I've had some trouble in the past with getting a white buildup around the negative terminal of the battery in my rodeo ute. I have always been able to get it going again, but it has always been some fiddling around when it gets bad.

When this happened the second time I bought a new battery terminal and put it in the car. Ready for me to install it. However because the problem didn't come back I didn't end up getting it installed.

Yesterday I had the same problem. I park on a slope at work and there is enough electricity getting through the terminal to hill start it, which I did. However when I got home there wasn't even enough getting through to run the central locking. So I had to fix it.
This is the old terminal. Just an extension of the crimp that gets bolted around the battery post. It looks pretty rubbish for a factory part, but I guess it's worked for the last 10 years.

This is the new part. I just cut the strap off the crimp and left the main body of the crimp alone so all of the little wires would stay in one bundle. According to the packet this terminal is lead which is the same material as the battery post so there should be no compatibility problems there. What will be interesting is if the problem goes away, or if it moves to where the wires meet the new terminal.

Cheers,
Rex