Materials for mid-frame enclosure?

[JennyB]

I have a shrink wrapped 18650 battery (36v 20ah) that I've be carrying in a saddlebag. Lately I'very experimented with a modified bottle cage mounting, which works well, but it could do with more protection for winter riding.

Here's the idea: a couple of rigid side plates (ply?) bigger all round than the battery, and through-bolted together through something softer like neoprene, so that it can securely rest on the down tube and up against the seat tube with only a single strap round it to hold it in place so that it can be quickly removed for charging.

Since it's going to be in a damp place (wet roads, possibly no front mudguard) how hard should I try to make it completely waterproof?

 

[dogman dan]

You might just look at this. I have one on my longtail bike, and it's really superb.

http://em3ev.com/store/index.php?route=product/product&path=43&product_id=125

Another option is to build you box with thin wooden top, bottom and ends. I have used 1/2" thick aspen or poplar wood for this very successfully. Then the sides are something thin, sheet aluminum, plastic, paneling, even coroplast like real estate and political yard signs.

The wood can then mount permanently to the bike, and the sides can be made relatively easy to remove to get at the battery.

 

[amberwolf]

Wood is probably the easiest stuff to seal up and work with for something like this. If you don't need it to last a super long time, (or you are willing to soak it in a wood sealant or lacquer it or something) you can use thin masonite for the side panels, and plain old white pine or whatever is handy for the "frame" that gets fixed to your bike frame tubing.

If I were to make a really quickie triangle frame for packs of something RC-LiPo-sized or smaller, I'd use 1x3's fastened (screwed and glued) into a triangle just smaller enough than my bike's triangle to fit snugly inside it, with recesses (countersunk screwholes) for the water bottle mounts.

Then I'd use fender washers and countersinkable screws (something with a thin head, at least) to secure the frame to the bottle mounts on at least one tube (and two tubes if you have two bottle mounts, like some bikes have one on top of the downtube and one on the front of the seattube).

Then I'd use hose clamps thru small slits (sealed with silicone later) to secure the top of this to the toptube.

Then I'd screw one masonite side panel to one side of the wood frame, with a permanent sealant between them (wood glue, most likely).

Then I'd make a gasket (old mousepads or thin exercise mats may work if they are dense closed-cell foam) for the other side of the frame and glue it on. Wait for that glue to dry, so it doesn't get all over stuff, or sponged into the foam and cover on the next step. You may want to make a notch in the bottommost corner of the gasket for wiring to exit/enter, just wide enough to allow the main wiring thickness to pass thru (the edges of wiring will compress the foam a little and help make a seal).

Then install batteries and wiring, and fill any empty space with blocks of leftover wood, and the least-compressible foam I could find (liek the rest of what you used for hte gasket, for instance), and run your main power (and/or charging) wires out the notch in the bottommost corner of the gasket.


Then screw the other masonite cover down over this.


Paint, if desired, and wait for it to dry before you ride it.




There's also lots of other ideas in this thread:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=12847


and here's a search on various battery case threads for a list of others:
http://www.endless-sphere.com/forums/search.php?keywords=battery+case&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

 

[dogman dan]

Yes, if you have the room for it, 1x4 stock is easy to work with and cheap. I have found softer hardwoods like poplar come in 1/2 thick, if another 1/2 inch of space is critical. Better wood than pine, with varnish, can last a very long time in the wet. Also quite possible to omit the thicker top piece. Lots of cheap ways to attach to the frame. I have often just cut strips of thin galvanized sheet metal and screwed it to the wood, wrapping it around the frame tube. Pad it if you are concerned about scratching the frame paint.

Another alternative material to wood, the thicker polyethylene cutting boards are about 1/2 inch thick.

Somewhere there is a recent thread where a guy just bent tabs on sheet aluminum, then used the tabs to epoxy the sides of his box in place. Turned out very nice. But personally, I don't mind the look of the screws, and do like the ability to pull off a side to mess with the battery or it's internal padding.