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I WARNED YOU ALL! MB31/MB30 huge issue terminal snapping off

What torque setting is everyone using for the double screw terminals? My battery box instruction manual said 9Nm which snapped off the terminal last time. I was thinking 4-6Nm.

Any thoughts? Thanks

Did you put a wrench or something on the terminal to counter the torque so all you were measuring was the threads and not tearing off the tops?
 
Mine said 7Nm and that's exactly what I used on my digital torque wrench.

Always go by what the cell manufacturer's datasheet says.
The cell manufacturer is EVE, but the box manufacturer is YIXIANG. Using double stud busbars and the instruction manual said 8-9Nm when I snapped the terminal off. Seems a few others have done the same.
 
Did you put a wrench or something on the terminal to counter the torque so all you were measuring was the threads and not tearing off the tops?
No - I didn't apply anything to counter the torque last time. I'm still trying to think of a way of doing this with my replacement battery.
 
No - I didn't apply anything to counter the torque last time. I'm still trying to think of a way of doing this with my replacement battery.


I can think of a few ways, simplest would be a stamped wrench of the right size so it is thin enough...or take a regular or crescent and grind it down flat....I have seen some wrenches at HF that might work for the purpose...
 
The cell manufacturer is EVE, but the box manufacturer is YIXIANG. Using double stud busbars and the instruction manual said 8-9Nm when I snapped the terminal off. Seems a few others have done the same.
Have to go with cell manufacturers spec the enclosure manufacturer has no idea on the specifics of which cell is being installed by end user.
 
The cell manufacturer is EVE, but the box manufacturer is YIXIANG. Using double stud busbars and the instruction manual said 8-9Nm when I snapped the terminal off. Seems a few others have done the same.
Did you also use the yixinang double hole cells ? and did the first one snapped off or did you put a few on 9nm torque already? any chance you can post a picture of the snapped parts , i also have the yixiang cells for my 2nd battery and would like to see if the weld was burnt in the pole itself or on the surface only.

Thanx,
Bart
 
No - I didn't apply anything to counter the torque last time. I'm still trying to think of a way of doing this with my replacement battery.
it is a two bolt terminal correct? if so there should be zero torque on the terminal if you have inserted both screws prior to tightening... it seems to me that as one bolt is tightened the cell would twist a little until it hits the limits of movement presented by the second bolt... if the bolt holes are that sloppy then all bets are off of course. just more eve junk it seems.
 
it is a two bolt terminal correct? if so there should be zero torque on the terminal if you have inserted both screws prior to tightening... it seems to me that as one bolt is tightened the cell would twist a little until it hits the limits of movement presented by the second bolt... if the bolt holes are that sloppy then all bets are off of course. just more eve junk it seems.

How does tightening one bolt against the other work? Won't the bolt youre not tightening be unscrewing while you're trying to tighten the other one?
 
Did you also use the yixinang double hole cells ? and did the first one snapped off or did you put a few on 9nm torque already? any chance you can post a picture of the snapped parts , i also have the yixiang cells for my 2nd battery and would like to see if the weld was burnt in the pole itself or on the surface only.

Thanx,
Bart
1000123356.jpg

It was tightening the last cell that caused the issue. The others were all okay, but of course the busbar stopped some movement as its connected to another cell and stops the torsional force.

The last one with a cable was tightened to 9Nm and broke the terminal off. I'm planning on only doing them to 7Nm now.
 
View attachment 268079

It was tightening the last cell that caused the issue. The others were all okay, but of course the busbar stopped some movement as its connected to another cell and stops the torsional force.

The last one with a cable was tightened to 9Nm and broke the terminal off. I'm planning on only doing them to 7Nm now.

The weld seems to be well burnt in on the terminal itself, and was also burnt in on the double pole it just sheared the material itself.

I wouldn't apply more than 4/5 Nm which is pretty tight already and sufficient. also clean the contact areas with a scoth brite and degrease with cloth and alcohol. I tightented mine with a socket screwdriver by hand and know its around 4/5 Nm.

I also cut some excess shrink tube from the busbars as it was getting locked between the busbar and terminal.
 
View attachment 268079

It was tightening the last cell that caused the issue. The others were all okay, but of course the busbar stopped some movement as its connected to another cell and stops the torsional force.

The last one with a cable was tightened to 9Nm and broke the terminal off. I'm planning on only doing them to 7Nm now.
I spy non threaded insert terminals.

The mark of the beast of knock off poor cell terminal welds.

I’d treat them with kiddy gloves as others mention.
 
Unfortunately I can't find any official advice on torque setting for the double screw connectors.

I was just hoping to find a commonly used figure as YIXIANG keep telling my 8-9Nm

this is what came with my 304 cells from eve

"Max Torque Force on Poles 6 N·m Max torsion, non-loosen. "
 
View attachment 268079

It was tightening the last cell that caused the issue. The others were all okay, but of course the busbar stopped some movement as its connected to another cell and stops the torsional force.

The last one with a cable was tightened to 9Nm and broke the terminal off. I'm planning on only doing them to 7Nm now.

Man... if I had built the whole battery and this happened at the very end... :mad: 🤬😡
 
If I had built the whole battery and this happened, I would have taken the photos, complained, and then broken out the TIG. Set it pretty hot and hit one small spot at a time, cool with a damp sponge, and go again. Not practical for production but ok in a pinch. Back in business in 20 minutes. Go ahead and flame me, I have my welding jacket on... :p
 
If I had built the whole battery and this happened, I would have taken the photos, complained, and then broken out the TIG. Set it pretty hot and hit one small spot at a time, cool with a damp sponge, and go again. Not practical for production but ok in a pinch. Back in business in 20 minutes. Go ahead and flame me, I have my welding jacket on... :p
I really want to see someone try this.
 
It's been discussed. Maybe in this thread. TIG is going to really heat up the cell. Laser welding is probably the way to fix it.
Oh I know it has been discussed. I still wanna see it attempted. With a camera recording, of course!
 
It's been discussed. Maybe in this thread. TIG is going to really heat up the cell. Laser welding is probably the way to fix it.
That is why I said one little spot at a time. If you hit it with higher than usual current, it will take only a few seconds to fuse a single spot. Then cool it. Repeat until all the way around. Not going to heat up the whole cell that way. If you use low current, it will take too long to fuse and allow heat to escape into the cell. Even aluminum has thermal resistance. This technique worked great on a thin aluminum generator end casting the other day. With lower current I was getting nowhere.
 
That is why I said one little spot at a time. If you hit it with higher than usual current, it will take only a few seconds to fuse a single spot. Then cool it. Repeat until all the way around. Not going to heat up the whole cell that way. If you use low current, it will take too long to fuse and allow heat to escape into the cell. Even aluminum has thermal resistance. This technique worked great on a thin aluminum generator end casting the other day. With lower current I was getting nowhere.

Take pictures along the way and list settings if you try it.
 

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