Welded stud broke. How deep can I drill EVE LF304 terminals?

[peacefulcurrant]

One of the welded studs on my EVE LF304 broke.

My plan is to drill the terminal and tap the hole to use a grub screw instead. My question is though: How deep can I drill into the contact from the contact surface without damaging the cell?

Does anybody have an EVE LF304 cell with drilled contacts that they could measure for me? Or has anybody already done this and remembers how deeply they drilled without issues?

 

[zcskywire2]

Does anybody have an EVE LF304 cell with drilled contacts that they could measure for me? Or has anybody already done this and remembers how deeply they drilled without issues?

I will check at my office on Monday. We used to drill and tap LF280s and LF280Ns. We may have attempted to do LF280Ks and LF304s before switching to other attachment methods.

Absolute maximum depth on the LF280 and LF280N cells was 6mm deep from the top of the terminal. We drilled and tapped m4 bolts but I've seen it done with m6 bolts.

 

[VanDersie]

I don't have the product spec sheet of EVE-304, if you have this doc, please check the part of "Drawing"
In my experience, many assembly plants in China are used to drill with 6~6.5mm depth and M6 on the terminal of EVE-LFP cells.

 

[peacefulcurrant]

I will check at my office on Monday. We used to drill and tap LF280s and LF280Ns. We may have attempted to do LF280Ks and LF304s before switching to other attachment methods.

Absolute maximum depth on the LF280 and LF280N cells was 6mm deep from the top of the terminal. We drilled and tapped m4 bolts but I've seen it done with m6 bolts.

That would be great! Especially if you had data from a drilled LF304 cell. I am quite worried, that EVE has changed the internal geometry of the terminal from the LF280 to the LF304 to optimize the capacity.

 

[peacefulcurrant]

I don't have the product spec sheet of EVE-304, if you have this doc, please check the part of "Drawing"
In my experience, many assembly plants in China are used to drill with 6~6.5mm depth and M6 on the terminal of EVE-LFP cells.

I have the datasheet but I cannot identify a safe drilling depth from it. I will attach it. Maybe you can find something I missed?

 

[zcskywire2]

I have the datasheet but I cannot identify a safe drilling depth from it. I will attach it. Maybe you can find something I missed?

Well the first problem is at a minimum that datasheet has a mistake in it. Furthermore I think it's one that has been faked. The terminal spacing is 123mm center to center on lf304s, the cell drawing in that still has the old 90mm spacing of the LF280n and LF280. The full color diagram shows the old lf280 tops as well. Release date is very early as well. I image that one of the resellers couldn't get a real data sheet and photoshopped a 280n datasheet into a LF304 datasheet. I've seen it done before with the Lishen LTO cells.

All that being said, none of the EVE datasheets I've seen have the terminal thickness in them. The only ones I've seen like that are the newer CALB ones. The cells are mainly designed for laser welding so drill depth is left out of the sheets.

Edit: here is a link to another post in this forum with proper LF105, LF230, LF280K and LF304 cell specification sheets. https://diysolarforum.com/threads/the-newest-specification-sheets-of-eve-cells.45234/

 

[Steve_S]

I Word of Advice.
Remember that without the base from the welded stud, you now have an offset in height. This is not an issue with flexible busbars but it "is" with rigid bars, you will have make a "step" so that the bar is fully flush with the pad. If it it's possible, that terminal may be better suited for attaching (-) (+) out if using screws. Eve cells used to be tapped to 6mm depth with 6mm screw-thread before they went to the new format.

Hope it helps, Good Luck

 

[zcskywire2]

Before we get to much farther forward here, it would be good to know how the stud broke. Did the threaded part of the stud snap like some other people's recently or did the whole welded stud assembly break free of the battery terminal. It makes a difference in how you would attempt to recover the cell.

 

[VanDersie]

I have the datasheet but I cannot identify a safe drilling depth from it. I will attach it. Maybe you can find something I missed?

I have an older version of the LF280 spec sheet, maybe it can give you a point of inspiration.

