Threaded rod cell strapping and assembly

[idontknowwhatimdoing]

Hi All,

Have a 4s 280 xuba battery. My battery is going in a four wheel drive.

I'm going to go with plywood and threaded rod for now.
Does anyone put anything, like double sided tape or something grippy in between each cell to ENSURE no movement. Really want to protect the busbars/threads.

Thanks!

Building it today

 

[Tony]

Hi All,

Have a 4s 280 xuba battery. My battery is going in a four wheel drive.

I'm going to go with plywood and threaded rod for now.
Does anyone put anything, like double sided tape or something grippy in between each cell to ENSURE no movement. Really want to protect the busbars/threads.

Thanks!

Building it today

Here's my build using plywood and threaded rod. I didn't want problems later, so I using plastic over the threaded rods. Between the cells, I used 1/8" plastic spacers. I applied moderate tightness on the threaded rod and secured the pack to the frame, I think I will be fine. They are in a golf cart, and they seem very secure.

 

[idontknowwhatimdoing]

Thanks for the reply mate.
The 1/8” spacers you used, were they the full size of the cell?

 

[Tony]

Thanks for the reply mate.
The 1/8” spacers you used, were they the full size of the cell?

Someone recommended tile spacers and placing them at each corner and in the middle of the side of the cell. I used Troxell Horseshoe Shims 1/8" https://troxellusa.com/spacers-ts-shims-wedges/wedges-shims/1-8-horseshoe-shim-red-150-jar/
I made sure the U shape was up, so heat would not get trapped.

 

[Bob B]

I put a double thickness of double sided VHB tape on each corner of my cells and 1 in the middle also.

With 8 cells in a straight line, I could pick up the pack by the ends. I also put foam padding with hardboard outside that and pulled it tight with ratchet straps before tightening the bus bars.

 

[froehlichmj]

Here's my build using plywood and threaded rod. I didn't want problems later, so I using plastic over the threaded rods. Between the cells, I used 1/8" plastic spacers. I applied moderate tightness on the threaded rod and secured the pack to the frame, I think I will be fine. They are in a golf cart, and they seem very secure.

Tony,

Did you build your own golf cart battery system? I am a beginner and looking to do the same vs. lead-acid batteries.

Did you document your build anywhere?

 

[Tony]

Tony,

Did you build your own golf cart battery system? I am a beginner and looking to do the same vs. lead-acid batteries.

Did you document your build anywhere?

Yes, I did build the battery. I had six 8V Trojan batteries before. The built-in charger killed them, so I decided it was time to go LiFePo4. Measure, then measure again a couple of times to make sure the pack will fit in the space. You may also have to do some minor adjustments to the battery compartment of the cart.

 

[froehlichmj]

Yes, I did build the battery. I had six 8V Trojan batteries before. The built-in charger killed them, so I decided it was time to go LiFePo4. Measure, then measure again a couple of times to make sure the pack will fit in the space. You may also have to do some minor adjustments to the battery compartment of the cart.

Where did you get your batteries from?

 

[Tony]

They a re EVE 280AH cells. They are available through a number of sources, many of which are discussed on the forum. They are much more capacity than I needed. 200AH cell would have still been more than my Trojan batteries provided.

 

[fafrd]

They a re EVE 280AH cells. They are available through a number of sources, many of which are discussed on the forum. They are much more capacity than I needed. 200AH cell would have still been more than my Trojan batteries provided.

What source did you get your LF280s from and were you happy with the quality and then packing within-which they were shipped?

 

[froehlichmj]

RoyPow’s highest 48v comes with 160Ah, so 280Ah is incredible. How many miles do you think yours will get on a single charge?

 

[HRTKD]

If you're looking local for a lot of threaded rod, skip the hardware aisle at Home Depot and go to the Electrical aisle. Next to the Super Strut in that aisle there are 10' lengths of 1/4", 3/8" and 1/2" threaded rod for a cheaper price than the 4' sections in the hardware aisle. Check inventory before you go. My local store stocks the 3/8" and 1/2" but not the 1/4". Link to that threaded rod: https://www.homedepot.com/b/Threade...40,1519,1508,1507,1509&experienceName=default

I plan to get a 10' length and cut it to match my 4s battery length. I'll chase the threads after cutting it.

 

[apctjb]

Does anyone know what amount of torque should be applied to the rods????

Assuming 4 rods total, 2 on each side of the battery, what torque to apply to each rod to achieve EVE recommended containment pressure?

 

[BiduleOhm]

It depends on the thread type and metal type.

 

[Luthj]

There are clamping load tables for most fastener size/pitch and material combinations. Google is your friend.

 

[Luthj]

I just happen to be doing this calculation form my pack right now. This user friendly calculator might be helpful. I have not verified the math they are using, but it passes the sanity test.

Bolt Torque, Axial Clamp Force, Bolt Diameter Calculator

This fastener bolt torque calculator will Estimate the unknown torque, diameter, axial force applied and coefficient of turning friction for the given conditions.

www.engineersedge.com

 

[Zil]

Torque doesn't really enter in to this problem. There is a plate on each end of the battery pack. The rods are tightened to keep the cells compresed at the original size. I use Ny-lock nuts and tighten to firm against the cells.

 

[Luthj]

Torque doesn't really enter in to this problem.

Thats silly.

What SOC do you tighten the rods at? If the rods are over tightened, its not too hard to squish cells if you don't wrench much. If you just hand tighten the nuts at 100% SOC, there will be little or no force on the cells when the pack shrinks during discharge. The clamping force serves to keep the cells from moving around as well, which is a big deal in mobile applications.

I am not saying its critical to do so, but saying that nut tightness doesn't matter, when the manufacturer specifically lists a compression force value, seems a bit flippant.

I would note that self locking (such at nylock) nuts have additional drag torque, which should be measured and added to the final torque figure.

 

[HRTKD]

I just happen to be doing this calculation form my pack right now. This user friendly calculator might be helpful. I have not verified the math they are using, but it passes the sanity test.

Bolt Torque, Axial Clamp Force, Bolt Diameter Calculator

This fastener bolt torque calculator will Estimate the unknown torque, diameter, axial force applied and coefficient of turning friction for the given conditions.

www.engineersedge.com

What did you come up with for a torque value?

 

[Luthj]

What did you come up with for a torque value?

I have my plates clamping 2 rows, with 6 rods total. Thread is 1/4-20, zinc plated. The center two nuts need double the torque, as they are doing double duty. My back of the envelope math indicates 16.5 in-lb for the outers, and 33 in-lb for the inners. Though I need to review those figures to ensure accuracy. Since I am using nylock nuts, I will check the nuts drag and add that to the final torque figure. Its probably a few inch-lbs.