Custom battery pack advice...Thanks!

[BarkMau]

I’m dealing with a small triangle. It’d be nice to cram all the Whrs possible in it. Given its size, is it worth the trouble of making a custom pack for it or should I just go with a box on the fork…or both? Chances are, what can be fitted in the triangle won’t be significant and therefore not worth it. The total width of the triangle pack should be around 3”. So the questions are, what’d be the recommended chemistry for this pack. Kinda leaning towards Konion cells since I’m familiar with Makita batteries and how well they perform. Also, I understand Konion cells would outlast Lifepo and Lipo chemistries. How about performance wise? Finally, how much volts/amps should I expect from this pack.
Thanks a lot,

H

 

[e-beach]

You should be able to get 10ah - 15ah into that triangle depending on the battery chemistry you use. You won't have any room for the electronics.

3 inches wide might be a bit narrow, 4 inches wide would be more realistic.

What material were you going to use to build the box?

 

[Jason27]

I use a rear rack for batteries. It's a lot easier to remove than having a triangle set up. Jmo

 

[BarkMau]

You should be able to get 10ah - 15ah into that triangle depending on the battery chemistry you use. You won't have any room for the electronics.

3 inches wide might be a bit narrow, 4 inches wide would be more realistic.

What material were you going to use to build the box?

I think 4" is ok as long as it narrows down at the bottom to clear mid chainring. As far as materials for the box, I would consider fiber glass, plexi, or a plexiglass/duct tape combo which should be quick and easy to make.

 

[BarkMau]

I use a rear rack for batteries. It's a lot easier to remove than having a triangle set up. Jmo

Where do you have the motor? Mine is in the rear, that's why I'd like to avoid concentrating all the weight back there. Also disc brake isn't conventional rack friendly. I'm using a seatpost rack-not a good idea to load it with batteries. If I put batteries in the back, it would be a small ish pack right behind the seatpost. 24" wheel leaves more room. Also, plenty of anchoring spots there to do it properly but it would be a custom pack as well .

 

[dnmun]

above the top bar too, and behind the seatpost where the caliper cable normally runs since you have the disk brakes. the cells do not all have to be together in one big box. they can be spread out and you can use large size cable to connect the sections and use extensions on the sense wires to reach all the cells. the cells can get wet, that should not hurt them unless it is so much water they short. but the BMS will short out if it gets wet and shut down. so something structural but not air tight is ok. jmho

 

[motomech]

You under-estimate the usefullness of that space.
My opening is 16" X 17" X 10" and I can easily fit 15Ah of 12S in the bag and another 5Ah in the tube below.

I'm not saying the EV Falcon bag will work without bunching, but there is lot's a space there to work with.
P.S. I carried a gallon of milk in a bag on the frt. forks the other day and the handling was just awful, I don't get people putting batteries on the frt. forks at all.

 

[BarkMau]

I like the tube idea, could prolly do one along the top tube.
Motomech, what chemistry do you have in there? do you know of any tutorial on how to do it? What's your setup, front hub? 2wd?
A load on the fork must be secured tightly.
Thanks!

 

[motomech]

Check the build link below.

I used to be a heavy equipment mechanic and the tube came from a new John Deere tractor. The Owner's manual and other doc.s came in it.
2 Turnigy 6S, 5Ah, 20C Lipo bricks[my prefered battery these days] fit perfectly.

 

[e-beach]

As far as materials for the box, I would consider fiber glass, plexi, or a plexiglass/duct tape combo which should be quick and easy to make.

I did my frame out of wood. This is what it looks like at the moment. I have plans for improvement, but it will take a few more weeks until I have the time. It doesn't get too hot where I live and mostly ride, but it is probably best for the controller to be exposed to the wind.

As far as durability for this build, I was in a crash a couple of weeks ago where my back wheel flipped over my head.

My battery pack still works fine. I have them strapped in with plumbers tape dipped in Plasti-dip.

If you want to see how I made the frame check out the top part of this thread.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=39690

 

[BarkMau]

e-beach, good idea and great tutorial on the box build.
motomech, awesome thread on your build. Kudos!
Thanks y'all.
H