one single fuse per pack !

one sigle fuse per pack

Ok?

daromer said:

Ok?

Click to expand...

yes it work . i have tested with a single pack !. not heat at all. now i will connect six of them. stay tuned

Hmm, what is that supposed to tell us? I don't see any fuses there. But yes, sure, it makes sense to fuse a pack. It isn't a substitute for cell fuses though.

You should always have a series fuse so but I have no idea what your thread about 1 fuse is about?

DarkRaven said:

Hmm, what is that supposed to tell us? I don't see any fuses there. But yes, sure, it makes sense to fuse a pack. It isn't a substitute for cell fuses though.

Click to expand...

you will see it my friend .

from the looks of the photos, he is spotwelding the individual cells with nickel strip, and no fuse on cell level.
preparing a large block of 14SxxP, and only fusing the pack. (intending to add another six of those 14S blocks)

The ups (APC 3000W) is using 48V configuration, I think.

I think we will have to wait for.... heater, runners, fire, explosion...

Interesting to follow

best regards

Stefaan

Could you please wait for July 14th for chargingyour batery pack ?
it's our national day

I think this could end badly for the community and isn't following best practice we are all striving for.

Even though its not individually fused per cell basis thats something everyone will decide on. For instance its kind of hard or even impossible to find packs premade with LiIon that do have cell fuses (Lets not include Tesla).
So with that said I dont think its bad as such its just another way to do it and its all about the risks.

I have several packs here not fused on cell level (Though not on the powerwall that is LiIon) and still nothing blown up.

Have I said that one of the things I work with on daily basis is Risk analysis?

It look like the pack are 14S-40p
-If one cell in a S failled,it will be very dificult to locate the faulty cell
-if one cell short, all the other one will discharge INTO the short cell. If each cell give only 1A, the faulty cell will "receive" 39A.... she will burn and damage close other cells. Nothing will hapen to the main fuse as it is not in the short line...
remember : I = i1 + i2 + i3 eg...

StefaanDeRidder said:

from the looks of the photos, he is spotwelding the individual cells with nickel strip, and no fuse on cell level.
preparing a large block of 14SxxP, and only fusing the pack. (intending to add another six of those 14S blocks)

The ups (APC 3000W) is using 48V configuration, I think.

I think we will have to wait for.... heater, runners, fire, explosion...

Interesting to follow

best regards

Stefaan

Click to expand...

you are very kind !.

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StefaanDeRidder said:

from the looks of the photos, he is spotwelding the individual cells with nickel strip, and no fuse on cell level.
preparing a large block of 14SxxP, and only fusing the pack. (intending to add another six of those 14S blocks)

The ups (APC 3000W) is using 48V configuration, I think.

I think we will have to wait for.... heater, runners, fire, explosion...

Interesting to follow

best regards

Stefaan

Click to expand...

you are very kind , thank you .

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hbpowerwall said:

I think this could end badly for the community and isn't following best practice we are all striving for.

Click to expand...

thank you for your answer . i will continue and we will see if you have right !.

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cristof said:

Could you please wait for July 14th for chargingyour batery pack ?
it's our national day

Click to expand...

thanks for you answer , you are very kind !

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daromer said:

Even though its not individually fused per cell basis thats something everyone will decide on. For instance its kind of hard or even impossible to find packs premade with LiIon that do have cell fuses (Lets not include Tesla).
So with that said I dont think its bad as such its just another way to do it and its all about the risks.

I have several packs here not fused on cell level (Though not on the powerwall that is LiIon) and still nothing blown up.

Have I said that one of the things I work with on daily basis is Risk analysis?

Click to expand...

thank you for your answer !. as i say before i have allready a mini powerwall without fuses at cell level nad works fine !. you are the only ... that your thouts its like mine ! . we will see the opinions from the others ... when i finished my job ! . to ather friends ( not you ) .... why ? , battery packs from electric cars ( like tesla , nissan leaf , bolt ) they dont have full for each cell ? .... why ? battery packs from ebikes ? ( from 0.5kw to 50 kw ) they dont have cell fuse ????? . daromer you are veryu kind person and OPENMIND ! . thanks men for your suport

Note that i would personally NEVER use cells without individual cell fusesin powerwall when cells are from 2nd hand laptop cells. Thats the important part. But in your case im not sure what you are going to do?

