# Building an 18650 battery with individual cell fuse wires

**URL:** https://foil.zone/t/building-an-18650-battery-with-individual-cell-fuse-wires/5611
**Category:** Electronics (ESC, remote, batteries)
**Created:** [September 11, 2019, 7:57am UTC](https://foil.zone/t/building-an-18650-battery-with-individual-cell-fuse-wires/5611 "2019-09-11T07:57:58Z")
**Posts on this page:** 1
**Showing post:** 157

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### Author: ![Flightjunkie](https://foil.zone/user_avatar/foil.zone/flightjunkie/32/8316_2.png) [@Flightjunkie](https://foil.zone/u/Flightjunkie)
#### Post date: [May 25, 2021, 3:21am UTC](https://foil.zone/t/building-an-18650-battery-with-individual-cell-fuse-wires/5611/157 "2021-05-25T03:21:15Z")

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Li-ion batteries must be balance charged. Either with a smart charger that monitors each cell voltage, or with a BMS that monitors each cell voltage and can interrupt the charge current.

A balance board with a 2A discharge current is not enough to prevent damage to your battery, and or a dangerous thermal runaway.

There are a lot of reasons why the voltage can spike on any given cell group during charge. The charging system used must be able to stop the charge if a cell group exceeds 4.2 volts.

I have had many times when my charger stopped charging because it detected high voltage on a cell. Any Li-ion balance charger will do this.

Charging your battery the way you describe is extremely dangerous and sooner or later the battery is going to explode or catch fire. And if you haven’t seen what happens when a 2 Kwh battery goes it’s scary. It’ll burn your whole city block down and or destroy your car.

Once the battery has been damaged with cell voltage above 4.2 it’s a ticking time bomb. It might thermally runaway while on charge, or it might later while being stored or used.

Commercial built batteries that charge with a simple charger are protected by a BMS that monitors the individual cell voltage and can interrupt the charge current if a problem is detected. I don’t trust BMSs. So I balance charge.

These batteries demand respect. Please be careful.

🤙

> [@Lockdown Build - Wales](https://foil.zone/t/lockdown-build-wales/7790/75):
>
> Some before and after pictures of my day today, needless to say I never managed to go foiling wearysob. I was toying with the idea of doing a second build but now I’ve got no choice man_facepalming

 ![Screenshot_20210524-172440_Chrome](https://foil.zone/uploads/default/original/3X/5/1/51737b49a058e17b65761cd031a03fec54a3660e.jpeg)

> [@Lockdown Build - Wales](https://foil.zone/t/lockdown-build-wales/7790/96):
>
> Hi. I’m so sorry for your loss. But, it could have been much worse. Could have easily burnt your house down. sobcrossed_fingers It sounds like it was the BMS to me. I have had several BMSs malfunction on me. Mine didn’t catch fire but, the PCB board looked melted and burnt a couple times. Twice on a Onewheel, one on a electric skateboard. Since then I have removed all my BMSs. I balance charge externally with a hobby charger, and monitor individual cell voltage during use. Besides burning…

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