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Xuba Electronics: DEAL - 280AH LiFePo4 cells. Purchase & Review

Would appreciate others chiming in with their successful torque specs for the 280AH Eve cells with m6 holes in the terminal...

Thinking of using JB weld on the studs to reinforce the aluminum threads.

25 Inch/Lbs feels very loose on my terminals...
 
I've just recently sent for a torque wrench that does 5nm - 25nm and calibrated to within 4% of spec. Now i'm wondering if i need to set it at the minimum 5nm instead of the 8nm i assumed the xuba spec referred to.
Stripping three threads is a nightmare and goes to indicate the lack of robustness these cells have in general.
I have now recieved my 6mm - 10mm flanged studs and will fix them in place once i get my thread locker adhesive, and all because of the fear of stripping these delicate threads.

flanged stud.jpg

Like darkstar said above, it would be handy to know how many nm these are routinely torqued to?
 
I've just recently sent for a torque wrench that does 5nm - 25nm and calibrated to within 4% of spec. Now i'm wondering if i need to set it at the minimum 5nm instead of the 8nm i assumed the xuba spec referred to.
Stripping three threads is a nightmare and goes to indicate the lack of robustness these cells have in general.
I have now recieved my 6mm - 10mm flanged studs and will fix them in place once i get my thread locker adhesive, and all because of the fear of stripping these delicate threads.

View attachment 30353

Like darkstar said above, it would be handy to know how many nm these are routinely torqued to?

I can confirm 8NM is WAY too much. I stripped the first 3 I tried at that setting.

The EVE spec sheet says:
"Remark: The pole is a double aluminum pole structure. The internal screw with size M6 is used in the
poles. The anti-torsion of pole is 8Nm. The torsion should be less than 8Nm when used."

Employing my best engrish I interpreted that as the torque spec for the bolt holes, as there is nothing more specific anywhere in the spec sheet addressing the torque of the bolts in the holes.

I am trying J-B weld to hold the studs in the stripped holes. If that does not work will move on to helicoil inserts.

I am also trying J-B weld in the non stripped holes to reinforce the threads. The only concern I have is that there is some small amount of residue of J-B weld on the terminal surface once the bolt or stud is threaded into the hole. I am hoping I can clean that up with a razor knife or something once it is dry...
 
I just torqued a bunch of nuts on stainless studs at 24 In/Lbs with no issues. Hopefully that is tight enough to make a good electrical connection.
 
One of mine stripped out even though I used red loctite. I have no idea why that one stripped. I wasn't using a torque wrench but I am sure I wasn't applying any more torque than I did to the other nuts. So I have no idea what happened. All of my other studs are fine on my 8S pack. Anyways, I got some JB Weld, reinserted the stud and am going to let it cure for a couple days. My hope is the nut will go on tight enough to fully charge the pack. Hand tight plus a little should be enough since I am charging at a low C rate. Once the pack is fully charged I will try to tighten down the nut more.

I have a new cell on reserve and when I receive it I will fully charge it and then swap cells. I do not want to go through top balancing again. I think some have used helicoils and/or re-tapped the thread to 8mm. I have found 6mm depth helicoils. But the problem still is the depth of the hole only being 6mm.

Regarding torque, I ordered and received a click type torque wrench. It doesn't work. I tried it on larger bolts and it doesn't click. I am going to return it. So I ordered and received a beam type torque wrench and I think 8nm is too much going by the feel of the wrench when approaching 8nm. I only tried it on one nut and it started to turn when I reached 6 or 7nm so I stopped. 25 inch pounds is 2.82nm and that seems light to me too. But it might be enough force to allow for the required current flow.

I can't say if JB Weld would be a better alternative to red loctite. With red loctite a primer is required if applying to different metals. I didn't use it but should have. I am seriously thinking about using JB Weld on my cell replacement.
I am also trying J-B weld in the non stripped holes to reinforce the threads. The only concern I have is that there is some small amount of residue of J-B weld on the terminal surface once the bolt or stud is threaded into the hole. I am hoping I can clean that up with a razor knife or something once it is dry...
All of the terminals need to be lightly sanded before doing anything. And you should check for burrs on your busbars around the holes. That needs to be sanded off too. If you get any JB Weld on the terminal simply wipe it off. I used a paper towel. I sanded all of my terminals, vacuumed them as well as vacuumed all around the cell, then used acetone to clean off the terminal. I will repeat this for the stud I am attempting to repair.


