[boba8523]

Hi guys,

I'm trying to disconnect the ground negative battery in the trunk of my 2015 m235i. The battery is not stationed on the right hand side of the trunk but rather where flat tires are at.

Anyways, I tried disconnecting the black cable that my finger's pointing at using a 10mm socket, and it created sparks as I was pulling the cable...

To my knowledge, ground isn't supposed to create sparks as it's not "hot", am I getting the correct ground cable?

Can anyone please tell me where the ground cable is?

[_bdiddyb_]

That big negative sign next to the post tells you it's the ground. You are booting up the computer when you close the circuit. I see this in my car too when I pulled the negative to work on it.

[boba8523]

Originally Posted by _bdiddyb_

That big negative sign next to the post tells you it's the ground. You are booting up the computer when you close the circuit. I see this in my car too when I pulled the negative to work on it.

So my finger's pointing at the correct negative cable and the spark is normal? Just never had spark happen in previous cars so it scared me a little...

[cryptocar]

It definitely can spark. It used to always spark on my 67 mustang but I swapped the battery and cables because the connections were corroded a badly. Now nothing. On my F30 I get sparks if I ever remove or install the battery terminal connection too sharply/quickly. Be gentle and smooth you'll lessen the chance of sparks. Also I always wear gloves.

Also you need to remove the connection at the Battery terminal to the the ground to the car, not the ground connection at the frame grounding point. If you do that and then the ground cable still connected to the battery can just fall into contact with any metal in the car and suddenly the battery is reconnected and there's voltage throughout the system again which is dangerous.

[boba8523]

Originally Posted by cryptocar

It definitely can spark. It used to always spark on my 67 mustang but I swapped the battery and cables because the connections were corroded a badly. Now nothing. On my F30 I get sparks if I ever remove or install the battery terminal connection too sharply/quickly. Be gentle and smooth you'll lessen the chance of sparks. Also I always wear gloves.

Also you need to remove the connection at the Battery terminal to the the ground to the car, not the ground connection at the frame grounding point. If you do that and then the ground cable still connected to the battery can just fall into contact with any metal in the car and suddenly the battery is reconnected and there's voltage throughout the system again which is dangerous.

Where is the connection at the battery to the ground of the car?

[cryptocar]

Originally Posted by boba8523

Where is the connection at the battery to the ground of the car?

You're pointing at the connection of the cable to the chassis. Follow that black cable up to the battery and loosen the 10mm nut enough that the wire terminal clamp can be slid upwards and off of the battery terminal post next to the (-) sign. Set the cable aside, I generally stow it down low in that compartment so that it doesn't spring up anywhere.

[boba8523]

Originally Posted by cryptocar

You're pointing at the connection of the cable to the chassis. Follow that black cable up to the battery and loosen the 10mm nut enough that the wire terminal clamp can be slid upwards and off of the battery terminal post next to the (-) sign. Set the cable aside, I generally stow it down low in that compartment so that it doesn't spring up anywhere.

Thank you so much!

[boba8523]

Originally Posted by cryptocar

You're pointing at the connection of the cable to the chassis. Follow that black cable up to the battery and loosen the 10mm nut enough that the wire terminal clamp can be slid upwards and off of the battery terminal post next to the (-) sign. Set the cable aside, I generally stow it down low in that compartment so that it doesn't spring up anywhere.

I've loosened the nut enough to the point where the bolt is now moving too when I tighten/loosen...

But the terminal clamp still can't be slid upwards and off. It can rotate left and right though. I've tried "opening" up the clamp but it wouldn't budge either.

Do you know what seems to be the issue?

And how do I tighten the nut now that the bolt is loose too?

[cryptocar]

Originally Posted by boba8523

I've loosened the nut enough to the point where the bolt is now moving too when I tighten/loosen...

But the terminal clamp still can't be slid upwards and off. It can rotate left and right though. I've tried "opening" up the clamp but it wouldn't budge either.

Do you know what seems to be the issue?

And how do I tighten the nut now that the bolt is loose too?

You just need to push the square head bolt up into its proper position against the clamp while tightening. Tension will hold it in place once torqued down just a little.

[Jeff@TopGearSolutions]

Originally Posted by boba8523

I've loosened the nut enough to the point where the bolt is now moving too when I tighten/loosen...

But the terminal clamp still can't be slid upwards and off. It can rotate left and right though. I've tried "opening" up the clamp but it wouldn't budge either.

Do you know what seems to be the issue?

And how do I tighten the nut now that the bolt is loose too?

You need to pull up, it will likely take some force.

Wiggle and pull up.

You can stick a flat head screw driver to widen the opening but make sure not to touch the screw driver to anything else on the vehicle or battery.

[Earthmaster]

I had this problem too everybody is right push the bottom up and and then unscrew it. BE CAREFUL don't be like me and fry your DME lol.... just don't tap the battery once you get it off and slide it carefully on and off or your will send voltage and spark stuff. just go slow as hell.