CATL 271ah, EVE 280ah or Lishen 272???

[timeforagorism]

If I was buying them I would be concerned about the surface area of the flange. It doesn't matter to me if they do it all the time or not....lol.

It's my own observation and might not be anything to be concerned about. Since having studs welded is an option the buyers can decide. Thanks.

I assume the concern is there won't be enough surface area when pulling large loads? If someone was going to run these at like 100 amp max would your concerns be less?

 

[AussieSim]

Welded stud

I posted this in another thread. I would hope that the laser welding results are as follows

 

[Michael B Caro]

Is that a Lishen cell? Can you post a higher resolution photo? None of the terminals surface area is usable and busbars may not be a good idea. I am not so sure there is enough surface area on the flange for large lugs either. Also stainless steel is not a very good conductor. Not an expert in this area so I am just throwing it out. But I think it would be better for one to get the cells without the welded studs and use grub screws and a thread locker. And use a torque of no more than 4.5nm when tightening the nuts on the busbars.

I believe the suppliers use laser welding. That's what bullion told me when I was going to purchase the 202ah Lishen's from them. The Lishen 202ah cells have a large square terminal on them so it's not as much of a concern since the supplier can laser weld a square pad with stud to the large square terminal.

Here is the string of responses to your concerns:

"once the hole is broken. they can do nothing with the cells. that's why I do more screw pin.
this is screw pin customized for prismatic cell. and welded with high power laser.
it's aluminum alloy M6 base and alloy steel screw pin. we have both M6 and M8 for choice.
the M6 base is same as the cell surface area. and M8 is a little bigger than the cell.
Lishen 202 have new version and old style. the old version is big square terminal. new version is round like catl."

And of course the Lishen 272 is the round style like catl.
So, it appears as though I was incorrect when I was guess that they were getting cells with no hole or stud and then welding the stud on. That was my guess after having seen factory options of welding a stud on where there was no hole, or actually welding bus bars to cells to connect them starting with cells that had no hole or stud.
Instead, from what I can glean from what he said, it is a screw that has a stud. They screw it into the cell and then laser weld it in place.

 

[Gazoo]

I am not sure what they mean by "once the hole is broken" unless they mean once a hole is drilled into the terminal. And once a hole is drilled into the terminal it can be tapped. But they say once the hole is broken they can do nothing more with the cell except laser weld a stud?

It's my understanding a screw pin is a pin with threads. Think of a screw with half of the threads missing for example. They are saying the base is the same size as the terminal. But as far as I can tell, referencing the photos you posted, the top of the base is not the same size as the cell terminal.

It's also confusing they say the M6 base is made out of aluminum, and the pin is made out of some kind of steel. I could understand this if they are using an aluminum base and a steel screw pin. If they are using a steel screw pin, then how are they welding the base to the screw pin? Maybe the whole assembly comes with the steel screw pin already mounted to the aluminum base.

Very confusing to me. However if they are indeed using an aluminum base then that is reassuring.

Instead, from what I can glean from what he said, it is a screw that has a stud. They screw it into the cell and then laser weld it in place.

No I don't think it's that simple.

They mention screw pin and also say "the M6 base is same as the cell surface area. and M8 is a little bigger than the cell."

They are using some kind of base and I can see it in all of the photos you posted.

 

[Michael B Caro]

"Maybe the whole assembly comes with the steel screw pin already mounted to the aluminum base."
This is what I was trying to describe. Something specially designed and made to screw down into the M6 poll that has a stud on the other end but they do not rely on just screwing it in but laser weld it too..... I think.

 

[Gazoo]

Yeah, I am not experienced at all in the area of laser welding. And I don't know if the reduced surface area for mounting busbars or lugs will matter regarding current carrying capacity, although it is reduced quite a bit on account of the type of base they are using. I do think people need to be aware of this. Personally I don't know which way I would go. I guess we have to trust the suppliers know what they are doing. I know how difficult it can be to communicate with them due to the back and forth translations. Everyone needs to make their own decisions deciding on studs or screws.

 

[Surferdudemi]

I am not sure what they mean by "once the hole is broken" unless they mean once a hole is drilled into the terminal. And once a hole is drilled into the terminal it can be tapped. But they say once the hole is broken they can do nothing more with the cell except laser weld a stud?