Like darkstar said above, it would be handy to know how many nm these are routinely torqued to?
I think that is a good question. Perhaps to enhance on that I would like to know how much torque is required for a good connection assuming clean and flat terminals and busbars.
 
Some people tap the stripped hole for M8 screws. But you have to grind off the end of the tap so you can get threads to the bottom.
You might have to grind of the helicoil tap too.
 
I was thinking of putting together a group buy for a Snap-On 1/4" digital torque wrench. However, given the reluctance there is to buying a $65 benchtop power supply for top balancing, I don't see anyone shelling out $475 for a quality tool, even if it could save their batteries.

I've used click torque wrenches before. Sometimes the click is just too subtle. The digital torque wrench I use beeps and vibrates to let me know I've hit the torque threshold.
 
One of mine stripped out even though I used red loctite. I have no idea why that one stripped. I wasn't using a torque wrench but I am sure I wasn't applying any more torque than I did to the other nuts. So I have no idea what happened. All of my other studs are fine on my 8S pack. Anyways, I got some JB Weld, reinserted the stud and am going to let it cure for a couple days. My hope is the nut will go on tight enough to fully charge the pack. Hand tight plus a little should be enough since I am charging at a low C rate. Once the pack is fully charged I will try to tighten down the nut more.

I can't say if JB Weld would be a better alternative to red loctite. With red loctite a primer is required if applying to different metals. I didn't use it but should have. I am seriously thinking about using JB Weld on my cell replacement.

When I use an adhesive like JB Weld (rarely) or Red Loctite (slightly more often) I think of them as a one and done solution. There is no adjustment after the cure. In an automotive situation, when Red Loctite is used, it only comes off with the application of heat, lots of heat. Because of that, once you use Red Loctite on a cell terminal, it's there forever in that state. You never try to tighten something where Red Loctite is involved.

I will not use any form of thread locker on my cell terminals. First of all, because - as has been stated elsewhere on the forum - anything applied to the threads changes the torque. A grease applied to threads allows a bolt to turn easier, putting more stress on what the bolt is threaded into. It's much easier to destroy threads that way. Secondly, I may change my mind later on the battery configuration and need to remove the lug, ring terminal or bus bar. I won't apply Noalox on the threads either as that acts like a lubricant.
 
My torque wrench is 1/4" Harbor Freight $9.95 special.
It works but I use it more for tightening the restraining fixture.

When I tighten my busbars down I use a 1/4" ratchet holding it over the socket in my fist so I don't have much leverage against the handle.
It's easy to forget when I use the handle. I haven't stripped any of these yet.
 
When I use an adhesive like JB Weld (rarely) or Red Loctite (slightly more often) I think of them as a one and done solution. There is no adjustment after the cure. In an automotive situation, when Red Loctite is used, it only comes off with the application of heat, lots of heat. Because of that, once you use Red Loctite on a cell terminal, it's there forever in that state. You never try to tighten something where Red Loctite is involved.

I will not use any form of thread locker on my cell terminals. First of all, because - as has been stated elsewhere on the forum - anything applied to the threads changes the torque. A grease applied to threads allows a bolt to turn easier, putting more stress on what the bolt is threaded into. It's much easier to destroy threads that way. Secondly, I may change my mind later on the battery configuration and need to remove the lug, ring terminal or bus bar. I won't apply Noalox on the threads either as that acts like a lubricant.
I thought Permatex red threadlocker was just the same as red loctite? I thought the idea was to get a permanent bond between the terminal threads and the lower stud threads only? Everything else can be removed, but the stud stays put permanently?
I assumed the minimalist smidgen of noalox between between the cell terminal face and the flange face of my stud would prevent future oxidation between the faces. Is this thinking flawed?
Above my flange, the copper braided busbar is tinned, so i wasn't sure if noalox was really necessary between the aluminium flange surface and the busbar surface?
 