 

[pelicanpebble]

@peacefulcurrant Can I ask where you got your cells? I ask because I have the same problem.

I got my cells from Amy at Docan Power. I followed their torque specifications to the letter and the bolts on their cells still broke!

 

[peacefulcurrant]

Well the first problem is at a minimum that datasheet has a mistake in it. Furthermore I think it's one that has been faked.

Thanks for the heads up. This datasheet came from Amy at Docan Power. That is really not inspiring confidence! Especially given the recent reports of them re-lasering the QR codes.

 

[peacefulcurrant]

Before we get to much farther forward here, it would be good to know how the stud broke. Did the threaded part of the stud snap like some other people's recently

Yes, the the threaded part snapped about 5 mm up from the base. Not really enough left to screw on a couping nut. - Any ideas?

 

[peacefulcurrant]

@peacefulcurrant Can I ask where you got your cells? I ask because I have the same problem.

I got my cells from Amy at Docan Power. I followed their torque specifications to the letter and the bolts on their cells still broke!

I also got my cells from Docan Power. My studs also snapped well below 6 Nm. I believe you are right: They are having quality issues with their studs.

 

[zcskywire2]

Yes, the the threaded part snapped about 5 mm up from the base. Not really enough left to screw on a couping nut. - Any ideas?

I will point you then in the direction of this thread to start. The poster had the same problem as you. On page two there are pictures where he took the cell to a machine shop and had them extract the broken stud and put threading in what remained of the laser welded stud.

Broken welded stud

So, I used too much torque on one of my welded studs on my Eve batteries. It broke off near the bottom. I've attached a picture. How do I fix this? Do I drill out the stud and tap a new larger thread in the terminal? I don't have much experience tapping threads. Would I be better off just buying...

diysolarforum.com

 

[zcskywire2]

Since I did say I'd report back on our prior drilling and tapping. We have no drilled/tapped LF280K or LF304 cells. I did find some of our old LF280s, tap depth was 5.7mm. picture included. Placement of calipers obv do not indicate measurement direction, only for visual reference. Yes they are terrible calipers, but they are plastic for no shorting.

 

[VanDersie]

Thanks for the heads up. This datasheet came from Amy at Docan Power. That is really not inspiring confidence! Especially given the recent reports of them re-lasering the QR codes.

1st, I won't discuss Docan Power, cuz it's my first time to hear this company.
2nd, There are a lot of repacked cells in the market, many suppliers even supply reprinted (QR codes） cells, and over 70% of these cells were EVE. If you are interested, you can PM me, I have a video.
3rd, From last May, EVE has imposed a new stipulation, they will print a "B" on their Grade B cell's QR code, but the suppliers have a lot of ideas to clean the "B" code, then reprinted a new (fake) QR code and sold the B cells at A prices.

 

[Alkaline]

What a silly but PIA problem to have, you would think after being exposed for using fake QR codes they would at least get something this simple right.

 

[pelicanpebble]

Since I did say I'd report back on our prior drilling and tapping. We have no drilled/tapped LF280K or LF304 cells. I did find some of our old LF280s, tap depth was 5.7mm. picture included. Placement of calipers obv do not indicate measurement direction, only for visual reference. Yes they are terrible calipers, but they are plastic for no shorting.
View attachment 152634

@zcskywire2 Thank you very much! I also really appreciate your effort!

Do you think the LF304 can be drilled to the same depth?

 

[pelicanpebble]

What a silly but PIA problem to have, you would think after being exposed for using fake QR codes they would at least get something this simple right.

Yeah, and it looks like Docan has absolutely no intention of delivering replacements. Amy seriously suggested I pay for shipping the faulty cells to and from China so they can re-weld some new studs! Delay: 4 months.

 

[pelicanpebble]

@zcskywire2 Thank you very much! I really appreciate your effort! Sorry it took me a while to reply.

Do you think the LF304 can be drilled to the same depth?

@peacefulcurrant Sorry, I hijacked your thread, since I have the same problem.