Thicker is always better when resistance is concerned at such high currents we do(10A+).
However, there are design limitations in the case of a compression spring for a battery, mostly memory elasticity.
From the info I have gathered, 1,3mm is probably the limit, but a bit thinner for more room for elasticity is needed. So 1.2mm will probably be what I pick if there is a small cost difference, if any since I’m ordering more than a 1000pcs.
A spring is longer run of wire though so the drop is greater. However im not sure how to calculate that when the spring is compressed. Would it take a shorter path or would it have its own resistance? A 22 gauge wire and 19 gauge wire of double the length are almost the same
You do not want a spring this size in 1.2mm wire thickness, it is too thick, will be mechanically inferior and the coils will get in each others way. 1mm is plenty thick, already thicker than most steel springs the same size out there.
Since there are so many people wanting small springs too, I will now inform the manufacturer to make a batch of smaller spring with these dimensions along with the big springs:
- Spring top diameter: 4,5mm
- Spring bottom diameter: 5mm
- Spring thickness: 0,8mm
- Spring height: 8mm
- Plating: Zinc plating
Doing this allows for lower shipping costs and lower bulk costs per spring.
If anyone wants to change something about these dimensions above, say it to me.
The manufacturer has said that while it is possible to make 1.2mm wire without a cost increase, making a 1.1 mm is not directly available without a cost increase, so I will keep the thickness to 1mm as initially said, and corrected by djozz, as 1.2mm is too thick and will hurt memory elasticity and may make the spring collapse under a cell.
One other thing: would you prefer better spring mechanical properties using Beryllium Copper 38% IACS C17530, or slightly better conductivity using Beryllium Copper 45% IACS C17510?
I would like to know your choices.