12V battery connector bolt specification

[scrambler]

I want to connect a 12V battery monitor to the 12V battery terminals. To do that I want to attach a ring connector on the existing bolts of each terminal connector.
It looks like the bolts are 6mm bolts, but none of the nuts I try fit.
Does anyone know the specification (Diameter and thread) of the nuts that tightens the connector on the battery terminal?

Thanks

 

[mojo]

It would be worth searching alohart's posts - I can recall he altered the bolts on his car to (IIRC) make them less likely to fall off when removing the battery. But TBH I would be very surprised if a German company would have used anything other than a standard ISO metric bolt. I.e. standard M6. Standard spec is 6mm by 1.0mm, fine pitch would be 0.75mm, though I can't think of any reason why that would have used fine pitch in that application.

 

[EvanstonI3]

Mine is connected under the 10mm nuts on the terminals using the Spade Connector on the device. Still going after several years

 

[alohart]

It would be worth searching alohart's posts - I can recall he altered the bolts on his car to (IIRC) make them less likely to fall off when removing the battery.

Your memory is correct. However, I modified the top screw that attaches the battery hold-down bracket, not a bolt associated with the battery terminals where a 12 V system monitor would be attached.

I attached 12 V monitor leads to the battery cable clamp bolts under the nuts that tighten the clamps. It can be a bit challenging to keep the standard spade connectors in place while tightening the clamp nuts, especially considering the challenging access to the positive cable clamp.

Having ring connectors on the leads would have made this easier which I'm guessing is what @scrambler wants to do. However, removing the nut so that a ring connector could be installed is difficult because the bolt threads seem to be buggered near the ends of the bolts so that the nuts won't fall off should they loosen. Maybe that's why @scrambler thinks his nut isn't the correct size and/or thread. It can feel like the nut is being cross-threaded when trying to install it. As far as I know, it's a standard metric bolt and nut.

 

[maclaytodd]

The tip of the threads are swaged/slotted a bit to retain the nut so you will want to use a die nut to clean that up. I was able to force the nuts off using a little thread paste to get adequate clearance for a standard die nut. I've put a DC current meter (inductive (ring) type) on my 2014 Rex using ring terminals under the battery nuts.

BTW: I had to disconnect the battery negative at the chassis to get the current pickup over that wire/terminal. That involved taking out the battery and battery tray to get to that end.

Note: Always shut down the HV system with the green or orange safety interlink disconnect up front & on other side from battery when disconnecting 12V battery in order to avoid codes popping up.