Use:
Nickel strips are used in the battery modules to connect the battery cells to the busbars. They will be spot-welded to both parts.
Pure nickel (not nickel plated steel which is also commonly available) must be used for its higher conductivity and thus lower power loss. Ideally, we would use the highest conductivity material available, however this is not possible due to the nature of spot welding. The resistivity of nickel allows enough heat to be generated during the welding pulse.
There will be styles of nickel strips in the battery modules. One will be a Long Nickel Strip which goes on the bottom of the battery module. The other is a Short Nickel Strip which will be on the top of the module.
Relevant Specifications:
Width - 7 or 8 mm (design works with both, 8mm is ideal due to lower resistance)
Thickness - 0.1 to 0.15mm (either will work, thinner will allow for quicker spot welding - depends on availability)
Material - 99%+ pure nickel (NOT nickel plated steel). There exist multiple checks for verifying this. One such test is a vinegar bath - if rust appears on the modules, they are nickel plated steel, if not, they are pure nickel. Another test is to take a grinding wheel to the strips, if the strips have steel, they will spark.
Amount Required:
Initial Information
| Strip Type | Number of Strips per Module | Number of Modules being Manufactured | Total Number of Strips Required |
|---|---|---|---|
| Short Nickel Strip | 12 | 30 | 30 x 12 = 360 |
| Long Nickel Strip | 6 | 30 | 30 x 6 = 180 |
Assumptions / Simplifications
The bent radii of the nickel strips can be ignored
OTHER ASSUMPTIONS?
Calculations
ADD CALCULATIONS
Add a safety factor of 1.5 or 2x
Results
HOW MUCH MATERIAL DO WE NEED?
Source For Material:
We will likely source the material from Aliexpress due to its abundance. Care must be taken to ensure that the supplier is selling pure nickel, and not nickel plated steel. Endless Sphere Forums is a good place to look for official links.
Alternate sources are 18650shrink.com (a US based DIY powerwall store), Sunstone Welders.
ADD LINK TO MATERIAL
Manufacturing:
The nickel strips will come on a roll. They need to be cut and formed into the shapes required.
Jigs for both should be created to increase manufacturing speed. It may just be one jig that serves both functions.