What to recommend for fuse wire?

not2bme

not2bme

Member
Joined
Oct 16, 2017
Messages
517
Where are you folks getting your fuse wire from? I'm in the US so if anyone from here could chime in would be great!

I bought the 30AWG Remington buss wire form Amazon, but haven't got around to test what amperage it would hold. I think a battery cell shouldn't go past 3 amps? Would that be correct?
 
This topic has been discussed several times and several threads have been covered plus several videos which are also posted as well as links to recommended wire to use. Please use the search function in the upper right corner of the page.
 
35Awg tinned wire from UK via Ebay. 7 Amps or so. Said to be 5A.
 
Apologize to everyone that probably seen this thread a million times or already figured out where to get the wires. I have seen lots of info, some folks put up links, especially those in UK where actual fuse wire can still be found. But when I typed in 'fuse wire' in the search I often come up with lots of 'hints' but never the right link. Some folks use 35-40awg, but never disclosed where they got it or what brand it was or if they did any test on it. I was watching Pete's video on fuse wire where he switched from transformer wire to tinned copper wire and he had some link to a 20awg Remington Tinned Copper Wire on Amazon, and that didn't seem right compared to all the other people were using. I couldn't find any more fuse wire thinner than the 30awg Remington tinned copper wire on Amazon. So that's why I am trying to see what brands and gage other folks were getting.

So I hope this thread brings all the fuse wire to one thread.

Thanks daromer!!! :)
 
Understood. Maybe this is another item that could be on the FAQ ;)
 
mike said:
This is the fuse wire I use. Remington 30AWG tinned copper. Works great. I use it on both sides of the cell.
http://amzn.to/2xYOFsk
Click to expand...

Just ordered that. Thanks for the link Mike. A search on amazon pulled up wire that was insulated. I had a hard time finding it too.
 
But then you dont disconnect the cell if something goes wrong. Also heaters should have been picked out already from start. There is also some threads about this since before.
 
cmg_george said:
I have question regarding fusing the cells, i hope is the correct thread :)
Why is nobody using thermal fusing (like this one https://www.aliexpress.com/item/Fre...lgo_pvid=605d93ef-df40-4f7b-8fad-8e38b2de71d6 )

I was thinking that this should be much safer since the battery can get hot even if the current is not very high...
Click to expand...

The other reason for not using thermal fuses, or PTC fuses, is that they could cause a cyclic problem. They heat up, flip-off, cool down, flip-on, heat up, flip-off, etc, etc.

Update:
A thermal fuse is a cutoff which uses a one-time fusible link. Unlike a thermal switch which may automatically reset itself when the temperature drops, the thermal fuse is more like an electrical fuse: a single-use device that cannot be reset and must be replaced when it fails or is triggered. A thermal fuse is used when the overheating is a result of a rare occurrence, such as failure requiring repair (which would also replace the fuse) or replacement at the end of service life. [1]
One mechanism is a small meltable pellet that holds down a spring. When the pellet melts, the spring is released, separating the contacts and breaking the circuit.
Click to expand...

Ok, so those are different from PTC (poly fuses). So they won't reset. I see now why you asked the question. Hrmm...

Thermal fuses aren't easily seen if they've blown. So I see that as the greatest downside to them.
 
To be honest i'm not very sure on how they work. When i post the question i make the assumption they work as described by your Quote. For me looks like a very good safety feature but i did't saw anybody using them and i'm afraid that is something i miss.
 
daromer said:
35Awg tinned wire from UK via Ebay. 7 Amps or so. Said to be 5A.
Click to expand...


What is the advantage of using tinned instead of bare copper wire? With 15x the resistance of copper and a much lower melting temperature, wouldn't the tin fuse at lower current at a much lower temperature than the copper?

Or is it alloyed with the copper?
 
The tinn is on the surface and protect it from corrosion and makes it easier to solder.

Skickat frn min SM-G925F via Tapatalk
 
daromer said:
The tinn is on the surface and protect it from corrosion and makes it easier to solder.

Skickat frn min SM-G925F via Tapatalk
Click to expand...

That's what I thought. Corrosion shouldn't be a problem for a ttypical solar application. With a high enough current the copper will fuse. But what prevents the tin from melting aND separating from the copperat a lower current that won't fuse the copper?

Also, I really like mathematical models for design. Has anyone compared their fuse test results with Onderdonk's equation or other mathematical models for fusing currents?
 
Firstly, the wire should never got hot enough to melt the tin in the first place. If it is, you need to use bigger wire.
Secondly, the tin won't separate from the copper as it sticks pretty good to it. You would need to get hot enough to melt both the copper and tin to get it to separate like water/oil (well, water and alcohol).
Thirdly, umm, I'm sure there's something else to add here :p
 
And to get the tinn so go off due to heat then you have some special equipment because that is a very fine line untill it just burns of kind of.


