Unable to secure red terminal on 12V LVB

[gordonf238]

I've replaced about a dozen batteries in my relatively short life. I was going to attach eyelet terminals to the LVB for quick voltage check and charging if ever needed. After loosening the bolt holding down the positive terminal, it's seemingly impossible to re-secure it. It seems to be a free-spinning, permanently attached bolt that will loosen, but for the life of me, I can't reattach it.

If anyone has any ideas, I'm all ears

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[louibluey]

If you still have everything apart, could you post a picture of the other side (the lower side near the battery) if it's convenient? It would be interesting to see the mechanism that is supposed to tighten the pos clamp against the battery post.

I would pull mine again to have a closer look, but I think I had to pull the frunk tub every time I removed the positive terminal. Did you pull the frunk tub, or were you able to remove it without pulling the frunk tub?

I have an extra BMS (the negative terminal) on my desk now, but I think (?) the clamp tightening mechanism is different. I have been meaning to post some detailed pix of the BMS and ground cable for general interest.

 

[gordonf238]

Thank you.

I can remove the whole terminal (thereby disconnecting power to the vehicle).

I can't turn it around due to the sway bar. However, my fingers can't feel anything underneath. Just a smooth metal. I tried using a flat screwdriver to push the sides in but the bolt just won't latch. Keeps spinning in place.

Really quite silly to be honest, as I'm just about out of patience. The last thing I want to do is drive it to the dealership and look like a completely dummy.

But without the terminal secure, the car isn't really safe to drive as any large bump can cause that terminal to just pop off.

I'm just scratching my head here.

 

[louibluey]

Thank you.

I can remove the whole terminal (thereby disconnecting power to the vehicle).

I can't turn it around due to the sway bar. However, my fingers can't feel anything underneath. Just a smooth metal. I tried using a flat screwdriver to push the sides in but the bolt just won't latch. Keeps spinning in place.

Really quite silly to be honest, as I'm just about out of patience. The last thing I want to do is drive it to the dealership and look like a completely dummy.

But without the terminal secure, the car isn't really safe to drive as any large bump can cause that terminal to just pop off.

I'm just scratching my head here.

I'm definitely curious now, curious enough to pull the frunk tub, that probably takes about 1/2 hour. I vaguely remember being able to lift the pos terminal; well I have changed out the LVB three times during different LVB experiments.

I should be able to get some snapshots what the tightening mechanism is (unless anyone else already has their MME taken apart already tonight?)

Probably (WAG) either it is not seated properly on the pos battery post, something fell off the bottom, or the threads are stripped somewhere. But, I do not remember how the pos terminal clamp works without looking at.

Or, maybe the lower threads, whatever they are, are just a bit too low to re-engage? Can you slide your finger under there to see if there is something to just push up a bit to engage? (that is really a wild guess, I'll go take it apart and have a look.)

 

[dtbaker61]

I've replaced about a dozen batteries in my relatively short life. I was going to attach eyelet terminals to the LVB for quick voltage check and charging if ever needed. After loosening the bolt holding down the positive terminal, it's seemingly impossible to re-secure it. It seems to be a free-spinning, permanently attached bolt that will loosen, but for the life of me, I can't reattach it.

If anyone has any ideas, I'm all ears

I'm sorry to hear you are having problems with the terminal.... I have not pulled it, so I cannot really help other than to suggest a mirror underneath to see if there is a nut spinning......

However, I would also caution against using the LVB terminals for charging.... documentation warns against this because it 'probably' can mess up the sensors that are counting cycles, amp-hours, and such. Additionally, as you have discovered, accessing the POS terminal, is a PIA, and pretty dang close to the metal support running across the motor bay, and shorting from the POS terminal to the bar would be unpleasant for all concerned.

Any voltage checking, LVB charging, etc can more easily be done via the official LVB connection points, which are aproximately under the stamped + and - marks on the cover..... easily revealed and accessed with a 2" hole saw, or more slowly and painfully accessed by removing the back and side 'beauty covers'

 

[gordonf238]

Okay, so a brief update. After about an hour, I was able to see inside the terminal. There is a nut with notches, so as to prevent the bolt from coming out completely (understandable). While I was loosening the terminal bolt, the notches must have stripped. I can see the bolt attached to the nut inside the mechanism, but they're both spinning together and stuck. I've tried sticking a screwdriver in there to (hopefully) catch the nut and stop it in place, so that the bolt would latch, but no luck. No way around this aside from replacing the whole terminal assembly part. For now, the terminal is snug on the battery, but can pop-off anytime. I wouldn't consider it safe to drive.

Pretty bummed. The battery is made in China, and the terminal probably too. Really poor workmanship here if you ask me.

Now I'm off to dig through parts for this vehicle to hopefully find one.

 

[louibluey]

Thank you.

I can remove the whole terminal (thereby disconnecting power to the vehicle).

I can't turn it around due to the sway bar. However, my fingers can't feel anything underneath. Just a smooth metal. I tried using a flat screwdriver to push the sides in but the bolt just won't latch. Keeps spinning in place.

Really quite silly to be honest, as I'm just about out of patience. The last thing I want to do is drive it to the dealership and look like a completely dummy.

But without the terminal secure, the car isn't really safe to drive as any large bump can cause that terminal to just pop off.

I'm just scratching my head here.

Okay, I got it all apart. The mechanism is still embedded in the black plastic, but I think I see what the problem could be. You are not going to be able to fix it from underneath by pushing up because the black plastic cover blocks the bottom.

There is a steel plate at the bottom either with threads or a threaded part like a PEM nut (a round steel nut embedded in a flat part). The way it is supposed to work is that there is some intentional distortion of the bottom of the screw, so it is supposed to stop before coming all of the way out. Possibly you inadvertently unscrewed it past the stop. Or, the threads are gone, stripped, lets hope that is not the case.

