From the group buy and they came from Basen. Basen said it was tape residue.My terminals have similar small scratches & dents to yours but none of that adhesive / gunk. Where did you purchase your cells from?
From the group buy and they came from Basen. Basen said it was tape residue.My terminals have similar small scratches & dents to yours but none of that adhesive / gunk. Where did you purchase your cells from?
Basen as in ShenzenBasenTechnologyCo?From the group buy and they came from Basen. Basen said it was tape residue.
We used erasers for cleaning contacts!Some adhesives come off with a rubber eraser as well. Works great on solvent sensitive surfaces.
For sure, a hex on the flange, would help in so many ways. I would also make the flange a bit larger, to help with contact area.What alloy were your studs made of? Did you spec an alloy or did they just give you a 2xxx series? Personally, If I was having custom made studs made Id be asking for a 6xxxx or 7xxxx alloy. The vast majority of the cost is in labor so the extra material cost would almost be 0. One of those alloys would never have twisted of at 8nm. That said, its probably good it did sheer off though as if you had twisted much harder the terminal may have let loose from the cell, but you could have tightened them more than the 2nm and may not have come loose when you were taking the nuts off in the first place.
I really liked you solution, thought it was quite elegant (but a bit costly probably) after seeing yours and now hearing your issue, if I was going to do it, I think I might have the flange made with a hex so you could drop a socket over the whole thing and tighten it down with that instead of double nutting it.
Thanks for sharing your mishap, it is always nice to get a chance to learn, just sucks you had to deal with it......
A bit OT w.r.t. the subject of this thread, but I’m also seeking advice on how to most-effectively recover the one stripped terminal. My initial thought is to get one 1/4” stud and hope that I can self-tap it into the remains of the stripped M6 aluminum thread...
Had seen those but was shying away from them. The advantage is that you can have another M6 stud (like all the others) but the drawback is less aluminum terminal surface for electrical contact (and equal / matched electrical contact is a higher priority to me than matched studs).Check out the Helicoil threads here.
First of all, i am shocked that you stripped a thread at 4nm torque...i had no problems whatsoever at that setting. I stripped a thread, but it was through my own stupidity at a much higher torque.Had seen those but was shying away from them. The advantage is that you can have another M6 stud (like all the others) but the drawback is less aluminum terminal surface for electrical contact (and equal / matched electrical contact is a higher priority to me than matched studs).
So my thought is try the following in order of preference:
#1 1/4” self-tapping zinc-plated stud (or SS if zinc-plated doesn’t exist)
#2 JB-Weld an M6 stud into the stripped thread (do I need to enlarge the h
#3 tap in a larger thread (any advice on what size appreciated)
I know Helicoil will work but I’ll save that as my solution of last resort...
First of all, i am shocked that you stripped a thread at 4nm torque...i had no problems whatsoever at that setting. I stripped a thread, but it was through my own stupidity at a much higher torque.
I got a M7 spiral flute tap(still 1mm pitch) and retapped my thread to within a whisker of the terminal bottom. This suited me however, as i was ordering another M7/M10 aluminium flanged stud, so overall the resulting contact area would still be the same as the other cells above the flange. I'm not suggesting that M7 tap is ideal for your circumstance, only that for me, it tapped out fairly easily in the soft aluminium terminal.
On tapping for an M7 stud, I’m interested in any recommended products/tools and/or advice you have.Good luck with whichever way you decide to go.
ps...if tapping a new thread, the number one priority is that it is perfectly perpendicular to the cell terminal face....take your time and make this perfect...if tapping by hand tool......imho.
pps... filterguy suggested this in one of his resources(see link below)...might be worthwhile having a look at???
Silver-Bond 2 Silver Loaded Electrically and Thermally Conductive 2 Part Epoxy Adhesive
Silver-Bond 2 is a 2 part epoxy resin adhesive designed for electronic bonding and sealing applications that require a combination of good mechanical and electrical properties.epoxyinternational.com
Yeah, that’s what I figure (especially with my busbars with 7mm-wide slots).A few sq mm less contact won't matter much.
See link below for M7 tap. Just make sure you can get a M7 stud in the material you want, as this is an uncommon size. I was getting my flanged stud machined as a special in aluminium....just something to be aware of.The one that stripped noticeably differently than all 15 others.
It’s entirely possible that that terminal has a defective thread when it arrived - I made a cursory inspection but did not partially thread-in a bolt and check for play, for example.
All terminals were treated the same throughout, so it was nothing in my end that could have caused that thread to strip.
13 threads in a row tightened to 30inch-lbs and then reached 35inch-lbs with a last final (gentle) push of the torque wrench.
That 14th terminal reached 30inch-lbs like the others but then just stayed there and rotated when I gave it that last little push to reach 35 inch-lbs.
I left it as-is and debated easing up on the final 2 terminals but did not - they both reached 35inch-lbs like the first 13.
When I disassembled I inspected all terminal threads and sure enough, that 14th terminal was visibly stripped compared to the others.
I’ve been very gentle with all terminals before this calibrated tightening with a new torque wrench, so my best guess is that this (budget) 280Ah cell arrived with a defective thread (and possibly
Hadn’t known M7 was an option and it sounds preferable to M8. Where did you get your M7 spiral flute tap?
With the M6 holes, total surface area of the terminal is 227mm^2 - 28.3mm^2 = 198.7mm^2.
With an M7 hole that surface area is reduced to 227mm^2 - 38.5mm^2 = 188.5mm2, a difference of just over 5%.
Only a JB Weld solution without enlarging the hole is likely to come closer than that, so I’m definitely interested.
Also, the solid busbars I’m using currently have 7mm slots, so in practice there will be no difference between an M6 stud and an M7 stud...
On tapping for an M7 stud, I’m interested in any recommended products/tools and/or advice you have.
On epoxy, I’m not counting on the stud yo provide much in the way of conductance and am relying on it primarily for clamp strength on the busbar, so if JB Weld has worked well for others, I’ll probably go with that...
Well thanks for the heads-up; that’s a bit of a hairball...See link below for M7 tap. Just make sure you can get a M7 stud in the material you want, as this is an uncommon size. I was getting my flanged stud machined as a special in aluminium....just something to be aware of.
HSS Spiral Flute Tap M7 x 1 7mm | eBay