Reattaching Cell Terminal - 62kwh module

[ekohn04]

Hi everyone,

After some very frustrating BMS issues, I discovered that the terminal of one of my cells had been pulled off of the cell stack.

Here is the module with the cover off

Here is the terminal in question

I have a traction wire attached to this terminal that's pulling away from the module. I assume this force, along with the vibration of the car broke off the weld. Although for factory welds these seem pretty bad, right? Anyways, I need a way to secure this terminal back in place. If I wanted to weld it, I'm not sure what material it is. Even if I had that information, I can't heat this area at all because it's making direct contact with a cell. By my reasoning, the problem is as stands:

I need to reattach and secure this terminal so its backside is making full contact with the cell stack. I need to find a way to do so without applying any heat. Does anyone have any ideas?

[arber333]

Hi everyone,
....

I need to reattach and secure this terminal so its backside is making full contact with the cell stack. I need to find a way to do so without applying any heat. Does anyone have any ideas?

How thick is the contact bracket material?
If it is thin enough you could try spot welding? And immediately after such weld you would need to cool the surface down...

I imagine the full width of the battery module is out of the size for laser chamber box?
Do you know someone which has access to friction stir welding machine?

[uhi22]

If the area where the red spacers are below would have sufficient space, a row of small screws (like 2mm diameter) could press the things together.

[jrbe]

Welding thick to thin can be very challenging.

Time and effort involved it might be cheaper to find a new stack section.

Then silicone? some spots to help eliminate the vibration for the rest of the modules.

[ginetto]

Hi everyone,
After some very frustrating BMS issues, I discovered that the terminal of one of my cells had been pulled off of the cell stack.

what was the issue shown by the BMS?

[ekohn04]

I imagine the full width of the battery module is out of the size for laser chamber box?

I'm not quite sure, I wouldn't even know how to look for someone with a laser welder in my area.

If the area where the red spacers are below would have sufficient space, a row of small screws (like 2mm diameter) could press the things together.

This is a really good idea, something I didn't even notice. I'm worried about depth with this approach, the spacer might not go all the way in between the cells. I will have to find some way to test how deep I can go without risking puncturing the cell.

Time and effort involved it might be cheaper to find a new stack section.

Stack section isn't possible as these are laser welded together. A new module would be the best idea, but I can't find anyone selling individual leaf modules for anything other than outrageous prices. If anyone knows where to procure a module that would be fantastic.

what was the issue shown by the BMS?

See this thread
viewtopic.php?t=5679

[arber333]

....
I need to reattach and secure this terminal so its backside is making full contact with the cell stack. I need to find a way to do so without applying any heat. Does anyone have any ideas?

Like i said... if you look closely you will notice there is aluminum material for last contact. Looks like + terminal as negative is usually copper.
In your case you could try to dissasemble the plastic under the contact and take it out with intent to put small alu plate under contact and another plate/angle above. You could then make 2 or 3 holes through alu plates and contact sheet. CAREFULLY!
Then use M5 bolts. Head from the underside which would fasten the upper alu angle so you can use the angled part as anchor to your terminal cable.
You will probably have to remove the red plastic to come underneath the terminal...

Another option would be using rivets and washers to fasten the termanal angle. Still you need to be really carefull when drilling. All debris needs to be vacuumed so not to cause damage later on...

[ianlighting]

Hi everyone,

After some very frustrating BMS issues, I discovered that the terminal of one of my cells had been pulled off of the cell stack.

Here is the module with the cover off

IMG_1947.jpeg

Here is the terminal in question

IMG_1949.jpeg
IMG_1948.jpeg

I have a traction wire attached to this terminal that's pulling away from the module. I assume this force, along with the vibration of the car broke off the weld. Although for factory welds these seem pretty bad, right? Anyways, I need a way to secure this terminal back in place. If I wanted to weld it, I'm not sure what material it is. Even if I had that information, I can't heat this area at all because it's making direct contact with a cell. By my reasoning, the problem is as stands:

I need to reattach and secure this terminal so its backside is making full contact with the cell stack. I need to find a way to do so without applying any heat. Does anyone have any ideas?

