Specific fusewire

Dexter Johnson

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Could you guys post the exact fuse wire you are using? Amazon linkies get extra bonus points! I have watched a few fuse wire test vids, but I'm curious what is an easy test method? Is using the fuse wire to just do a direct short across 1 18650 enough? Any and all suggestions welcome!
 

daromer

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Batteriapan

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crud said:
Batteriapan said:

Hi!

Which diameter did you use ?

Best

Not sure, but I suppose 0.15mm, i.e. 3A without energy loss.

If you have a too weak fuse wire anda single cell dies and draw 100% from the other cells, then you'll burn the fuse ofthe good cells too.

The smaller the pack the weaker the fuse wire I've used. For this small 8p that I only draw some 100mA of the whole pack I've used a fuse wire that burns at about 2A. For my 20p that I use as powerwall I calculated toallow for 5A per cell before burning, even though I never draw more than 500mA per cell.

Someone else might have a better insight on this subject.
 

Zagy

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I have 2m of very thick copper multi-stranded cable, and a single copper strand is 0.3mm in diameter - as far as I checked this is good for about 6-7 amps. When I have enough cells to start the building of my powerwall I will probably use that.
 

crud

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Thanks for the info. I tried several fuse wires . Thats why i am asking as i wondered which is a good concerning the Amperage.

The one i tried is labeled as a 5 Amp Fuse Wire, but it burns at exactly 7 Amps.

So i recon that this is still the value to go, right? Allowing a max. of 5-6 Amps draw from the cell. Or is there still an opinion to go with a fuse that should burn at 5 Amps?

Thanks for the Info on the small packs, too.
 

daromer

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I have max draw of 1A. im using 5a fuse wire that burns at 7+. If you go with to low current fuses you instead add up a voltage drop due to resistance and this is also a factor.

A single good cell can easily do 10A and will blow it and dont forget that you have x other cells tied to it that can push 100++ current backwards and that will blow it fast.
 

crud

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Thanks a lot!

That finally clears my view on the issue. So i am good with the selected fuse wires that do carry 5 amps and burn at around 7 amps.

Its helpful you mentioned the issue concerning voltage drop.

i think i roger that by now and can go on :) thx!
 

Korishan

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Voltage drop is one of the main reasons for going with 48v. At 48v, the drop i a lot less than if it was at 12v with same length of wire.

Thats why powerlines can be so thin, because they run at kilovolts.
 

Alec_J

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I am having a difficult time sourcing cells. I would love to consider 48v but at the rate I am going I'll be lucky to get enough for a 24v pack. The problem I am wrestling with is if I do go 24v then I am invested in a 24v inverter. So there would be additional cost if I ever did convert to 48v. I ran another Craigslist add today. I'm hopeful someone responds.
 

daromer

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But as long as u got 14 cells or more its the same stored energy going 48v as doing 24v. So number of cells is no argument if u ask me. :)
 

Alec_J

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daromer said:
But as long as u got 14 cells or more its the same stored energy going 48v as doing 24v. So number of cells is no argument if u ask me. :)


So a 14s6p would be better than a 7s12p? That's what I'm looking at right now.
 

daromer

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Higher voltage no matter what will give you thinner cables and in many cases less loss :)

Though with that small pack perhaps its better to just run a 12v system and no inverter at all. You can always rebuild the pack later on. Though it depends on what gear you get hold of too :)
 

neilmc

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Rather than start a new thread, I thought I'd pop this in here in case it helps anyone.

https://www.bigw.com.au/product/gardman-30-m-clip-twist/p/WCC100000000265024/

Just from the gardening section of an Australian department store. The one I got from the store is branded differently to this link, but it might work as an abundant source of fuse wire. The roll I got blows at 7-8amp, but not being actual fuse wire, twist tie wire you find where you are might blow at a different load.

The plastic covering strips easily (I just pull it off with my finger nails).

I accidentally did a real life test with this. I dropped a magnet on the bench near a 4S10P pack I was playing with. The magnet attached to the cells in the pack. The fuse on the positive and negative side of one cell instantly vaporized

Then I carefully removed the magnet from the pack... no real damage. There was a very small patch of melted plastic on the cell holder.
 
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