Best practice to extend battery stud

OM617YOTA

Solar Enthusiast
Joined
May 27, 2021
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119
I'm setting up an 8S pack of Eve cells with M8 welded studs, and the studs are too short. In the middle of the pack, where the bus bars and BMS leads connect, it's fine, though not ideal. At the ends, where the thicker cable lug connects at each end of the battery, it's flatly unacceptable. Especially so on the positive side, with the BMS and shunt power leads in place. The nut is grabbing maybe 2 threads on the stud.

Current plan is to put a coupling nut on the stud, thread another stud into the top of the coupling nut, and connect the battery cable lug, BMS power, and shunt power to that stud. Make sure everything is clean, use no-alox, and inspect frequently. This isn't ideal, but ideal isn't an option. Just meant to be a better solution than only two threads on the nut grabbing.

I'm not the first or only one to have this issue, how are others handling it?

Thanks all.

IMG_20211114_113604.jpg
 

time2roll

Photon Sorcerer
Joined
Mar 20, 2021
Messages
2,427
Am I missing something? Is the copper lug all the way down? Even if the two ring terminals are removed there does not look like enough thread to fill the nut with just the copper lug.
 
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OM617YOTA

Solar Enthusiast
Joined
May 27, 2021
Messages
119
Nope, you've got it right, that's exactly the situation.

Yes the copper lug is all the way down, and no there aren't enough threads to fill the nut, even with the ring terminals removed.
 

DJSmiley

Solar Addict
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Aug 13, 2020
Messages
471
But in that case I would recommend supporting the busbar. Now, depending on the wire gauge and flexibility, it might put stress on the terminals.

In this particular image I would rotate the busbar by 90 degrees and securing it to the wood
 

Zil

Just another ass on the web
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May 27, 2020
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1,334
There are quality lugs that are not as thick as that copper lug. Also that lug is not installed proper. Too small hole? Washer under lug?
 

BobR

Solar Enthusiast
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Jan 4, 2021
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138
A picture of the terminal/stud without the lug installed would help. Extending the stud and using it as a conductor is not a good idea.
 

OM617YOTA

Solar Enthusiast
Joined
May 27, 2021
Messages
119
Thank you all, really appreciate the help. So far I like the bus bar extension the best, but didn't get a chance to get back out to the shop to check what kind of room I have.

This connection in the photo I posted has lots of issues. It was never meant to be a final install, just temporary for capacity testing after top balancing.
 
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