The specification is not torque, it is force. It is 300 kg(force) = ~2938.5 Newtons.Jumping in here...
Is it 300kgf cm or 300kgf m?
If 300kgf cm, the the pressure should be 29,42Nm? That could be done with a torque wrench?
Or am I not reading it correct?
The specification from EVE is force. You keep saying torque. They are different. You want a constant compressive force.
A torque wrench is made to tighten a bolt to a certain force.The specification from EVE is force. You keep saying torque. They are different. You want a constant compressive force.
Well then you will need to take the diameter of your threads, the material of the fasteners, the pitch of your threads, the number of fasteners you are using, and any lubricant properties involved and do some heavy math to figure it all out to get to 300kgf. It will likely be in the several inch-pounds range. As for me, I just used the k values of my 4 springs and measured how much they were compressed to get to 300kgf.View attachment 101540A torque wrench is made to tighten a bolt to a certain force.
Basically when you use this tool, you tighten the bolt so the head of the bolt presses down into the material under with a specified force, measured in Nm.
Therfor i need the conversion....
A torque wrench is made to tighten a bolt to a certain force.
Force is not measured in Nm, Torque is. Force is measured in Newtons. Trying to calculate force applied to a fastener under a specified torque (*not* specified force) is very complicated. The reason is that the friction is completely unknown. A dry bolt will apply much less force than a lubricated bolt under the same torque. Force and torque are not the same thing.you tighten the bolt so the head of the bolt presses down into the material under with a specified force, measured in Nm.
more or less my approach. Clamped all 8 together with 4x m10 rods and plywood at the ends. Used a 17mm socket (without the handle) and hand tied it while the pack was more or less at ~90% SoC.In my world I have simply placed the cells, four deep, and made them tight without really any compression that I am aware of. I've done this at 85% ish state of charge. My goal is just to prevent them from expanding if they try to. Hopefully this will achieve most of the benefit.
Same here basically. However I did tighten my “plates” at about 80% SOC to about 8-in lbs. I have rubber mat inside between the aluminum plates and batteries w/ plastic mat separators between each cell.In my world I have simply placed the cells, four deep, and made them tight without really any compression that I am aware of. I've done this at 85% ish state of charge. My goal is just to prevent them from expanding if they try to. Hopefully this will achieve most of the benefit.
Force is not measured in Nm, Torque is. Force is measured in Newtons. Trying to calculate force applied to a fastener under a specified torque (*not* specified force) is very complicated. The reason is that the friction is completely unknown. A dry bolt will apply much less force than a lubricated bolt under the same torque. Force and torque are not the same thing.
The next problem you would face in the case of these cells is that your force is correct for exactly one charge value. They tend to expand a bit when they charge, and contract a bit when they discharge. This is due to the lithium ions moving and changing the density of the anodes and cathodes. The force specification is constant, to be applied under all charge conditions.
I'm going with 4x 75kg springs.Cool. Now tell us how YOU measure that.
Interesting. Your specification is apparently a swelling force test, not a compression specification for long-term cell use. What does the title sheet say?Initial compression force 300kgf has to be applied at ~40%SOC
Four 160# die springs on a single stack works well.Cool. Now tell us how YOU measure that.
This ? ..... seems like the new spec sheets confuse the issue instead of adding clarification.Interesting. Your specification is apparently a swelling force test, not a compression specification for long-term cell use. What does the title sheet say?