From the group buy and they came from Basen. Basen said it was tape residue.
Avoiding Galvanic Corrosion
- Thread starter fafrd
- Start date
Basen as in ShenzenBasenTechnologyCo?
I was a Calibration Tech for years. Part of the job was to remove stickers from expensive instruments and apply another one to replace next year!
I learned that anything with an oily base would neutralize the adhesive and allow it to be removed without damage. Goo-Gone, Goof Off, WD-40, coconut oil, it all does the trick (Works great on cars too!) Isopropyl alcohol removes the oil without residue and will not attack plastics like acetone.
I learned that anything with an oily base would neutralize the adhesive and allow it to be removed without damage. Goo-Gone, Goof Off, WD-40, coconut oil, it all does the trick (Works great on cars too!) Isopropyl alcohol removes the oil without residue and will not attack plastics like acetone.
We used erasers for cleaning contacts!
Solarfun4jim
Solar seduced :-)
Further to my post 209, i discovered i had a problem with one of my flanged studs. It appeared to be slightly warmer than all the rest of the studs at 108A discharge. Upon investigation, i found that a had a miniscule gap between the flange underside surface and the terminal surface. I believe i caused this when i was slackening off the torque nuts. I think i have inadvertently slackened off the stud from the 2nm i had previously applied. Unfortunately, because i had set the stud in threadlocker, when i tried to break it free again(after more than a week of curing), the soft aluminium stud snapped inside the cell terminal(only took about 8nm to shear)...so i had to drill it out and will need to re tap the cell, plus buy a new 'one off' stud. :-(
The upshot of all this experimentation, is that if i was redoing in the future, i think i would opt for simple and cheap 22mm length (M6)aluminium greenhouse bolts, set them in a good fixing of thread locker and ensure the cell terminal face is clean. Cut the bolt head off and you have the perfect 16mm stud protruding. Now that i have found, just how strong the thread locker was, i dont have the same fear of being able to tighen the stud down into the cell. See example of bolts below...
Greenhouse Nuts and Bolts Aluminium 22mm Long Square bolt or Cropped Spare Parts | eBay
Just highlighting my problem as a reminder, if working with aluminium, less corrosion, better conductivity, but easily sheared, so treat gently.
The upshot of all this experimentation, is that if i was redoing in the future, i think i would opt for simple and cheap 22mm length (M6)aluminium greenhouse bolts, set them in a good fixing of thread locker and ensure the cell terminal face is clean. Cut the bolt head off and you have the perfect 16mm stud protruding. Now that i have found, just how strong the thread locker was, i dont have the same fear of being able to tighen the stud down into the cell. See example of bolts below...
Greenhouse Nuts and Bolts Aluminium 22mm Long Square bolt or Cropped Spare Parts | eBay
Just highlighting my problem as a reminder, if working with aluminium, less corrosion, better conductivity, but easily sheared, so treat gently.
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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......
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......
Solarfun4jim
Solar seduced :-)
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.
As regards alloy used, it wasn't specified, as i dont know enough about this aspect.
I got a torque wrench and in tightening my bolts to 4Nm / 35inch-lbs, I managed to strip 1 of 16 aluminum threads (bummer
So I want to get studs into those remaining threads as quickly as possible and am considering to get zinc-plated studs like these: https://www.belmetric.com/index.php...AkDLEALw_wcB&zenid=c3gjqt75i3j03cm013igt00u96
These are plated in ‘yellow zinc’ but that should fit the bill as far as working to reduce the liklihood of corrosion within the aluminum terminal threads, correct?
Any downside to using these?
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...
So I want to get studs into those remaining threads as quickly as possible and am considering to get zinc-plated studs like these: https://www.belmetric.com/index.php...AkDLEALw_wcB&zenid=c3gjqt75i3j03cm013igt00u96
These are plated in ‘yellow zinc’ but that should fit the bill as far as working to reduce the liklihood of corrosion within the aluminum terminal threads, correct?
Any downside to using these?
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).
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...
Solarfun4jim
Solar seduced :-)
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.
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
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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.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.
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...
Yeah, that’s what I figure (especially with my busbars with 7mm-wide slots).
What do you think about the idea of a 7mm stud as compared to Helicoil?
Solarfun4jim
Solar seduced :-)
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
I retapped all my EVE 280 cells to use a helicoil with a 8mm * 1.25 thread. I then use 8mm stainless studs.
The benefit is they hold much better, and the studs fit my M8 blockmons and 5/16 terminal lugs.
With a drill press it's a quick job to get them all drilled to the correct depth.
I don't believe these cels are built with threaded terminals. I also believe the quality of that machining step is not that great as many of the original 6mm threaded holes were very poorly done and pulled out well below 36 in/lb.
The benefit is they hold much better, and the studs fit my M8 blockmons and 5/16 terminal lugs.
With a drill press it's a quick job to get them all drilled to the correct depth.
I don't believe these cels are built with threaded terminals. I also believe the quality of that machining step is not that great as many of the original 6mm threaded holes were very poorly done and pulled out well below 36 in/lb.
Well thanks for the heads-up; that’s a bit of a hairball...
