DIY EBike Battery System

Description

In an effort to save costs for EBike batteries, we created a battery system that utilizes 40V RYOBI power tool batteries to power an EBike. We used a combination of 3D printed and COTS parts to make the mounts and wiring harnesses. Our system involves two batteries, connected to the motor in parallel via a Y-harness. Each battery is mounted to the bike on the mounts we designed, and an internal wire harness routes power to the Y-harness.

Check out our video here: https://youtu.be/FgjxSFlo72g
And our files and written documentation here: https://github.com/pittxprojects/ebike

Student contributors include Maya Román, Jack Rozzo, Peter DeNicola, and Nick Bohn.

Files

Battery Mount Base - Thick.f3z f3z - 1.57 MB - 05/30/2021 at 20:02		Download
Mount Assembly - Thin v3.f3z f3z - 5.88 MB - 05/30/2021 at 20:02		Download
Mount Assembly - Thick v6.f3z f3z - 6.17 MB - 05/30/2021 at 20:02		Download
Power Timer Contact 3D Model.f3d f3d - 2.96 MB - 05/30/2021 at 20:02		Download
Battery Mount Base - Thin.f3z f3z - 1.28 MB - 05/30/2021 at 20:02		Download

View all 11 files

Discussions

Charlie Lindahl wrote 06/07/2021 at 16:25

Where's the BOM? Specifically, the motor?

The GITHUB documentation MENTIONS the BOM, but does not provide it. I'm interested in finding out how to obtain the motor, and then I can either try to install myself or, as the notes suggest, go to a bike shop to help in the installation.

I can do the 3D printing of the battery mounts and also the wiring.

Assuming I can get the project working I could add power monitoring/logging to measure performance and maybe crowdsource results with other makers.

Charlie in Houston, TX

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Charlie Lindahl wrote 06/07/2021 at 16:39

SOME answers to my own question (google search on "mid-drive bike motors" :

BAFANG Electric Bicycle Conversion Kit ($899)
https://www.amazon.com/Bafang-Lastest-Electric-Bicycle-Conversion/dp/B01FX7GL1Q

And

Luna Cycles Kits
https://lunacycle.com/mid-drive-kits/

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Charlie Lindahl wrote 06/07/2021 at 16:45

BEST answer so far, article at ELECTRICBIKE.COM

26 Mid Drive Kits for DIY Electric Bikes
https://www.electricbike.com/mid-drive-kits/

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Scott wrote 06/07/2021 at 12:20

Looks like an awesome project! Out of curiosity, what is the max speed the bike can reach and for how long? Keep up the great work!

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adam.klotblixt wrote 06/01/2021 at 04:48

A very nice project. I just wish batteries here in Sweden were cheap enough to utilize this way. Had a look online and 2 of those batteries would cost roughly 3600sek which is in the same region as a cheap e-bike battery of >10Ah.
What happens when 2 batteries are inserted if they have uneven charge/voltage? Does the internal BMS:es even the voltages out safely, or is there an unsafe "fast charge" of the battery with lower voltage?

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DIY EBike Battery System

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Description

Files

Battery Mount Base - Thick.f3z

Mount Assembly - Thin v3.f3z

Mount Assembly - Thick v6.f3z

Power Timer Contact 3D Model.f3d

Battery Mount Base - Thin.f3z

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