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Creating a 3SP4 cell pack (First time)
#1
I am going to create a 3S4P pack with some 18650 cells that I got from some lightly used laptop cells.

Using: 8x Samsung ICR18650-22E and 4x LG LGABC21865, I am also going to make sure to charge them fully before connecting them.

[Image: H6nrw.jpg]

After doing some research I found that I needed a BMS circuit to protect the cells, so I bought a 3S 40A bmsI am also going to add a 3S balance cable with a header to the cells in series, so I can recharge it with my ISDT Q6 Pro. The main power cord is going to go through the BMS to reach the ISDT.


My question is, will the single BMS be enough to make sure the 18650 cells safe and won't react dangerously? I have seen you can add individual BMS circuits like these, would that be overkill to do? I also read somewhere that people use fuses but wouldn't the single BMS circuit board be enough?


This cell pack is going to power small Arduino projects, and I'll add this controllable voltage regulator to it as well. Do you guys believe that the battery display, would accurately display the power left in the cell pack?
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#2
The 3s bms is all you need. Those other 1s round bms in your link are usually for cells use on flashlights. I use fuse wire on all my builds even on lifepo4. Its mainly to protect from a shorted cell, something the bms wont protect from. Fuse wire is easy to install, doesnt add too much work to your build I recommend especially on recycled cells. I use 28 gauge copper wire some use tin copper as fuse wire. 

Since you will be using a balance charger to charge, your battery will be well protected and get a full charge. Its the safest way to charge lithium.
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#3
(06-08-2019, 05:56 PM)jonyjoe505 Wrote: The 3s bms is all you need. Those other 1s round bms in your link are usually for cells use on flashlights. I use fuse wire on all my builds even on lifepo4. Its mainly to protect from a shorted cell, something the bms wont protect from. Fuse wire is easy to install, doesnt add too much work to your build I recommend especially on recycled cells. I use 28 gauge copper wire some use tin copper as fuse wire. 

Since you will be using a balance charger to charge, your battery will be well protected and get a full charge. Its the safest way to charge lithium.

Thank you very much for your answer. I have been looking into using resettable fuses like these ones, would you have any experience with that?
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#4
(06-08-2019, 07:23 PM)Artonn Wrote:
(06-08-2019, 05:56 PM)jonyjoe505 Wrote: The 3s bms is all you need. Those other 1s round bms in your link are usually for cells use on flashlights. I use fuse wire on all my builds even on lifepo4. Its mainly to protect from a shorted cell, something the bms wont protect from. Fuse wire is easy to install, doesnt add too much work to your build I recommend especially on recycled cells. I use 28 gauge copper wire some use tin copper as fuse wire. 

Since you will be using a balance charger to charge, your battery will be well protected and get a full charge. Its the safest way to charge lithium.

Thank you very much for your answer. I have been looking into using resettable fuses like these ones, would you have any experience with that?

I'm curious Artonn, where will you be installing those resettable fuses, I think they are the ceramic type? Isn't it easier to use the polymer type?

Cheers!

metalorn.
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