battery enclosure II

1.29.2011 – Saturday

After pancakes and breakfast sausages I set out to complete the battery enclosure. For the most part things went as planned. There were two minor hiccups; Dad and I had difficulty joining the copper pipes, and drilling a hole through the garage wall was, simply put, more than just drilling a hole.

The final part of constructing the enclosure was installing the ventilation pipe and doing the final fitting of the lid. The adjustable shovel bit that was being used decided at point to change size (smaller). With a hole cut completely through the garage wall, and sized differently at both ends, we had a problem. Luckily we had a hole saw bit also at the ready. The change in plans came when the hole on the outside wall had to be cut at 1-3/4″ instead of the intended 1-5/8″ that fit the pipe snuggly. Using the hole saw bit to widen a hole meant a piece of plywood with a precut hole had to be used as a jig. With the hole in, I could now work on the pipes (and return to the warm garage).

Assembling the pipes also saw its share of problems. Dad first attempted to use something called plumbers caulk – which required a bit of elbow grease because it first had to be kneaded like dough until warm. Then it was applied. Somehow, the step where it forms a tight seal and holds everything together got skipped. The pipes fell apart an hour after the procedure. Next up we tried a silicon based all-purpose glue and sheet metal screw. That did the trick, though it was not the most elegant solution. Four screws were used; one at each end of the pipes, and also at the elbow. Finally the pipe was mounted on the wall. The end still needs to be screened and (a task for warmer weather) the outside needs to be securely caulked into the log siding.

A view of the slot for the sides to sit in.

The small 3/4″ copper pipe ends just above the rubber mat, that large 1-1/2″ copper pipe ends at the top of the enclosure.

Two battery temperature sensors are held in place…

…so that a notch in the side of the enclosure lines up

The top of the battery box was fun. It was by far the easiest part of the project. Note the lip along two sides — this was done so that lighter than air hydrogen gas cannot escape along the two outside edges of the enclosure. Because the lid is not held on by any mechanical fasteners or latches, certain design elements needed to be used in order to encourage the hydrogen to vent only where desired.

Rounded edges make the top much easier to align with the battery cable bundles.

This lip is held on using pop rivets.

The system is looking pretty good. Covers for the bus bars are still in the preliminary planning phase. The box will eventually be painted — but I wanted to get some pictures before that time to better highlight the new construction.

Overall I’m satisfied with the final result. The batteries remain easily accessible for maintenance and visual inspection, but gain protection from dust as well as good ventilation for hydrogen. In addition to performance, the terminals are now inaccessible to small children, and the likelihood of accidentally bridging a positive and negative contact is greatly reduced.

While a clear top may be the top-of-the-line feature for a battery enclosure, this box was constructed using screw, pop rivets, and glue left over from other projects and an additional 80 dollars in copper and wood (~ 45 dollars for just the copper pipe and elbows).

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