When I use an adhesive like JB Weld (rarely) or Red Loctite (slightly more often) I think of them as a one and done solution. There is no adjustment after the cure. In an automotive situation, when Red Loctite is used, it only comes off with the application of heat, lots of heat. Because of that, once you use Red Loctite on a cell terminal, it's there forever in that state. You never try to tighten something where Red Loctite is involved.
I applied the loctite to the grub screws. The whole point of using it was to help prevent stripping of the cell terminal. I understand once it's cured it's supposed to be in a forever state. That's why I used it. I would think the torque applied to a nut screwed onto a grub screw would be the same as using a bolt in the cell terminal's hole?

I will not use any form of thread locker on my cell terminals. First of all, because - as has been stated elsewhere on the forum - anything applied to the threads changes the torque. A grease applied to threads allows a bolt to turn easier, putting more stress on what the bolt is threaded into. It's much easier to destroy threads that way.
Loctite is not a grease if allowed to cure properly. In my case is I did not use the primer. So maybe that one grub screw didn't cure.

I may change my mind later on the battery configuration and need to remove the lug, ring terminal or bus bar. I won't apply Noalox on the threads either as that acts like a lubricant.
I am referring to grub screws. I was hoping they would never come out. Nuts, ring terminals or whatever is not what I am referring to. I am only referring to the grub screw. The question still remains. How much torque is sufficient applied to the busbar to make a good electrical connection. You said you think you used 25 inch pounds. Is that enough? And is that enough to keep the screws or nuts tight enough so they don't come loose?
 
I applied the loctite to the grub screws. The whole point of using it was to help prevent stripping of the cell terminal. I understand once it's cured it's supposed to be in a forever state. That's why I used it. I would think the torque applied to a nut screwed onto a grub screw would be the same as using a bolt in the cell terminal's hole?


Loctite is not a grease if allowed to cure properly. In my case is I did not use the primer. So maybe that one grub screw didn't cure.


I am referring to grub screws. I was hoping they would never come out. Nuts, ring terminals or whatever is not what I am referring to. I am only referring to the grub screw. The question still remains. How much torque is sufficient applied to the busbar to make a good electrical connection. You said you think you used 25 inch pounds. Is that enough? And is that enough to keep the screws or nuts tight enough so they don't come loose?
We need to find out if 4nm or 5nm or 6nm is enough torque to suffice. It needs someone with an already destroyed cell to find the genuine 'stripping' point.
 
I dont understand why the manufacturers dont make the terminals from copper anyways...better heat dissapation, better conductivity, stronger metal, and most folks will be using copper busbars(less galvanic corrosion).....so better all round. How much more costly would they become with copper terminals versus an infinitely superior product?
 
My guess is that 5 or 6 is good enough.
Yes I would agree. I think the 8Nm refers to when the terminal pole will twist. Therefore I assumed the "less than 8Nm" meant exactly that as far as the safe torque for a nut.

Also it has been mentioned earlier that people have punched through the bottom of the terminal so I back off my grub screws 1/4 turn. I am not sure why @Darkstar feels it is necessary to put them in more than finger tight, especially when there is JBWeld at the bottom of the hole. I think that would put unnecessary pressure on the bottom of the terminal for no apparent benefit.
 
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It needs someone with an already destroyed cell to find the genuine 'stripping' point.
It is clear to me that it has been demonstrated that 8Nm is the stripping point in 3 out of 32 holes. While that may be considered only anectdotal information, that is statistically significant enough to me, particularly since the manufacturer says to use less than 8 Nm of torque. The important issue is to have a clean and smooth surface and to prevent the formation of oxide so that the connection between the buss bars and the terminal top has as little resistance as possible. To prevent the nuts from loosening I use Nordlock washers. I spent more to get Nordlocks with larger outside diameter and I use flange nuts to give the largest surface area to hold down the buss bar to the terminal top.
 
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We need to find out if 4nm or 5nm or 6nm is enough torque to suffice. It needs someone with an already destroyed cell to find the genuine 'stripping' point.
We don't need to know the stripping point. We need to know how much torque it takes to make a good electrical connection between the busbar and the cell terminal and then we can work with that. @Bob B just posted in the other thread he thought he read somewhere 4nm.
 
It is clear to me that it has been demonstrated that 8Nm is the stripping point in 3 out of 32 holes. That is statistically significant enought to me, particularly since the manufacturer says to use less torque.
I thought the 8nm point was because of what had been seen in the eve datasheet, but how do we know that in actual fact 6nm is the stripping point....as far as i can tell, we dont know for sure.
 
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