Comfortable with ~12 Amp fuse?

As safety is very important for me trying to run everything in the basement of my house im wondering if ~12 Amp fusing per cell is save enough?

Been looking a lot of videos from AveRage Joe he is using 2 Amp fuses. Is that better or what do you others think? Is the other option save enough?

Perhaps you could explain how you've decided 12A might be better than 2A ?

Its impossible to give accurate answers without knowing exactly what you intend to build.

Oh sorry, can we say classic 18650 packs? In the style of daromer or hbpowerwall with lets say 40p-80p 14S. The fuses are used on cell level. 12 Amps would be the current to blow fuses made of 0.2mm copper tined wire. I tried mine on a universal power supply.

I didn't decide whats better. I think 2 Amps would be better or more save cause i would not draw more than maybe 50 Amps out of the whole pack as i intend to use maximum a 5KW inverter. Maybe little more on 40S pack. But i wouldn't go on a 5Kw load anyway.

Just wanted to know if these 12A fuses could be too big and maybe burning cells or whatever could appear. Just in your opinion.

12A per cell fusing is excessive.

12A is a bit in the top. The fuse should be small enough that 1 cell can blow it but big enough to NOT blow when you hit your max limit.
Max current limit protection is the inline fuse before the gear you use. Using 1-2A fuses is for me in most cases way to small.

If your max current the cells ever will see is 1A your fuse should be ATLEAST 2A and preferable a bit more. I use 5A rated fuse wire and thats good enough.
Note that the blow current that for instance Joe test at to be for instance 2A at a 1A fuse wire is not the max rating you should use it for. 1A is concurrent rating and so should be.

Note that you dont have the cell fuses to protect towards what the pack can give out its to protect 1 single cell when it potentially shorts from being feed by the rest.. If you have a 80p pack we talk about 79 cells delivering current and that is easy 790A of current...

So my recommendation for packs with max 1-2A current per cell in worst case scenarios should be around 5A fuse wire. Not larger when using laptop packs.

If you plan doing a high current application that need to be on the edge of the cells capability then I suggest skip fusing them and only use the inline fuse.

Im not an engineer in this field but above is my understanding and built up knowledge from years of playing around with it...

Did you test your 5 amp fuse wire? Did it blow when a cell got faulty? I discovered that Joes are blown very often. Don't want that either.

Joes are to small if you ask me. It all boils down to what you want.

The 5A fuse wire blows when they should. Instant at about 170% of its rated capacity ie 8-12A depending on temperature and so forth. Buy proper fuse-wire or glass fuses and you wont have to worry about when they blow. The only time where you want to test when a fuse blows is unknown wire or unknown sellers. The instant blow you then need to consider half of that current as their rated current and then perhaps half of that as your rated max.

As said the fuse should ONLY blow when a cell gets a dead short. You should never be close to the cells limit so you want to use it as such a protection. Over current protection should be made on pack basis. Otherwise you will trigger a chain reaction of fuses blown.

I have not had a single cell go dead short on my as of now no. I have not had a single fuse blow either but many main fuses due to them protecting as they should!

Ok my wire glows and after short burns at 12 Amps. Done by room temperature. Will check again if i use it or not.

Maniac_Powerwall said:

Ok my wire glows and after short burns at 12 Amps. Done by room temperature. Will check again if i use it or not.

Click to expand...

When testing fuse wire you need to replicate the as installed conditions as accurately as possible, which includes length of wire and temperature when the over current condition occurs (or in your testing, when you apply it).

And I want to point out that for stuff that act as safety why guess or cheap out on them? For me fuse wire need to be legit fuse wire or fuses. I would not use anything else picked from a box in terms of wire

5A fuse wire is around 15USD and that roll of wire will last your life.... glass fuses arent that much more expensive either and you know their rating from the start.

Yes you're right but i didn't get a source for fuse wire in germany tried on ebay but couldn't find any. Need to check again saw that somewhere but don't know were it was. These glass fuses look so weak for me... I would be afraid to crack them!

The fuse wire that is 0.2mm is alot more fragile!! I bought mine from UK

The glass fuses aren't that fragile. If you put pressure on the glass section, then yeah, they'll break. But if you leave enough leg length to allow for the wire to flex, the chances of breaking the glass is slim. AveRageJoe does a lot of movement with his packs and rarely breaks a fuse.

Thanks for the link Daromer and i will see what i use.