Cell level fusing

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Oberfail

Member
Joined
Jun 22, 2021
Messages
61
Hey guys,

today I fell down the stairs with my first DIY battery and sadly some of the fuses i used snapped and i decided to redo the whole battery since there are many issues i have with it to begin with.

So my question is, how, if at all, you guys are doing your cell level fusing of 18650 cells and if any of you have encounterd any issues with your methode so far.

Greetings - Oberfail
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,746
I solder (as apposed to spot-weld) 30awg ( https://www.amazon.com/gp/product/B01M0AXONC/ref=ppx_yo_dt_b_search_asin_title) between the cell + and buss-bar and I use 26awg on negative side ( https://www.amazon.com/gp/product/B000IJYRQ6/ref=ppx_yo_dt_b_search_asin_title ). I dab the cells with solder (quickly) and then go back and re-heat to attach wire / string the wire back and forth with quick solders off the roll. Then use wire snips to cut the excess so there's only a single path from each cell to the bus bar. This technique minimized heat on the cell.

If you're spot welding, you can get nickel fuse strips - https://batteryhookup.com/collectio...uous-roll-by-the-foot-18650-cell-level-fusing - with fusing as part of the strip.

Highly recommended you fuse each 18650 cell - 1 side is enough, + side is the common choice!
 
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jdeadman

Member
Joined
Mar 28, 2017
Messages
948
I use 36 awg tinned copper on both sides of the cell (18650) and I connect them to a 3 strand 14awg solid copper strands wound together. to connect them together I use 63/37 solder
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,746
Can you also please tell me, which solder you are using @OffGridInTheCity ?
I use Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy https://www.amazon.com/gp/product/B07FLN3D6B/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 with 100w Iron - https://www.amazon.com/gp/product/B002I7X7ZS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

This solder self-tins and does not corrode over the years on the cells. My oldest packs are 3 yrs now and solder is fine - no corrosion. I don't think you need to buy "Kester" particularly - its the % mix "63/37 Alloy" that's key.
 

Oberfail

Member
Joined
Jun 22, 2021
Messages
61
its the % mix "63/37 Alloy" that's key.
Yeah thats what i'm looking into. 1kg 50€ of 60/40.
However, i'm still on the hunt for super thin tinned copper wires. The smallest i've found so far is 32awg, but i want to go down to 36 and possible even smaller in the future. I'm living in germany, so if anyone has a clue where to get some it would be appreciated a lot.
 
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