What fuses to use ?

Charlycop

Charlycop

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Jan 4, 2019
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Hi Guys,

I'm preparing my 14s20p battery for my workshop, in order to power 5m LED strip and maybe one inverter to power my tools sometimes.

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About the bus bars, I cannot find the fuses on AliExpress to link each cell to the bus bars. Where can I buy those ?

Thanks.
 
That depends on what you are going to put in and take out.
I will charge with ~500-600 mah per cell and discharge with ~200mah per cell.
But my wall is growing, so it will getting less and less per cell.
If you know what current draw there would be(charge or discharge) i would take 3 or four times the amount.

If you are going to charge with 1.5 amp a cell, then i don't think you want 1 amp fuses :)
A fuse is only for short circuit protection, so if your cell can handle 5 amp, you can do with 3 or 4 amp fuses.

But this is what i think.
What i also think:, i don't like "fuse wire", in case of a self discharger, the fuse wire will go very slow.
There is a point that it will form a glowing metal ball, i am not very fond of the idea that there is a possibility of a molting ball of metal in a place where i don't want him :)

To solder those fuses to your busbar there is a trick or two.
I like to twain two fuses together, and snip off half of the other end, bend them and then solder them, cell first.
Bend/fold the other end into the busbar, it will save you some burning marks or fiddling around with a extra tool(thus a extra step in the process)
Will make some picture's if wanted.

My two cents, hope this was helpful, best
 
its mA not mAh when we talk about current.

Secondly 1A fuswire should NOT be used. I would not even consider 1A on glassfuses. They are to small
The fuse on the cell level is for short protection on pack level and should preferable be 4-5x the size of the main fuse.

Do you want to change 100 fuses on the pack or 1 main fuse? So if you have 100p packs and your max current is 1A per cell. (We talk about the max burst the inverter ever can do) you should have 5a fuses per cell and 100-120A main fuse on the pack.

The main fuse can be found if you look at your inverter and then design based on that.

Lastly the cell level fuse is NOT protection against 1 cell but all others. Ie if you have 100 cells in a pack and 1 goes rouge the other can easily deliver 900A into that cell... I bet a 5A fuse is more than enough to protect ;)
 
@ daromer.
You think that 1a fuse for me is to light?
When i would use 14s100p one time, its 500-600 ma per cell charge and discharge at 200ma per cell
Before i take MY wall in to use, there will be 3 or maybe even 4 times a 14s100p.
That would calculate (please correct me if i'm wrong) at max 200 ma charge and 75ma discharge per cell.
But as i will continue with expanding, the currents that go in and out of the cell will get smaller?.

Thanks in advance.
 
The smaller the fuse wire, the more resistance will be incurred. Sure you may only pull 200mA, but a 1A fuse will have more resistance on it than a 2A fuse, even at 200mA. The fuse may degrade over time and fail just from normal use
 
Whoops :(
Ordered the wrong ones, 1A :(
I intended to do a annual check, if a pack with some bad 1A fuses i must desolder all of them.
And replace them with 2 or 3A glass fuse.

Keeps me busy and of the street....
 
Its not about how big it Will be in end but worst case. What is your Main fuse for 1 pack only? Since i Guess you want to be able to run 1 string the cell level fuses are made from this value.

Then after expandinh you can fuse each string with its own Main fuse IF needed.

Thats how i design Them.

I would say 1a is to low. IF you say max you see now is 600mA om pretty sure the battery pack see 2* that during surge :)
 
One string is one 14s? right?
So every string will have a main fuse of 60-80amp.

One "fuse box" can hold 4 strings that goes to the main line.
For a overall fuse i bought that one from batrium the: tripping unit with double pole circuit breaker fuse at 125A 15kA


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I could not find my 80amp fuses, and i must have a other brass unit.
So it will be good for 16 strings.

But if 1a fuses are to weak, order 2 or 3 amp? and what to do with 3000 pcs 1 amp fuses?

The first 5 packs have 2 amp fuses, desolder them?

Thanks in advance
 
Having Main fuse of 80a and then cell fuses att 1a IF you have 80 cells you Will see problem and burn your cell fuses. Get 4-5a fuses instead.

Bin the Ones you have or sell Them. You can Always use Them for other projecta but i would not have cell level fuses Close to the rating of the Main fuse on a string level
 
I just begin :

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Is it needed to use fuses at each end (+ and -) of each cells ??
 
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