Full suspension BBSHD Trek Build

[DrunkWeldingCompany]

I have always wanted a full suspension ebike. Looking at the prices here in Norway I soon decided to build one myself. Started off with buying this used Trek EX9 2010 model.

I was thinking this would be easy. I soon discovered that this bike not was the easiest converting with the small triangle frame and the shimano pressfit bb71 bottom bracket. Started off designing a battery that would work for the bike. Finally made something work. My next post will be on this subject.

 

[DrunkWeldingCompany]

To run BBHD at around 1000W I decided to go for a 13S5P configuration using salvaged LG MH1 3200mAh cells. This would give me an OK capasity of around 15Ah. The cells are also rated for 10A max, therefore they should easily handle the 20-30 Amps the controller would pull at 48V. The first problem I encountered was finding a box (or premade battery) that would fit the small triangle with the suspension taking away a fifth of the area. I soon gave up and dusted off up my old Freecad skills. Ended up with theese:



I am posting the STL-files on thingiverse. Just havent got around to it yet. Send me a pm if you want the .STL or the Freecad files if you would like to print one or edit it yourself.

 

[DrunkWeldingCompany]

Got it pieced together. Pretty pleased with it so far. Still waiting for the 0.2x8mm nickel strips from ebay to complete it. Really hope they dont turn out to be nickel plated steel.


Also bought this BMS:
https://www.ebay.com/itm/254484111612
Anyone has any experiences with theese? I know the price is a bit on the low side to get good quality, but Ill just cross my fingers and hope it doesnt trash my battery. Guess well see soon

 

[DrunkWeldingCompany]

Finally got the box uploaded to thingiverse if anyone wants it.
https://www.thingiverse.com/thing:5205983

Having some problems with the alignment of the chain and the general fit with the adapter for the bottom bracket. Ill make a post about it tomorrow.

 

[DrunkWeldingCompany]

Found this template for the BBSHD from ebike essentials:
https://cdn.shopify.com/s/files/1/0...tout_74_100_Ebike_Essentials.pdf?v=1619116147
I have some questions I hope one of you guys can fill me in on: Are there really 2 different offsets as the template shows between different chainrings? I have to go for the inner one to make up for seemingly bad alignment. Does this mean I cant go for anything smaller than the inner 42T? Guess I also need to shave off some metal from the bottom bracket as I have about 10mm of play before I hit the chainstay.

 

[DrunkWeldingCompany]

Got around to mounting the battery box today. I used one of the original rivnuts for the bottle bracket and added two more into the frame. Next I secured it to the frame using a flat aluminium bar with three countersunk bolts. There is also a hole in the top of the casing for a strap or zip tie to the top bar. This ended up being really rigid and solid. Dont think I will have any problems with it coming loose. Fingers crossed

 

[LewTwo]

Neat job on the battery box. What type of filament did you use to print it?

 

[DrunkWeldingCompany]

Thanks. I printed it in PLA. My only possible concern is temperature. Pulling 30Amps from the battery in the summertime, the temperature might be a problem as PLA turn soft at about 80-100Celsius, but I think it will be ok. If this turns out to be a problem, Ill just print it again in PETG. Used PETG for the lid, but had some issues with warping when printing the box, so ended up using PLA for it.

 

[LewTwo]

PLA was intended to be biodegradable. It will eventually deteriorate ... but must faster if exposed to UV (aka the sun). You might want to spray is with with something that is UV resistant (urethane spar varnish for example).

 

[DrunkWeldingCompany]

Thanks for the tip. I will try to get the printer better tuned so that I can print it in PETG. I also see that PLA degrades when exposed to rapid changing temperatures, so printing in PETG will be a priority.