Lengthening battery boxes

[John Langford]

Since I just asked a question, maybe I can compensate by providing some useful information.

My original 4D house batteries recently failed after 9 years and when I did the measurements for new deep cycle 4Ds or 4 6 volt golf cart batteries, I found that the lovely original equipment fibreglass battery boxes were too short for either option. So I  lengthened them to accommodate the new batteries but still fit into the space under the starboard saloon bench of my MK II.

To lengthen them I first made a male mold of the inside of one of the box using wax paper and expanding foam. I then ground down a 6 inch area midway along each box and cut them both in half. I put the mold inside the first box with a flexible layer of plastic sheeting (to keep the heat of the resin kicking off from melting the mold) and a new layer of wax paper, adjusted the length of the two box sections to the desired new length and laid up about five layers of roving and mat. Repeat the process with the mold and the second box, do a bit of tidying up with a grinder when the glassing has kicked off and you now have two longer boxes.

The two pairs of Trojan 105s are like a miracle after nursing the commercial 4Ds along for the last couple of years. I strongly recommend this upgrade.

[Roc]

John,
I would assume that you fit the two golf carts to be snug lengthwise, but what about in the width?  I think the OEM boxes are wider than the width of a golf cart battery.  How did you secure them all down?  The OEM 2x4 that fits over the two 4D's won't work with the 4 golf cart batteries.  I installed 4 golf cart batteries,  but I took out the fiberglass trays and used 4 gp 24 battery boxes. The golf carts will fit into the gp 24 box.  I bolted the boxes down (much like how the fiberglass boxes were attached).  I would like to know how you secured your Trojan golf cart batterys down since I'm in the process of fabricating something for my installation.

Thanks

[Ken Juul]

Nice explaination, but pictures and a write up for the wiki would be better.  Be happy to help with the wiki part if your not ready for that challange.

[John Langford]

I will try to get some photos and provide more detail. The wiki shouldn't be a problem. Time is the problem as I am still a working stiff.

As to fit, I adhered in my own way to the width rule (the container should be no more than 1" wider than the battery) by filling the extra space in each box with a slightly modified piece of 2x4. The batteries cannot move sideways in any direction. I then repositioned the original retaining bar and its U-shaped attachment pieces over the central junction of the four T105s so that another 12" piece of 2x4 could be placed under the bar perpendicular to it and screwed to it. This "cross" arrangement effectively traps all 4 batteries in the event of a knock down and still allows access to all of the fluid caps on the batteries. Of course, I rescrewed the enlarged boxes into the floor of the battery box area as per the original arrangement.

let me know, in the absence of a photo, if that is not clear.

[Roger Blake]

Had the same problem and took a shortcut...cut the boxes in half, feathered the cuts back about 3", set the halves to the correct length, fiberglassed the space (tying back into the feather part), sanded smooth. No problem since 2005. My tiedown system works, but needs improvement...now, on to those pesky leaks...