Actual Test of Pure Nickel Heat?

[rg12]

Do you guys know of any video/thread where they actually have done a test on heat of pure nickel strips indicating the thickness, width, how much current and for how long?

 

[kdog]

I vidoed a test I did on a 10mm x. 2mm strip, ramped it up from 10-80amps. Unfortunately I couldn't upload it to the tube, my old phone couldn't do it. But it was bright red/yellow by 80amps and melting. I remember touching it at about 30 amps and burning my finger. I think it was just starting to glow at ~50amps. It was a while ago so I can't remember clearly. Strip was pure nickel, in open air, about 100mm long.

 

[rg12]

I vidoed a test I did on a 10mm x. 2mm strip, ramped it up from 10-80amps. Unfortunately I couldn't upload it to the tube, my old phone couldn't do it. But it was bright red/yellow by 80amps and melting. I remember touching it at about 30 amps and burning my finger. I think it was just starting to glow at ~50amps. It was a while ago so I can't remember clearly. Strip was pure nickel, in open air, about 100mm long.

I need to know if a 3cm piece of pure nickel 6.75mm wide and 0.2mm thick can handle 7.8A without heating up...

 

[DjSpaceGhost]

A 7mm wide by .2mm thick strip of pure nickel can safely handle 9.5amps so I would say definitely so .

 

[rg12]

A 7mm wide by .2mm thick strip of pure nickel can safely handle 9.5amps so I would say definitely so .

Is it 9.5A constant with no heat?

 

[liveforphysics]

A 7mm wide by .2mm thick strip of pure nickel can safely handle 9.5amps so I would say definitely so .

Is it 9.5A constant with no heat?

It's making heat, if it's enough to be a problem is a more complex question.

Nickel will be making ~4.1x the heat of copper of the same dimensions. The real question with setting up nickel spot welds isn't about getting the weld to work, but not causing cell damage.

 

[rg12]

A 7mm wide by .2mm thick strip of pure nickel can safely handle 9.5amps so I would say definitely so .

Is it 9.5A constant with no heat?

It's making heat, if it's enough to be a problem is a more complex question.

Nickel will be making ~4.1x the heat of copper of the same dimensions. The real question with setting up nickel spot welds isn't about getting the weld to work, but not causing cell damage.

I will be using a 6.75mm wide 0.2mm thick nickel for constant current of about 6.5A
Will it not go hot enough while it's sitting on the cell holder plastic?

 

[DjSpaceGhost]

For some reason my response didn't post yesterday. It will not get hot enough to damage plastic cell holders at less than 7 amps.

 

[rg12]

For some reason my response didn't post yesterday. It will not get hot enough to damage plastic cell holders at less than 7 amps.

Thanks alot

 

[redilast]

Yes, I've done testing:

 

[redilast]

I will be using a 6.75mm wide 0.2mm thick nickel for constant current of about 6.5A
Will it not go hot enough while it's sitting on the cell holder plastic?

You will be just fine. Likely your nickel will be <10C above ambient temperatures at that current.

 

[rg12]

Thats super useful thanks alot
btw, for how long did you "stay" on each current for the test?

 

[redilast]

Thats super useful thanks alot
btw, for how long did you "stay" on each current for the test?

I did the test a couple years ago. It was either 5 or 10 minutes. Certainly long enough to heat soak the material.

Keep in mind that real world results will vary a little. This testing was done with the nickel in "open air" on both sides.

 

[flippy]

how long was the strip?

 

[kdog]

In my mind temp is proportional to R, cross section and amps only (for a given environment ). Length doesn't affect temp. L affects total power dissipated bc it is related to R. So I don't think length is important for peak temp consideration. Sure, it's important when looking at total heat loss which is basically power dissipated, but X amps through Y cross-section should reach the same temp no matter the length. Voltage required would change hence power, but temp would be same.
Am I right?
Or wrong?

