What is the difference between using pure nickel strip and nickel plated steel when DIY lithium battery packs?

Nickel strip is a material often used in series and parallels lithium battery packs. The width and material of the nickel strip should be selected according to the current of the lithium battery pack. In terms of material, there are two commonly used nickel strips: pure nickel strips and nickel plated steel.

What is the difference between their performance and actual use? Let’s analyze it below.

1. Overcurrent capability:

The internal resistance of pure nickel strips is small, and the overcurrent capability is stronger than that of nickel plated steel.

In routine use, the calculation formula is: pure nickel strip calculates the overcurrent capability according to 10A/mm², such as pure nickel with a thickness of 0.15mm*7mm wide, its maximum continuous overcurrent recommendation is 10*0.15*7=10.5A;

For nickel-plated steel, its calculation formula is usually calculated according to 7A/mm², that is to say, the maximum continuous overcurrent of nickel-plated steel with a thickness of 0.15mm*7mm is 7*0.15*7=7.35A.

It can be seen that the current that a pure nickel strip can withstand is about 1.5 times that of nickel plated steel. לָכֵן, when the current is the same, pure nickel generates less heat.

כַּמוּבָן, the above formula is for reference only, the overcurrent capability of the nickel strip is also determined according to the discharge time and the structure design of the battery pack.

2. Product stability:

Pure nickel strip is better than nickel plated steel.

Pure nickel strip has strong corrosion resistance. In the salt spray test, the corrosion resistance of pure nickel strips is obviously better than that of nickel plated steel.

If the lithium battery pack is often used in an environment with high humidity, nickel plated steel will easily rust, but pure nickel strips will not. This is also one of the favored advantages of pure nickel strips.

3. Spot welding:

During the packing process, the connection between nickel strips and cells are all resistance spot welding methods, like cylindrical cells, 18650/26650/32700, so the greater the internal resistance of the nickel strip, the more the welding effect is better.

The internal resistance of pure nickel strips is small, while the internal resistance of nickel plated steel is large. לָכֵן, in terms of spot welding effect and firm stability, nickel plated steel is more reliable. כַּמוּבָן, a pure nickel strip can also make up for this small internal resistance defect from the structure, comparing the spot welding position to open the 工-shaped groove and so on.

4. Price:

Pure nickel strip is about 3 times more expensive than nickel plated steel. So if take the battery pack cost into consideration, some people will refer nickel plated steel to lower the price of the whole lithium battery pack.