I moved in with the GF a couple weeks ago and unfortunately between packing and moving, I had to push the bike project aside for a bit. My buddy also had a huge project at work and couldn’t work on it either. Looks like it’s back to work this weekend and next to get things started up again.
I’d like to test my batteries a bit this next week on my spare time and do some IR matching/sorting. Also want to get some of the fiberglass drilled and sanded.
Starting to get more and more excited!
With the previous pack design (trapezoidal), it was a nice simple shape, but the pack mounted inside the frame a little weird and made it difficult to fit in the controller and charger. I started thinking, maybe it would be more simple to have the batteries in a sort of L shape around the motor. Since there’s ~10″ between the frame posts, I figured we can get 5 cells wide in a staggered configuration. The current would flow down one side, up the other and there would be 2 packs essentially. The lid would be simple and the mounting points for the pack would be near the corners/sides of the pack, which is great for strength.
I spent some of Weds with my buddy Travis (T2) kind of mocking it up and it looked like it fit. To make sure, I came back on Saturday and did a to-scale mockup of the pack with real dimensions. Just cardboard and tape this time (foam core was overcomplicated).
I fit it into the bike and it fit pretty well actually. It hits the tank right now on the sides, but there’s some extra space in the pack so I think it’ll fit perfect. The tank isn’t fitted with the front mount either, so it should raise a little off the frame. I think I want the pack to be just the batteries and leave the contactor and BMS outside. It’s just too hard to fit all that inside and make a nice lid for it. The controller fits right where the original radiator did, which is nice because it gets tons of airflow through the heat-sink Noah made. The charger can go right under the controller near the bottom of the pack. Even with the forks compressed, there’s about 5-6″ of horizontal clearance.
T2 and I decided that this will be the final pack style. Not only does it simplify mounting and increase structural strength, but it also makes it easier to fabricate the pack. It also leaves a ton of room under the seat for a box that contains the BMS, DC-DC and some other electrical components. We’ll be drafting the model in 3D this week and have the drawings to my buddy Dave for fabrication.
So Travis (T2) has been busy this last week drawing the batteries and buss-bar in 3D since I lack experience. It turned out great and gives the clearances between cells so that we can mill the cell-holders out of UHMW. This week he’ll start to draw the holders and add on the Elithion cell-boards to the drawing (Elithion provides these on their website).
Once we get the pack drawn in CAD, I want to mill these parts out of fiberboard (probably HDF) and check fitment. Then I’ll build up a pack without buss-bar and refit and start to figure out how we would like to do the metal box. I’d like to build the box around the HDF prototype so if anything has to change, I’m not wasting $200 worth of UHMW plastic.
Here is a picture:
I went to the shop last Thursday for a little bit and talked with Travis. I showed him the mockup and how well things seemed to fit inside the frame. We didn’t spend a ton of time on the bike that night, mostly just talked about the overall idea of what the project plan is.
I returned Saturday and cut the top area of the gas tank. This is where the original gas cap was. The pack as it is, just barely hits this on the inside of the tank. I figured we could cut it out and get another inch and fill it with fiberglass and epoxy later. I also cut some plastic out of the rear fender where the original battery holder for the 12V battery was located. There is a ton of room under the seat just above the rear shock and in front of the rear tire fender. I brought in my DeltaQ and it fits pretty much perfectly in that space now that the plastic is gone. I might have to modify the charger a bit, but It should fit in that space fairly well.
I compressed the front tire again and estimated how much room the front fender takes. I reinstalled the mockup, placed my charger, placed the controller and put the gas tank on. There a surprisinly large amount of room around the battery pack. The issue now, is how to design it such that the frame is properly supported, as the engine was a stressed member.
For now, Travis is going to help with some 3D CAD work and draw up the pack with the bussbar and BMS. Then hopefully we can get some pieces cut out of MDF that match the exact dimensions of the pack with all of it’s hardware. Until we really get that done, it’s just a rough estimate where things are at this point.
I’m not able to go this week (going out of town again), but Travis is going to do a little work and we’ll meet up next week and see where we’re at. That’s it for now, but things seem to be going along well.
I went down to the shop tonight to test-fit the battery pack mock-up. Since I oversized the pack, things seemed tight at first. Just to make sure everything fit OK, I used a tie-down and compressed the front forks as much as I could. This ensures that I’d have enough clearance under heavy braking. Add a little wiggle room for fork flex and fudge factor and things fit pretty well.
I put the side fairings and the Faux-tank back on and made sure it all fit. Even with all of the wiggle room I built into the mock-up, it fit just fine. There’s plenty of room for the charger inside and quite a bit of room underneath the pack for the controller and wiring.
It’s got a little bit of refinement left, but it’s a great start. I’ll be back down there tomorrow my buddy Travis to kind of finalize some things. Pretty happy with this setup.