 

[izeman]

I have a super stupidly constructed 10s4p bottle battery, where ALL series connections are done with 7-8mm wide 0.15mm nickel strips.
Even though the max current draw should be around 12-15A, this is a lot of stress on the little nickel connections. Otherwise i don't know if it's worth it to weld another layer of nickel over the first one ...

 

[protoham]

Attached should be the table I use.

 

[Matador]

Yes, I've done testing:

That is soo cool.
I'll add my table to this:
In my table that same 0.8 mm wide x 0.15 mm thick pure nickel strip is rated 4.9A, which is about 5 degree celcius above room temp judging from your graph...

Matador

 

[flippy]

That is soo cool.
I'll add my table to this:Ampacity (Powestream extrapolation).jpg
In my table that same 0.8 mm wide x 0.15 mm thick pure nickel strip is rated 4.9A, which is about 5 degree celcius above room temp judging from your graph...

what is your derating factor? temperature? if so what themperature is that? the ratings seem "conservative"....

 

[Matador]

That is soo cool.
I'll add my table to this:Ampacity (Powestream extrapolation).jpg
In my table that same 0.8 mm wide x 0.15 mm thick pure nickel strip is rated 4.9A, which is about 5 degree celcius above room temp judging from your graph...

what is your derating factor? temperature? if so what themperature is that.

I extrapolated values from powerstream.com (thus used their specified derating, temps)
"Maximum amps for chassis wiring"
https://www.powerstream.com/Wire_Size.htm

This is meant to give some ballpark estimate as it is extrapolated, but it's quite conservative...

On the other hand the resistive values are exact (Ohms/meter for different specified strips of different specified metal types)...
So it's possible to calculate heat produced from ohm's law: Power (watts) = R x I^2,
where R (in milliohms) = resistivity (in milliOhms/meters* lenght of strip used (in meters).

The resistivity values are in red in the table.
The extrapolate ampacity are in blue in the table.
I initially made this as a guide for myself, but wanted to share with other (could not find anything better on the web). I'm a scientist but not a electrician though... Did my best

Matador

 

[Matador]

Here are my original excel files
View attachment Metal Strips Ampacity & Resistances by Matador.xlsx

 

[flippy]

right, powerstreams charts are indeed VERY conservative.

the chart assumes a strip length of 10 meters instead of 10cm or so, that is probably why the values are so low.

 

[Matador]

So voltage drop, heat production all depend on resistance, gauge used, conductive metal type and lenght, for a given maximal tolerable voltage drop... is what I understand from all this....

How do we define what is an acceptable voltage drop for our EV application...
Is their a sort of consensus ? I was asking myself that but could not find an answer (well in real, I just didn't want the thing to cook and sag like hell when pulling amps).

Ex 0.02V drop max over a 10 cm conductor strip as an acceptable benchmark

 

[flippy]

voltage drop is not the metric one should focus on, temperature is key.

as long as the strip remains below 60ish degrees the standard aliexpress ABS cell holders and cell wrap wont lose strength or warp.
you can bump this a bit if you use that green paper rings as extra insulation.

personally i would not allow any part in my batteries get above 50c.

in the coming week i wiill be doing some temperature and high current tests with different sizes strip.

 

[Matador]

voltage drop is not the metric one should focus on, temperature is key.

as long as the strip remains below 60ish degrees the standard aliexpress ABS cell holders and cell wrap wont lose strength or warp.
you can bump this a bit if you use that green paper rings as extra insulation.

personally i would not allow any part in my batteries get above 50c.

in the coming week i wiill be doing some temperature and high current tests with different sizes strip.

Cool. Looking forward to see your result...
Heat is not good indeed.
And if it heats up.. it means their is resistance. Which means voltage drop.
I tend to aim for the highest possible voltage a system (batt-controller-motor) can yield. Less sags means the same system will have a slight increase in power (P = V x I, where V (voltage) is bettery kept as high as possible, by minimizing voltage sag due to heating nickel strip conductor resistances)