I was using (2) 6V batteries, I had to wire them in series to produce a 12V output.......,
Once I confirmed my battery and lid orientation, I had to purchase a longer 4-gauge ground cable, and a 19" 1-gauge cable ((connect the (2) 6V batt's together)). I was also pleased that I was able to route all my cables/wires to the rear of the battery boxes. This is the end result..........,
I could have rotated one of the battery box lids 180 degrees creating more usable space between the boxes (or moving the boxes closer together), but then my cable/wire routing would be impacted and the 1-gauge cable would have to be lengthened (or cutting access into the lid for direct cable landing on the terminals).
I was able to create a little radius in the 1-gauge cable between the boxes allowing the lids to be placed as shown in the following photo. I also made the length of the 1-gauge cable as short as possible as well. With the battery box lids in place I ended up with about 1/2" between the lids. I also had about 1" between the one battery box and the inside wall of the A-frame allowing for cable/wire runs (E-brake switch, etc.). I did put tape over the lid vents feeling that there was plenty of ventilation through the cable openings. Plus I prefer to keep the moisture off the terminals.
Now I have 232 amp/hrs capacity
compared to about 65-80 amp/hrs with the 12V Marine/RV battery. Plus the 6V deep cycle batteries are designed to take a lot more discharge/charge cycles without degrading the battery capacity or life of the battery. Since it''s recommended not to discharge a battery to less than 50% capacity, my TriMetric battery monitoring system will let me know where I stand.
Please Note: Placing a 70lb battery into a plastic battery box can be a little tricky, especially when the battery doesn't have anything to grip on to. The tabs on top of the 6V battery are for golf cart hold-down brackets only and aren't designed to hold the weight of the 6V battery under lifting conditions. What I did was wrap and buckle the two new nylon straps (came with new battery boxes) around the battery, then had a friend steady the battery while I lifted the battery with the straps and lowered it into the box. Just unbuckle the straps and pull them out from the box. Don't use an old nylon strap, the sun and weather has compromised the integrity of the nylon.