Please advise me on a homemade motorcycle

[Hummina Shadeeba]

I spun a standard out runner motor (Leopard 80mm) at 13,500 erpm (not so fast) and dipped it in the middle of a crescent of cells within millimeters, or sometimes touching, and barely an increase in current draw happened.


But I give up on the mid-drive with belts and realized I wouldn’t be able to get a big pulley on the rear wheel as the belt will hit the stays unless it’s a small pulley. I had planned for the other pulley to be in the main bike triangle and that’s the problem. If not able to get a big gear ratio with a mid-drive for increased power to weight/volume there’s no point. That was the main point.

I’m going to still pot a bunch of cells with bolts in the potting and bolt it around the downtube to an aluminum plate. The point being to mount the battery in a simple slick fashion. There’s not much material around the bolts but I’ll be adding fiberglass around there and a couple long strands of Kevlar. And I’ll also paint some softer polyurethane on the plate and battery where they meet the bike downtube

https://imgur.com/a/K7BmZTj

And just use a simple hub motor.

 

[Hummina Shadeeba]

https://imgur.com/a/6Svy2yK

What you think will happen with this potted (98) 26650 cells? There’s not much resin. Getting the shape cut in abs for 160$ w shipping, then make the mold from that.

These are standard steel torque arms I’ve been using for horizontal dropouts and here updated I’m getting more like this drilled and thinned.
and a shim/torque arm to mount a standard 10mm hubmotor axle into the common 14mm bmx dropout.



Bending a 26” wheel bmx frame from 110 to 135mm should be no problem and this was 24”. It has pretty symmetrical stays and expanded evenly. Oil is good.

But maybe the bmx frames having such steep headtube angles it’ll be hard to find a fork with a big enough rake to not be twitchy when going fast. I got a manitou suspension, so still small rake, but for 26” wheels so should give some angle. But don’t all the suspension forks give a bit of rise compared to a typical rigid fork of the same size? I have the green 26” bmx bike lined up. Almost the only available in USA right now. They all sold out w the pandemic u know.

 

[John in CR]

What you think will happen with this potted (98) 26650 cells? There’s not much resin. Getting the shape cut in abs for 160$ w shipping, then make the mold from that.

Instead of potting and then mounting to the bike what I did for a friend was fiberglass the 2 sub-packs directly to the frame. Then I sealed it up very well using a 2nd wrap of fiberglass. I used bondo to fair it into the frame, and spray painted it with automotive primer and paint for a completely water resistant 74V 22ah pack. I used some Chinese 15A rated cells that I had for a year and were all still in perfect balance at the voltage I received them in 1s7p tab welded blocks, and after 2 years of use with a 4.05V top of charge cutoff and 30A current limit they remain +/- .01V balance and show very little capacity degradation. The only thing I didn't like about the result is how the blue paint turned quite purple as it dried.

 

[Hummina Shadeeba]

Works. Till it doesn’t work and you have to cut it off though
I ordered ten 14mm to 10mm adapters/torque arms
If anyone is interested in putting a hub on a bmx bike. Cost me 19.50 each before shipping and you need two. Not cheap. The plain torque arms cost half as much

https://imgur.com/a/6Svy2yK

 

[Balmorhea]

Works. Till it doesn’t work and you have to cut it off though

Sorry of like a potted battery works until one cell or the BMS goes bad.

That's certainly what occurred to me when I saw Luna's potted packs. Given that I've bought two packs from them and had to repair both of them more than once.

 

[Hummina Shadeeba]

I’ll balance externally at least.

I never hear of people replacing bum cells. I’ll have to put the cells individually to some load and make sure they’re good before potting. But maybe your packs could’ve been problem-free it they’d been potted. It seems a great solution to vibrations and physical abuse


I’ll be able to take the battery off the frame at least. I guess you plan to cut it off with it being straight glued on?

You have any pics of ur method for that battery?