It's my understanding a screw pin is a pin with threads. Think of a screw with half of the threads missing for example. They are saying the base is the same size as the terminal. But as far as I can tell, referencing the photos you posted, the top of the base is not the same size as the cell terminal.

It's also confusing they say the M6 base is made out of aluminum, and the pin is made out of some kind of steel. I could understand this if they are using an aluminum base and a steel screw pin. If they are using a steel screw pin, then how are they welding the base to the screw pin? Maybe the whole assembly comes with the steel screw pin already mounted to the aluminum base.

Very confusing to me. However if they are indeed using an aluminum base then that is reassuring.


No I don't think it's that simple.

They mention screw pin and also say "the M6 base is same as the cell surface area. and M8 is a little bigger than the cell."

They are using some kind of base and I can see it in all of the photos you posted.

I think "hole is broken" means you've stripped the threads. Remember that you're translating from Chinese and there's not always a direct translation to English idioms.

"Screw pin" = stud, I think

For M8, perhaps the stud is M6 to screw into the terminal and M8 for the upper half?

 

[Gazoo]

I think "hole is broken" means you've stripped the threads. Remember that you're translating from Chinese and there's not always a direct translation to English idioms.

"Screw pin" = stud, I think

For M8, perhaps the stud is M6 to screw into the terminal and M8 for the upper half?

That makes sense. But with either an M6 or M8 stud it's clear they are using a base. I think flange would be a better word to describe it? I am going by the photos posted.

 

[fission]

This video shows an example of a round stud before being welded on:

I am curious if anyone else has input on or experience with these welded on studs. Amy at Luyuan said they are starting to offer this service and I am considering it for the EVE LF105 cells due to concern over the m4 threading. She said they haven't laser welded the 105's yet so I would be a guinea pig.

An internal resistance test through the welded connection compared to a normal IR test would be nice to see. I will try to make that happen when they get the new cells in. She is going to send pictures of their studs to me when available.

*Sorry if this is a hijack, I can post this as a separate thread.

 

[Michael B Caro]

This video shows what round studs look like before being welded on:

View attachment 32797

I am curious if anyone else has input on or experience with these welded on studs. Amy at Luyuan said they are starting to offer this service and I am considering it for the EVE LF105 cells due to concern over the m4 threading. She said they haven't laser welded the 105's yet so I would be a guinea pig.

An internal resistance test through the welded connection compared to a normal IR test would be nice to see. I will try to make that happen when they get the new cells in. She is going to send pictures of their studs to me when available.

The supplier that I have that deals in a LOT of cells with studs, says they have a specially designed "screw pin" for adding the studs to the cells.
My understanding is that this "screw pin" has a screw coming out of the opposite side from where the stud is. It is screwed down into the threaded hole of the M6 poll and then laser welded.

I will try to confirm that 100% tonight and also see I can get a picture of said "screw pin" to be sure.

 

[timeforagorism]

The plot thickens! Thanks for all the updates everyone.

 

[fission]

The supplier that I have that deals in a LOT of cells with studs, says they have a specially designed "screw pin" for adding the studs to the cells.
My understanding is that this "screw pin" has a screw coming out of the opposite side from where the stud is. It is screwed down into the threaded hole of the M6 poll and then laser welded.

I will try to confirm that 100% tonight and also see I can get a picture of said "screw pin" to be sure.

That would be great to see. The whole stud/base assembly being screwed in before welding would inspire more confidence in the connection.

 

[Michael B Caro]

That would be great to see. The whole stud/base assembly being screwed in before welding would inspire more confidence in the connection.

I think so too......but at this point that is my interpretation of what I was told and with the language barrier.......a picture to be sure is almost a must.

 

[Gazoo]

I think so too......but at this point that is my interpretation of what I was told and with the language barrier.......a picture to be sure is almost a must.

Could you also confirm if the whole assembly is aluminum? Thanks.

 

[fission]

I assume the concern is there won't be enough surface area when pulling large loads? If someone was going to run these at like 100 amp max would your concerns be less?

In the example stud I posted earlier (with the round smaller raised pedestal, assuming M6 stud) I calculated the mating surface area to be ~19 sq. mm which would be equivalent in area to ~4.5 AWG. I don't know if a direct comparison to that size wire would be applicable. Maybe someone with more knowledge can figure out a safe amp rating for that area.

