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Laser welded studs of screw in?

ericfx1984

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Purchasing some 230 amp hour Eve cells I'm trying to decide between laser welded studs or screw in studs?

Which one would you pick and why?
 
Purchasing some 230 amp hour Eve cells I'm trying to decide between laser welded studs or screw in studs?

Which one would you pick and why?
If drawing around 150 amps or less I would go with laser welded studs. This was tested by someone with good results. Screw in is very easy to strip but there are ways to minimize the risk. If drawing more than 150 amps then I would probably go with screw in studs because the terminal surface area is greater and capable of handling 1C loads with minimal loss at the terminals.
 
Some people reported laser welded studs breaking off. Apparently that wasn't the design the cells were originally engineered for.
The alternative:

 
Are you talking about the new screw poles (M6) from DOCAN?
DOCAN EVE230A.jpeg
 
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so if that (see above) is screw in, then is this laser welded post?
 

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I have the old school screw in terminals. I've had no issues with stripped threads, but I was careful. I probably would go with the grub screws if I was doing it over. I prefer the larger terminal surface area of the screw in type over the laser welded posts.
 
all of these 280Ah cell terminal types SUCKS. they should use at least M8 in place of M6 (M10 would be even better), too easy to break them! The Al surface is also a bad idea. Better would be at least some sort of copper plating (copper strip welded to Al base or so).

The truth is you would in fact need some professional Al welding equipment to make a good conenction with these terminals. Al just doesn't connect well due to oxide layer. At least you need electrician's Al paste for Al lugs.
 
Most TERMINALS are limited to 8Nm of torque regardless of connection method, i.e., it doesn't matter whether you use M6, M8, welded terminals, grub screws, etc.

it's not a thread limitation, it's a limitation on how the terminals are connected in the cells.
 
That 8Nm is based on strength of plastic housing holding terminal.
If you have a stud, most of the torque is expended in friction between nut and stud, and between nut and busbar.
If you can restrain those while tightening nut, the terminal/housing interface doesn't experience it.

With terminals like picture from cass3825 shows, it could be restrained by wrench.

If terminal was just an aluminum tab standing up with hole through it (like some battery types), tighten nut on bolt with two wrenches, and terminal/housing interface won't experience any of it. Plus you could use busbar or cable on both sides, 2x the area each getting same pressure.
 
I have 2 strings with grub screws and 2 strings with welded studs. I can see no difference in performance between the two.

You got to be real careful with grub screws. If the grub screw is not all the way down, for example only threaded in a couple threads, you can strip out the threads easy. Even with less than recommended torque.

I would buy all welded studs at this point.
 
Most TERMINALS are limited to 8Nm of torque regardless of connection method, i.e., it doesn't matter whether you use M6, M8, welded terminals, grub screws, etc.

it's not a thread limitation, it's a limitation on how the terminals are connected in the cells.
wrong. Terminals could have a nut to hold it with a wrench while tightening up, so you do not tighten it against the cell body but just against the terminal itself. It's just a bad design. Garbage design always comes from lack of lateral thinking. They could learn e.g. from a plumber

 
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