Corrosion is a big problem with thinner copper since just some minor moisture and or weather will cause issues so there is frankly no use of pure copper wire as such. Unless you coat it but then you need to test the fusing with the coating too...
 
Korishan said:
Firstly, the wire should never got hot enough to melt the tin in the first place. If it is, you need to use bigger wire.
Secondly, the tin won't separate from the copper as it sticks pretty good to it. You would need to get hot enough to melt both the copper and tin to get it to separate like water/oil (well, water and alcohol).
Thirdly, umm, I'm sure there's something else to add here :p
Click to expand...
I'm not following. For the fuse to function, the metal must melt. Copper's melting point iso 1083C. Tin's melting point is 232. Tin has 15x the resistance of copper, so the tin would heat more rapidly than the copper. Sure, heat would transfer to the copper by conduction, but 1083C is far beyond the melting point of tin at 232C. When the copper is at 232C, the tin will be glowing. The copper is going to heat up at a rate proportonal to the current and act as a slow blow fuse at a current that has already melted the tin. Granted, there will be some adhesion, but...?

Of course, the heat will sinkto the other connected hardware. But will it balance enough to prevent the tin from glowing however long it takes the copper to fuse?

All of that heat from the 15x resistance is also conducting to connected hardware, including your cells. Will that heat be transferred away from your cells quickly enough?

daromer said:
And to get the tinn so go off due to heat then you have some special equipment because that is a very fine line untill it just burns of kind of.


Corrosion is a big problem with thinner copper since just some minor moisture and or weather will cause issues so there is frankly no use of pure copper wire as such. Unless you coat it but then you need to test the fusing with the coating too...
Click to expand...

The bare copper ground wire that is connected to my FLA lead weight is connected outside to a steel skirt around the foundation of my house, exposed to more moisture than the LFP battery will ever see, and it's not green yet. Granted, it's a lot thicker than #30, but...? Why would thinner wire be that much more susceptible to corrosion?

This pagesuggests that bare copper should be adequate and explains that corrosion resistance is excellent until temperatures are over 100C in high humidity and moisture. I'm still looking for more sources
 
Electricity will flow through the least resistance part of a wire. So, it will go from the source, through the solder connection, to the copper wire and then flow on the inside of the tinned copper. If you were able to take a voltage reading at the copper and at the tin on the outside, you'd probably see there is a difference in voltage, and definitely see a difference in resistance, as you mentioned tin having a higher resistance.
So, the copper will heat up first before the tin will. By the time the copper heats up to that point, it's about to pop anyways and the tin that's on there will probably melt/burn off and accelerate the heating of the copper to the popping point.
To be sure, as mentioned multiple times by various people, test what ever wire you plan on using as a fuse, regardless of what others have done and have shown.

I doubt the copper will last that much longer than the tin when it's about to fail. So no worries there.

The corrosion resistive power of bare copper wire to humid and wet atmospheres gradually decreases when temperatures exceed especially above 100 degrees Celsius when carrying currents. In such circumstances, Tin plating on the bare Copper wire protects Copper beneath it and improves longevity and strength of the fuse wire. Tin coating does not allow oxidation easily.
Click to expand...
Note, it says "especially" above 100C, not until 100C. Big difference. Also, it says doesn't allow oxidation "easily". It just severely hinders it.
 
Korishan said:
Electricity will flow through the least resistance part of a wire. So, it will go from the source, through the solder connection, to the copper wire and then flow on the inside of the tinned copper. If you were able to take a voltage reading at the copper and at the tin on the outside, you'd probably see there is a difference in voltage, and definitely see a difference in resistance, as you mentioned tin having a higher resistance.
So, the copper will heat up first before the tin will. By the time the copper heats up to that point, it's about to pop anyways and the tin that's on there will probably melt/burn off and accelerate the heating of the copper to the popping point.
To be sure, as mentioned multiple times by various people, test what ever wire you plan on using as a fuse, regardless of what others have done and have shown.

I doubt the copper will last that much longer than the tin when it's about to fail. So no worries there.

The corrosion resistive power of bare copper wire to humid and wet atmospheres gradually decreases when temperatures exceed especially above 100 degrees Celsius when carrying currents. In such circumstances, Tin plating on the bare Copper wire protects Copper beneath it and improves longevity and strength of the fuse wire. Tin coating does not allow oxidation easily.
Click to expand...
Note, it says "especially" above 100C, not until 100C. Big difference. Also, it says doesn't allow oxidation "easily". It just severely hinders it.
Click to expand...

That explains it a little better for me. i was trying to visualize the flow of current through each part, and just wasn't seeing it. Thanks.

I believe that bare copper should be sufficient , but as you noted it will require some testing.
 
You must log in or register to reply here.
Back
Top