My LiFePo4 18650 cells arent fused in cell level. BUT they are totally different than the common laptop cells we see.

Also note that there is different batteries in different systems. Tesla have individual cells. nissan leaf (most of them) done even have Lithium except the last series.
other that have built have built the packs based on brand new cells that are matched. Powerwalls like ours are built with 2nd hand cells at random = Safety is the first consern.

Lets talk a little bit about risk analysis. Stating that "it worked so far" is NOT an risk analysis.

The answer from cristof partly included a part from a risk. That what if 1 cell goes bad. If 1 cells goes short the rest of the cells WILL DUMP all their current into that one. Thats what the individual cell fuses are there to protect from!

With that said if you find a risk like the short issue that can happen. How do you prevent.
One thing is to add cell fuses.
The other is to understand the risk? What will happen if this happens. What is the risk?

The risk in worst case is big fire. Cell fusing reduces the risk. But there is also 1 more thing that reduces the risk and thats the internal CID protection that have not been brought up. That one "should" remove most of the fire risk since if it gets high current dumped it will disconnect due to high pressure of heat.
No guarantee though


So= Stating that nothing happened up untill now is not a valid answer

Well said daromer.

paraskevas I wish you well, but we are playing with fire ... literally ... to discount the energy potential in these cells and possible net effect of a cumulative failure may be catastrophic.

This is why the little extra effort is taken by the majority here. I honestly feel that for most of us wearehere to learn from both the successes AND FAILURES of those that have walked (and are exploring)this path before us. It is good that youdisplay pride in what you have built, but I do feel concern when one seems to presume they know better, for that is not the correct path.

We care, please take any and all warnings given here seriously to heart.

It is true. I have never seen a laptop battery with more than 4 cells in parallel. Most manufactures suggest not - even with brand new cells. Personally I use a 6 cell battery bank.

One of the best things fuses can do for you is if you accidentally short a cell while assembling a pack (one user posted pictures somewhere around here having done exactly that) the fuses saved his cells and some severe burns. Probably more likely that the fuses will save you from user error than a rouge cell. The CID should do its job.

Fusing cells does not have an significant effect on build times. If anything that thin wire is so much easier to solder.

THANKS FOR YOUR ANSWERS !!!!. I WILL MAKE AN EXPERIMENT ! . ONLY 1 PACK FROM THE SIX , IT WILL BE BUILD AS I WANT AND DO MY TEST !. SO STAY TUNED !

You dont have to yell (capital letters)

Hrmm, now, several times he mentions "test". Is it possible the video he's going to do is to show you why you use fuses at the cell level. And all the aforementioned comments on why you should cell level fuse will come to be visible as to why? Hrmmm.... I'm starting to get really curious now

Geek said:

It is true. I have never seen a laptop battery with more than 4 cells in parallel. Most manufactures suggest not - even with brand new cells. Personally I use a 6 cell battery bank.

One of the best things fuses can do for you is if you accidentally short a cell while assembling a pack (one user posted pictures somewhere around here having done exactly that) the fuses saved his cells and some severe burns. Probably more likely that the fuses will save you from user error than a rouge cell. The CID should do its job.

Fusing cells does not have an significant effect on build times. If anything that thin wire is so much easier to solder.

Click to expand...

Are you referring to "the incident" of Pete's? What a great learning experience and a testament to why things are done this way ...

the incident

Cheers!

neurocis said:

Geek said:

It is true. I have never seen a laptop battery with more than 4 cells in parallel. Most manufactures suggest not - even with brand new cells. Personally I use a 6 cell battery bank.

One of the best things fuses can do for you is if you accidentally short a cell while assembling a pack (one user posted pictures somewhere around here having done exactly that) the fuses saved his cells and some severe burns. Probably more likely that the fuses will save you from user error than a rouge cell. The CID should do its job.

Fusing cells does not have an significant effect on build times. If anything that thin wire is so much easier to solder.

Click to expand...

Are you referring to "the incident" of Pete's? What a great learning experience and a testament to why things are done this way ...

the incident

Cheers!

Click to expand...

Indeed this is the incidentthat I was referring to. There was also another forum user who had photos, they shorted a cell while soldering it. They killed the cell, and scorched the neighboring cells, but the rest of the pack was fine.

Both incidents could easily have, at the very least, set fire to the pack without fuses. When even a single cell fire can potentially cause injury, why risk a whole pack fire?