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DIY Lithium battery project(s)

widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
As I couldn't find a thread about I figured I would start a thread about it.

For the past few weeks I've been working on my first DIY Lithium battery project using 18650 cells from Samsung.

I have a old Chinese e-scooter which had 4 12V 40Ah batteries and after they died I decided to replace them with a DIY battery using Lithium.

After watching hours of Youtube, reading many articles on the internet I started the task to build:

- 2,5kWh battery using 210 Samsung INR18650-35E 3500mAh cells
- Kelly Controller KLS6018S controller
- Energus Tiny BMS s516 150A Battery Management System
- Malectronics Arduino Spot welder

Other things like SB50 connectors, Nikkel and 18650 battery cell holders I got from AliExpress and other local suppliers.

The goal is to have the e-scooter have a range of ~80km with a top-speed of 35km/h.

I'm starting this topic to share information and hopefully inspire other people to build their own batteries for all kinds of applications.

Once my project is finished I'll write a more detailed blogpost with a parts list and where I got them from.

A people usually like pictures I've got a bunch of them while the project is still under way.

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widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
Awesome! Keep us posted with your progress. Looks pretty good so far. The BMS looks especially great.
I will! The BMS is really great and professional. Developed by a company in Latvia and they seem to know what they are doing.

You can find cheaper ones on AliExpress or eBay, but they usually do a shitty job.

The benefit with this BMS is that using a external relay and current sensor it can handle up to 750A of current.

I'm working on a blogpost where I go over the battery itself and the BMS before going into the scooter's config.
 
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widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
@widodh I like this project. What the configuration of the pack? Assuming 48v motor in scooter
Tnx! I would love to see other projects here :)

In this case it’s a 14S15P pack, 58,8V maximum.

The motor is a 3-phase 2,5kW motor which is the original one.

I tweaked the motor controller a bit today and the top speed is now 40km/h and goes there in about 6 seconds.
 

Drewflux

Member
Aug 25, 2015
272
97
Australia
Are you up to something sneaky on the uart port of the bms yet? I wonder whats hiding in there. Also I noticed your spot welder in the pics, whats in the second case on the positive lead of the battery? Capacitor?
 

widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
Are you up to something sneaky on the uart port of the bms yet? I wonder whats hiding in there. Also I noticed your spot welder in the pics, whats in the second case on the positive lead of the battery? Capacitor?
No, I haven't checked the UART yet. But Energus tells us that they also send out ModBus information from the BMS. It's all in the datasheet of the BMS.

The connection on the positive side is a 300A fuse, in case all shortcircuits the fuse will blow. Just safety.
 

widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
My scooter is running again, I'll be working on a blog tomorrow with all the information.

With some spare cells I had left I build my own 12V 17Ah powerbank with USB outlets I got from AliExpress. It also has a regular 12V socket so I can plug in any 12V device.

IMG_0642-1024x768.jpg
 

Brando

Active Member
Sep 27, 2016
2,998
2,243
Bainbridge Island, WA
Here are some great details about 18650 cells - especially how to work with safely. (avoiding overheating and fires)

I did scan your blogpost
Building a Lithium battery for my electric scooter – Widodh

and I'm guessing this article might be helpful to DIY 18650 pack builders
Perhaps this info was in the book you used?? [Micah Toll - DYI Lithium Batteries]

What’s inside an 18650 cell? And why its important

@widodh
As I have no actual experience in building packs, your thoughts on the above article I'm sure would be appreciated by all.

thanks for sharing.
 

scaesare

Well-Known Member
Mar 14, 2013
8,569
15,059
NoVA
Great project!

Pretty amazing that a Li-ion pack that's less than 1/4 the weight of the original has nearly 40% more capacity.
 

widodh

Model S 85 and 100D
Jan 23, 2011
6,853
2,805
Venlo, NL
Here are some great details about 18650 cells - especially how to work with safely. (avoiding overheating and fires)

I did scan your blogpost
Building a Lithium battery for my electric scooter – Widodh

and I'm guessing this article might be helpful to DIY 18650 pack builders
Perhaps this info was in the book you used?? [Micah Toll - DYI Lithium Batteries]

What’s inside an 18650 cell? And why its important

@widodh
As I have no actual experience in building packs, your thoughts on the above article I'm sure would be appreciated by all.

thanks for sharing.
I'll look into that! Thanks for sharing :)

Great project!

Pretty amazing that a Li-ion pack that's less than 1/4 the weight of the original has nearly 40% more capacity.
Yes, it is. The weight reduction is also very noticeable. It handles a lot better. Sure, it's no Tesla acceleration, it's just a simple e-scooter which has a top speed of 30km/h, but it's a very practical and cheap way of transportation.

Although I usually take the bicycle for most things near my house.

Great blog widodh. Looking forward to hear more about the controller and other mods to the scooter
Working on that. The controller isn't tuned to my preference yet, a few things I still need to fix.

After that's done I'll write the post.


I would love to see other DIY projects here!
 

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