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value of the cell fuse
#1
dear forummembers.

what is the general value of cell level fuses to use?

for typical 14S60P or more, I see glassfuses of about 2 amp, 3 amp. 

This would be about 3 to 6 times the expected currentdraw, if I'm not too far off. (calculated at 500mA or 1000mA draw per cell)

if I have cells that have a capacity of 10Ah and a 1C continuous discharge rating and 3C max discharge, should I be looking for something like a 20Amp fuse?

if i put those cells in parallel (like 14S5P), i could normally safely draw about 50a from the pack. 

any suggestions?

Best regards

Stefaan
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#2
You should have the fuse below a cells max continues rating and above ur max draw. IF you plan 1a a 5a fuse Wire works great. Dont overcomplicate it.... Cell level fuses are NOT for overall current protection... That you got the Main fuse for. Main fuse should be max 1/3rd of ur cell level fuses IF you ask me
beserker786 likes this post
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#3
(03-12-2019, 07:00 PM)daromer Wrote: You should have the fuse below a cells max continues rating and above ur max draw. IF you plan 1a a 5a fuse Wire works great. Dont overcomplicate it.... Cell level fuses are NOT for overall current protection... That you got the Main fuse for. Main fuse should be max 1/3rd of ur cell level fuses IF you ask me

thanks for the reply:

for my setup: 1C = 10A, which would be the max continuous estimated current draw per cell.

so I may need a fuse of something like 20A per cell, maybe a bit higher. 

you suggest main fuse to be 1/3 of cell fuse. so maybe cell fuse at 30A- 40A and string at 15A?

I think this will be complcated to find glass fuses of this rating

best regards

Stefaan
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#4
Why 10A per cell? Do you use laptop cells? If you do that you should stay below 2A and preferable not above 1A...

Cells with 10Ah? What type of cells do you have then since it cannot be 18650 cells.
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#5
(03-12-2019, 07:13 PM)daromer Wrote: Why 10A per cell? Do you use laptop cells? If you do that you should stay below 2A and preferable not above 1A...

Cells with 10Ah?  What type of cells do you have then since it cannot be 18650 cells.

it's not a 18650, it a GP4105054T1000L, prismatic, but difficult to find spec. there is a post somewhere on the forum.

I'm still collecting 18650, slowly getting there.

my collection of 18650 is mainly from e-bike batterypacks. sometimes difficult to collect them, but mostly the bms is dead and the cells still test at +95% capacity.

I recently received 14 packs of 8 or 10 cells of the prismatic type (some are 10Ah, some 13.6Ah)

that's why I think I can go to about 10A-20A dischargerate for fuse

best regards

Stefaan

https://secondlifestorage.com/t-Testing-...=gp4105054
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#6
Ï would not even fuse those cells. But thats me... If you want to fuse them put the fuse at max 1/2 the cells max current so you have some head-room.
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#7
(03-12-2019, 07:24 PM)daromer Wrote: Ï would not even fuse those cells. But thats me...  If you want to fuse them put the fuse at max 1/2 the cells max current so you have some head-room.

not fuse?: living on the edge? :-)

I think I'm going to fuse, just to be on the save side, until I gain a bit more experience.

Ok, I will start googling for 15A fuses or something in that rating.

best regards

Stefaan
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#8
Those car fuses chould work ... but testing on cell voltage is advised.

https://www.benl.ebay.be/itm/Car-Fuses-S...Swgd1bdwKG
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#9
(03-12-2019, 07:48 PM)wim Wrote: Those car fuses chould work ... but testing on cell voltage is advised.

https://www.benl.ebay.be/itm/Car-Fuses-S...Swgd1bdwKG

more difficult to solder, but a good option if I can't find glass fuses

best regards

Stefaan
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#10
Living on safe side or not...The fusing was introduced on the smaller 18650 cylindrical LiIon cells. I would say those come from the same system basically and dont behave in same way and therefore I would skip it but thats me. If you are going to have 100s of them in parallel i would do different

Not hard to find datasheet for those cells? First hit on Google: http://www.farnell.com/datasheets/1708366.pdf
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