26 AWG solid silver-plated OFHC copper wire as a fuse?

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JonCombat

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Jan 11, 2022
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I am looking for a reliable inexpensive fuse wire option for 18650 batteries (2500-2600 mAH). I I am working on my first 3s battery pack and would like to fuse each cell for safety. I have rolls of wire wrap and was wondering if I can use them for each cell. Any suggestions?
 

OffGridInTheCity

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Dec 15, 2018
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I use 30 awg for my fusing - https://www.amazon.com/gp/product/B01M0AXONC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 It burns thru from 7 - 20a (anecdotal experience). I've accidentally shorted 7s7p packs - and it works! and also a 1s100p pack - and it works!
Remember that fuse wire is not to protect individual cells - but rather the rest of the pack from a cell that goes bad -> to a dead short. It also protects against overall shorting of the battery .... BUT it's a lot of work to replace the fuse wire so best to avoid that :)

@hbpowerwall did some youtubes on shorting packs/ fuse wire :)
View: https://youtu.be/iL6Td8R5C1g


And @AveRage Joe has done several youtubes on fuse wire - just search "fuse wire" in his youtube search box. Here's one of them :)
View: https://youtu.be/jKKlpKd3TBk

View: https://youtu.be/iL6Td8R5C1g
 

Korishan

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Jan 7, 2017
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OffGridInTheCity brings some good videos. Both videos, and producers, are great tips and suggestions. Watch more of their of videos to get more in depth details.
Any wire you use as a fuse you need to test to verify that it blows at the proper amp rating. Just because someone tests, for example, cat5 cable to blow at a specific rating, doesn't mean the cat5 cable you have will blow at the same rating. It is your job to test and verify the claims.

The only sure fire way is just buying something like glass axial fuses, which even those should be tested as AverageJoe and a few others have found that they can have a little bit of variance on batches even with the same rating fuses.
 

floydR

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Aug 23, 2017
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If the wire is plated with silver (not nickel plated or tin plated) the wire will likely conduct more Amps as silver is one of the better conductors. So will conduct higher Amps before heating up in theory.
Later floyd
 

JonCombat

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Jan 11, 2022
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Thanks for the info, I will test a piece. how much current can a typical 18650 2500maH produce safely without damaging the battery?
 

Korishan

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Thanks for the info, I will test a piece. how much current can a typical 18650 2500maH produce safely without damaging the battery?
Depends on the cell chemistry. Some are designed to do 20C, others 0.5C. You need to look up the datasheet for your cells.

However, in general, it is advisable to have a fuse rating around 2-3A as you want to keep normal cell current around 1A. This is to increase the life cycle count of the cells.
But, you can design it for what ever type cells you have. If you have some that can do 20C, and you plan on running it at that high amps, then fuse accordingly.

Fuses at the cell level are to protect the pack from from the cell in case the cell goes short circuit. The sudden in rush of current will pop the fuse and help to keep the cell from going thermal runaway.
 

CrankyCoder

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Mar 11, 2017
Messages
95
Depends on the cell chemistry. Some are designed to do 20C, others 0.5C. You need to look up the datasheet for your cells.

However, in general, it is advisable to have a fuse rating around 2-3A as you want to keep normal cell current around 1A. This is to increase the life cycle count of the cells.
But, you can design it for what ever type cells you have. If you have some that can do 20C, and you plan on running it at that high amps, then fuse accordingly.

Fuses at the cell level are to protect the pack from from the cell in case the cell goes short circuit. The sudden in rush of current will pop the fuse and help to keep the cell from going thermal runaway.
This is what I was looking for :)
 
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