I’ve just taken delivery of a 62kWh (well mine is labelled 60, but close enough) Leaf battery. I know I have 1 cell much lower than the others, according to LeafSpy. I just wondered based on you being ahead of me, and already taken some of the module apart, does it seem feasible to you to try to manually charge up a single cell? Or does the welded module case stop that kind of access?

[ekohn04]

does it seem feasible to you to try to manually charge up a single cell?

I don't feel confident telling you that this will work/is a good idea/won't damage your batteries. Your best option is to charge the whole pack with a BMS and let it take care of balancing the cells. However, I think you might be able to charge that individual cell. You would have to get a charger that is set at the correct voltage, and monitor the neighboring cells in case they discharge to the cell you're charging. Even though the batteries are welded in series, it matters where your lowest and highest potentials are placed.

For example, I can measure the voltage of individual cells on the cell stack with a multimeter depending on where I put my ground. If I leave my positive probe on the positive terminal of cell #10 and put my negative probe on the negative of cell #1, I will read the voltage of all 10 cells. If I then move my negative probe to the negative terminal of cell #10, I will only be reading the voltage of cell #10. This is how a BMS reads cell voltages. It's all about the reference point.

This means that if your charger was set at the correct voltage and was placed on the positive and negative terminal of only the cell that is low, you could probably charge that specific cell. Please do your own research on if this is a good idea and come to a conclusion on your own. If you have more questions please post a new topic in the Nissan board.

[ianlighting]

I don't feel confident telling you that this will work/is a good idea/won't damage your batteries. Your best option is to charge the whole pack with a BMS and let it take care of balancing the cells. However, I think you might be able to charge that individual cell. You would have to get a charger that is set at the correct voltage, and monitor the neighboring cells in case they discharge to the cell you're charging. Even though the batteries are welded in series, it matters where your lowest and highest potentials are placed.

For example, I can measure the voltage of individual cells on the cell stack with a multimeter depending on where I put my ground. If I leave my positive probe on the positive terminal of cell #10 and put my negative probe on the negative of cell #1, I will read the voltage of all 10 cells. If I then move my negative probe to the negative terminal of cell #10, I will only be reading the voltage of cell #10. This is how a BMS reads cell voltages. It's all about the reference point.

This means that if your charger was set at the correct voltage and was placed on the positive and negative terminal of only the cell that is low, you could probably charge that specific cell. Please do your own research on if this is a good idea and come to a conclusion on your own. If you have more questions please post a new topic in the Nissan board.

Appreciate your thoughts. My question was as much about how accessible the individual cells were within the 62’s modules. I haven’t seen clear photos of the cells terminals to know if it was physical possible to access them. But I will find out when I get my lid off soon.

[Bratitude]

Appreciate your thoughts. My question was as much about how accessible the individual cells were within the 62’s modules. I haven’t seen clear photos of the cells terminals to know if it was physical possible to access them. But I will find out when I get my lid off soon.

Just trickle charge it through the bms cell taps….

[arber333]

Hm... i am thinking about this further...
Can you tell what kind of material is that contact made off? If it copper or nickel? You can check if it is nickel with a small magnet.

If it is nickel you can spot weld several nickel strips which you can use to anchor your main contact to.
Mind you you would need to spot weld a lot of nickel strips to get equivalent contact surface.
I recommend welding from 2 sides on the inside to make dual contacts and then spot weld that to a vertical copper sheet with appropriate holes for bolting....

[ekohn04]

You can check if it is nickel with a small magnet.

It looks like it's probably nickel plated copper, it's not magnetic. I was thinking it might be feasible to drill a series of divots in the part of the terminal that's pulled away from the cell stack to reduce the thickness in those areas, and then spot weld in those divots. That would hopefully give me the contact I'm looking for, and I can find other ways to secure the terminal to ensure the spot welds don't break. What do you think about this idea?