Battery Pack Nickel Strip Calculator

[ludwig_bre]

Hi together,
Everybody here needs battery packs for foiling.
Many build these packs their own, wondering how thick the nickel strips need to be, how hot they will get, and if they even need nickel or if maybe steel is enough.
From my perspective, many people go way overboard on the thickness and most people could just use steel, from electric point of view at least (for rust, pure nickel may be better).

So was I, and that is why I made this caluclator.

Give the calculator inputs about your pack, like S&P Cells, Cell resistance, Strip width, … and get information about dissipated power and thermal increase of strips and cells.

From that, you can make an educated guess, which thickness is enough.

[ludwig_bre]

[Larsb]

That’s a great initiative! Many chase one percent improvement on the connection level while still driving the batteries hot and this type of calculator will show the relative level of thermal losses created.

It would be good to make this difference clear by showing the cell/strip heating relation as a number (in your pic it would be 24x higher thermal losses from batteries than from strips)

One thing: I doubt the strip heating temperature is correct since it is thermally connected to the batteries - if the calculator just uses the thermal mass of the strip and power loss to calculate that?

[ludwig_bre]

Thanks for the feedback
I will include percentage of Cell to Strip loss.

Yes, the calculator pretends, all energy lost in the strip is only going into the strip, in reality, most will be dissipated or go into the cells. So the calculator will tell you worst case, in a vacuum,…
But still you can see even with 0.15mm Nickel at 120A it only gets 25K hotter, so no need for 0.3mm Nickel or stuff like that.
Not really sure how to thermally model the thermal resistance from Nickel to cell, as this will probably depend on weld type, amount of spotwelds, …
If I had a average thermal resistance per Cell, from Nickel to cell, I could implement this as well.

[ludwig_bre]

I have included two new features:

1. Percentage of power lost in Strip and Cells (as requested by @Larsb)
2. Another thermal simulation for the strips, according to “ANSI / IPC-2221/IPC-2221A design standards for PCB trace width”
   Not sure how accurate this is, probably also depends on amount of thermally conductive/isolaive materials around the pack. But now there are two indications about thermals of the strips.