Charge and run like crap

You want the quick & dirty way to install the relay?

Just mount it right next to your voltage regulator, and use the old sense wire as the relay feed, and ground it right there at the mounting screw. This will activate the relay, and you won't need to run any extra wires.

Then just pass you new sense wire through the relay and you're done. Took about 15 minutes for me to wire it in.