Pure nickel ampacity test

[Kevin525]

I did a simple test with a piece of pure nickel 30mm long and 6mm wide. I cut my positive battery output wire in half and soldered each end to this piece of nickel. I ran a constant current of 12 amps for 20 minutes and it never got hotter than 92 degrees F. The piece was wrapped in fish tape and 5 windings of kapton tape, too.

Everything I'm reading is stating this size nickel should only be able to carry about 7 amps or so continuously so I'm wondering why it's handling so much current without getting hot...

Any thoughts?

Thanks

 

[amberwolf]

Your battery output wire is carrying some of that heat away. The larger the gauge the more heat it will carry.

My guess is that is why it is staying cooler than you expected.

I don't know how the ratings for those are generated, but it could be that the limit is set to below the point at which temperature begins to increase beyond a certain rate.

Remember also that at least some of the heat generated by the strips will be passed into the cells (assuming the cells aren't already hotter than that). So minimizing the heat in them would be better.

 

[j bjork]

It would be interesting to know the voltage drop over the nickel during this experiment

 

[fechter]

Right, a lot of the heat is likely being absorbed by the batteries. You might try repeating the experiment with a longer strip of nickel.
While running the test, you can put a voltmeter across the strip and get the voltage drop measurement. Maximum ampacity for a conductor is usually rated with a large safety factor. 12ga. copper wire is rated for 20A, but I've run closer to 200A though pieces without overheating.