So, you need to lift up that plate somehow with the threaded part, so the screw can re-engage the threads. You might be able to make a little tool by bending a small right angle arm at the end of a paper clip. Then, from the pictures, if you can gently lift that lower plate, and gently turn the screw, being very careful not to cross thread, you might be able to re-engage the lower plate.

The steel plate with the threads is the same as the part that comes out on one side and looks rough on the top edge, I think it was the back, may edit more.

I hate to mix work with pleasure, but there are really helpful drawings in the patent (see pics below and here is the google patents link).

Okay, so 1) hopefully the screw/bolt just inadvertently came out of the bottom plate, 2) unlikely, the threads of the screw are stripped, or 3) most unlikely, the threads on the steel plate are stripped.

I'm guessing you just backed it out too far.

 

[gordonf238]

Okay, I got it all apart. The mechanism is still embedded in the black plastic, but I think I see what the problem could be. You are not going to be able to fix it from underneath by pushing up because the black plastic cover blocks the bottom.

Lou,
Wow, thank you for all those photos and the write-up. You are indeed correct. I had to twist the metal terminal out of its plastic housing in order to see and access the nut that's lodged in there. You are correct, the treads are indeed stripped. I can see the nut attached to the bolt between a washer and another, larger metal piece at the bottom holding the whole thing together.

Unfortunately, by bending the terminal out of its plastic housing, it's now proving difficult to squeeze it back in. Nothing I have tried would get the nut to stop spinning. Which is odd because I didn't use an impact wrench, just a small hand wrench with a socket to loosen it.

I don't believe it's repairable. I believe the only solution is to replace the part (if I can find it). So far my search is only yielding a part for the negative battery terminal.

 

[louibluey]

Okay, so a brief update. After about an hour, I was able to see inside the terminal. There is a nut with notches, so as to prevent the bolt from coming out completely (understandable). While I was loosening the terminal bolt, the notches must have stripped. I can see the bolt attached to the nut inside the mechanism, but they're both spinning together and stuck. I've tried sticking a screwdriver in there to (hopefully) catch the nut and stop it in place, so that the bolt would latch, but no luck. No way around this aside from replacing the whole terminal assembly part. For now, the terminal is snug on the battery, but can pop-off anytime. I wouldn't consider it safe to drive.

Pretty bummed. The battery is made in China, and the terminal probably too. Really poor workmanship here if you ask me.

Now I'm off to dig through parts for this vehicle to hopefully find one.

I wonder if guided by the drawings in the patent (understand the nut may be different), if it is possible to take that portion apart?

Also, if you do not have a tap and die set, you could probably get the correct tap and/or die at Lowes, Home Depot, or some place like that, or order from a supply house.

If you didn't already pull the frunk tub, consider pulling the frunk tub to get better access. There is a video here on how to pull it. The first time, will take some time. After many times, it takes about a 1/2 hour.

Frunk removal, access to 12 V battery and to under hood fuse box - VIDEO by @Benjamin Kegele

Okay, curious satisfied, I am going to grab some supper. Good luck!

 

[gordonf238]

In your schematics, Fig. 1, Part 60 - That's where the nut is attached to the bolt. It seems to be missing from the drawings you shared. If the bolt is supposed to latch into Fig. 2B part 50, then it's definitely stripped and isn't catching it.

I would need to remove the whole front, including the sway bar, as well as the battery to better access that portion of it.

I wish I had more time and patience for this. Wife needs the car daily, so I'm scrambling to get her a rental in the morning while I figure this out.

 

[DevSecOps]

@louibluey I would like to thank you for going out of your way to help the OP. That was obviously something that took you time and although I don't have any plans on taking the LVB out I felt it necessary to thank you for the time in performing the tear-down and documenting the results.

 

[louibluey]

In your schematics, Fig. 1, Part 60 - That's where the nut is attached to the bolt. It seems to be missing from the drawings you shared. If the bolt is supposed to latch into Fig. 2B part 50, then it's definitely stripped and isn't catching it.

I would need to remove the whole front, including the sway bar, as well as the battery to better access that portion of it.

I wish I had more time and patience for this. Wife needs the car daily, so I'm scrambling to get her a rental in the morning while I figure this out.

Understood, but you only need to take out the frunk tub (a big job the first time). I have never needed to remove the structural bar.

Also, there is a little green/red plastic part over on the right side that disables the HV. It is good practice to open it whenever removing a clamp from the LVB because it turns off, or prevents the DC/DC converter from coming on.

This is in the "open position". It is good to never remove either terminal from the LVB without first opening this interlock switch. I thought it was silly at first, but now understand why they want you to open it (to protect the DC/DC converter). This is under the right side removable panel.

 

[louibluey]

@louibluey I would like to thank you for going out of your way to help the OP. That was obviously something that took you time and although I don't have any plans on taking the LVB out I felt it necessary to thank you for the time in performing the tear-down and documenting the results.

Thank you.

 

[gordonf238]

Well, found the part. Definitely not a small piece to replace. Looks like it's the entire cable assembly. I'll try to call the local mechanic to see if they can accommodate me.

 

[gordonf238]

Understood, but you only need to take out the frunk tub (a big job the first time). I have never needed to remove the structural bar.

Also, there is a little green/red plastic part over on the right side that disables the HV. It is good open it whenever removing a clamp from the LVB because it turns off, or prevents the DC/DC converter from coming on. I will go grab a picture of it (standby).

Thank you! Really, for going above and beyond.

I feel bad wife having to put all 4 kids to bed by herself while I waste time on something that should have taken me 5 minutes.

I did spark the battery once or twice, after which I've disconnected the negative terminal and taped it off. Really should've done that from the beginning, I just didn't think it would turn into a surgery.

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