Regardless, it seems the square base that AussieSim posted would certainly be preferable.

 

[Michael B Caro]

In the example stud I posted earlier (with the round smaller raised pedestal, assuming M6 stud) I calculated the mating surface area to be ~19 sq. mm which would be equivalent in area to ~4.5 AWG. I don't know if a direct comparison to that size wire would be applicable. Maybe someone with more knowledge can figure out a safe amp rating for that area.

Regardless, it seems the square base that AussieSim posted would certainly be preferable.

I would tend to agree with the square base but from what I am told they are almost all going to the round one. That could be wrong though. I guess we will see as the 2021 stock starts coming on the market

 

[Just John]

Yeah, I am not experienced at all in the area of laser welding. And I don't know if the reduced surface area for mounting busbars or lugs will matter regarding current carrying capacity, although it is reduced quite a bit on account of the type of base they are using. I do think people need to be aware of this. Personally I don't know which way I would go. I guess we have to trust the suppliers know what they are doing. I know how difficult it can be to communicate with them due to the back and forth translations. Everyone needs to make their own decisions deciding on studs or screws.

I'm not sure if I would trust them too much, might just be a case of "if that gets your money, we'll do it ".

 

[Michael B Caro]

I'm not sure if I would trust them too much, might just be a case of "if that gets your money, we'll do it ".

That is one of the advantages of buying in a way that gives you enough buying power, that losing you as a customer is not worth what they would make on any individual order. Not to say that it could not still happen, just less likely.

 

[Gazoo]

I'm not sure if I would trust them too much, might just be a case of "if that gets your money, we'll do it ".

Honestly I am leery trusting all of the suppliers and I could have been careful about my wording. But I believe the reputable suppliers want to keep their reputation and are not going to send out cells with defective welding.

I don't believe laser welding is the problem here. The problem for some may be the current carrying capacity of a welded stud with flange and pedestal vs a tapped terminal due to the reduced surface area of the welded stud.

I am very interested to see the actual part they are using. The part just lays on top of the terminal without any pressure when it is welded according to the video fission posted. Just laying there it would not be very good at carrying current. Agree so far? So then we can get into the current carrying capacity of the weld. There is no welding rod used. So how far into the terminal, and under the surface of the cells terminal, does the weld go? From the little I have read about laser welding the weld itself is very strong but thin.

Like I said I am no expert on this and here I go over thinking things. And I know laser welding is becoming more popular attaching "things" to the cells terminal. I just want to know what is the current capacity of the stud? We already know the "standard" single busbar shipped with cells, screwed or bolted down to the cells terminal can carry a lot of current. How much current can these laser welded studs carry?

For me laser welding is an interesting topic since I was in the laser hobby years ago. I used to buy DVD burners just so I could harvest the burner diode and make lasers out of them....lol. It was fun and did required eye protection. Always been fascinated by all types of lasers.

 

[AussieSim]

Honestly I am leery trusting all of the suppliers and I could have been careful about my wording. But I believe the reputable suppliers want to keep their reputation and are not going to send out cells with defective welding.

I don't believe laser welding is the problem here. The problem for some may be the current carrying capacity of a welded stud with flange and pedestal vs a tapped terminal due to the reduced surface area of the welded stud.

I am very interested to see the actual part they are using. The part just lays on top of the terminal without any pressure when it is welded according to the video fission posted. Just laying there it would not be very good at carrying current. Agree so far? So then we can get into the current carrying capacity of the weld. There is no welding rod used. So how far into the terminal, and under the surface of the cells terminal, does the weld go? From the little I have read about laser welding the weld itself is very strong but thin.

Like I said I am no expert on this and here I go over thinking things. And I know laser welding is becoming more popular attaching "things" to the cells terminal. I just want to know what is the current capacity of the stud? We already know the "standard" single busbar shipped with cells, screwed or bolted down to the cells terminal can carry a lot of current. How much current can these laser welded studs carry?

For me laser welding is an interesting topic since I was in the laser hobby years ago. I used to buy DVD burners just so I could harvest the burner diode and make lasers out of them....lol. It was fun and did required eye protection. Always been fascinated by all types of lasers.

I've messaged Amy from Luyuan and Emily from Basen. Neither have done Lishen 272Ah laser welded studs.

Both have photos of the Lishen 202Ah with rectangular batter terminals with laser welded studs.