1999 Oldsmobile Cutlass Battery Cables

You need the correct cable and the tools that fit the bolts. Wearing safety glasses is a smart idea.

Use a 5/16" box wrench, or socket and ratchet to remove the negative cable first. If you don't do that first, you'll cause huge, dangerous sparks if the metal tools touch the positive cable and any metal part of the engine or body.

Next, remove the positive cable the same way. There will usually be two cables together on the positive terminal. The large one goes to the starter. That nut will typically call for a 15 mm wrench or socket, but it could take a different size. The smaller wire usually bolts to the under-hood fuse box, and will likely take a 13 or 15 mm socket.

You can safely connect the positive cable to the battery. Start the small bolt by hand to be sure it's not cross-threaded. Snug it down, but over-tightening can damage the threads in the battery. The last step is to reconnect the negative cable. Be aware that all batteries give off explosive hydrogen gas, and when you make the final connection, there's going to be a small spark. I like to blow over the top of the battery to disperse any hydrogen, but it rarely causes a problem.