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i have an old laptop from which i removed the battery in order to repair it. There were 6 cells in total and 2 of them were bad. One of them was leaking cellfluid when i tried charginging and reviving it. The other 4 cells seem fine. I fixed the battery cells and was trying to put the battery back together but there is no voltage coming to the connector of the battery. I saw that there is no voltage coming to the connector and saw this component. Is that a fuse? what kind of fuse is this ans how can i check it?

thanks for every help in advanceenter image description here

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abdussamed17
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    The generic metal thing across C4 looks like a potential short. What happened to the SMD components overall? At a glance they look like sloppy hand solder work. – Lundin Feb 11 '21 at 13:49
  • Thanks a lot. I didnt mean that short looking thing but it is glue residue from the manufacturing process. Nice detail catch anyway. – abdussamed17 Feb 11 '21 at 14:57
  • You've already got the answer here, but for future readers here are links to some other relevant questions: "[What is this Externally-Triggered Fuse?](https://electronics.stackexchange.com/q/162846/101852)", "[What could be this component and what is its work? Is it a fuse or may be a protection resistor?](https://electronics.stackexchange.com/q/189316/101852)". – SamGibson Feb 12 '21 at 01:12

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Yes it's a controlled fuse, more precisely it's called fusible link.

https://www.schott.com/en-us/products/lithium-ion-battery-protectors/product-variants

Dexerials

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The fuse can melt, when large current flows through it like a normal fuse, extra it can melt with remote control as it has a in-built heater for melting the fuse.

If the BMS detects overvoltage, then it triggers the remote fuse blowing to prevent an explosion of the battery pack.

Marko Buršič
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    First time I've seen such a fuse so +1 for opening my eyes on this. – Andy aka Feb 11 '21 at 14:04
  • Thanks for the quick help. When i probe the 3 legs for continuity there are no connections between them at all. Does that mean this fuse is blown? – abdussamed17 Feb 11 '21 at 14:59
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    @abdussamed17 If you look at the equivalent circuit diagram it would make sense., if both parts of fuses are melted. Usually this kind of BMS has a MCU that has OTP(One Time Programmable) memory that had stored one bit saying that the pack is damaged. So even replacing the fuse or making a short, won't restore the fully working condition of the pack. – Marko Buršič Feb 11 '21 at 15:26
  • solution for fixing? – abdussamed17 Feb 11 '21 at 15:37