In this instructable, I build a 18650 lithium battery without a spot welder.

I included a video which might explain better (especially visually) all the steps.

Material and tools used:

Soldering Station (Hakko, not in the video but nonetheless my favorite):

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- Canadian Link: https://amzn.to/35rnFBX

Solder wire:

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Imax B6 Charger:

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- Canadian Link: https://amzn.to/2K3QYTQ

Alternative to Imax B6 --->Good quality RC charger (recommended):

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- Canadian Link: https://amzn.to/35pBuRg

Flux:

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- Canadian Link: https://amzn.to/3nvHv5p

2.5 mm Solid Core copper wire.

I had the wire in my scrap pile but you can find this at electric material supply stores and sometimes at hardware stores.

18650 Cells:

I used new Sony VTC6 cells (3000 mAh), bought from a reputable seller.

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Step 1: Place the Cells Into the Holder

Place the cells into the holder. I had a nice cell holder that came with the battery box I ordered.

If you don't have holder you can glue the cells together using hot glue.

Pay attention to the battery configuration at this point (in my case 7s6p).

Step 2: Check Voltages and Start Cutting the Copper Wire

I should have checked the cells voltages at the previous step but all the cells were at the same voltage.

Now it's time to cut the copper wire according to the configuration of the battery. Make sure you don't miss any cells and don't cause any shorts.

Step 3: Start Soldering the Copper Wire to the Cells

I placed some flux on the cells before soldering.

With the soldering iron set at 425-450 Celsius (800-850 F), I started soldering the cells and the copper wire. The trick here is to use high temperature with a low contact time on the cells in order to cause the minimal heat damage.

Step 4: Check Voltages Again and Charge the Battery

Once the battery is all soldered and complete, you can check the voltages again (they should all be the same) and use an RC charger to charge/balance charge the battery.

I hope you enjoyed this instructable!

I've build several batteries this way and 1+ year after I saw no sign of degradation yet. These batteries are used in electric bicycles.