Thursday, January 12, 2017

Harvesting 18650 Cells from "Dead" Laptop Batteries

I have been using Hobbyking's "Multistar High Capacity 4S 8000mAh" batteries on my ebike for exactly three months and now it gets noticeably physically swelled.

The runtime has halved from what it used to and not to mention that it becomes more sensitive to ambient temperature.

I use my ebike to commute to work, so, a reliable transportation is a necessity for me.

Instead of buying another battery from Hobbyking, I figured, why not just try to use recycled 18650 cells from ebay?

The seller claimed that the batteries are from some genuine manufacturers that have passed its toleratable capacity loss.

This post is intended as a log on my progress for this project.

Well packaged by the seller (bargainretailer1). I got it for £68 in the UK. I am sure I can find a better deal if I tried hard enough.

20 units of AS10D51 batteries exposed.

It was rated at 10.8V @ 4.2Ah in its previous life.

First harvest! :)

All 120 pieces of 18650 Li-ion cells successfully extracted.

Simple resistive load test reveals 68 out of 120 cells were usable. Not sure if the other half can be recovered, so, maybe an update for a future post? ;)

Wednesday, January 4, 2017

3D Printed LiPo Battery Box for My Ebike

Visit my Thingiverse repo to view the STL files:

-I printed this in Excelvan Coffee and Red ABS filaments
-I use E3D Volcano (clone) to speed up print time, so, each part takes less than 90 minutes to print.
-Designed in 123D Design.
-The box was intended to be mounted on top of the bike frame.
-Able to hold three 4S 8000mAh lipo and ten 18650 cells.
-Took almost 1kg of ABS plastic
-Parts are glued using acetone and super glue (parts named bracket)
-Printer used was Wanhao Duplicator i3 aka Di3
-Connections made by using XT60 and XT90 connectors
-DB25 was used as balancing port
-The box is secured in XYZ-axis
-The Z-axis was secured using Nut Job:

This was the old box, Rev1.

Printed bottom pieces with its brackets.

Aligning it before glueing.

Mounting bracket using super glue as "tack weld".

Waiting for the super glue to dry.

Tack the other half.

Ready to be acetone-welded.

Close-up of parts interface before acetone-weld.

Another close-up.

Bottom view.

Bottom close-up.

Using plastic tube from q-tip to spread the acetone.

First weld, woot woot!

Welded interface side close-up.

Welded interface centre close-up.

Outside view.

Added another bracket (simple rectangle) to reinforce the joint.

The only part of the box that needs support.

Not impressed with the surface finish. :(

Trying to place the batteries inside, hey, it fits! :)

Both top and bottom fits nicely. The DB25 is for voltage balancing.

How the ABS melted? In first minute, it appears white.

After 10 minutes, the white turns transparent.

Now, I have to disassemble my old battery. (Got from a friend, thank you Zhang!)

Looks good to me.

The only bike mount that needs support.

Side view of the bracket.

Fits nicely to the box.

Another bike mount.

Installed on my ebike.

The box now contains 14S battery. I plan to add some switching power regulator for other accessories.
It is not the prettiest project in the world, but hey, it works.
Next project would be to build a cell voltage balancer. ;)