Attatching the stripped wires directley to the battery posts by wrapping them around sounds a little sloppy, just my opinion. The connection won't be real good. I'm guessing that the lighter in the 1989 is an older one made before it was as common to use them for powering devices. I would try to find an adapter at a store like Radio shack that will let you use the charger without having to cut the wires. I would also look into whether or not feeding current back into the lighter socket is going to cause any problems, I don't know enough about it to say. Another option would be to cut off the adapter, and install some battery clamps/clips to the stripped wires. If you can find some clamps that attatch to the wires by wrapping the wire around a small screw built into the clamp, then tightening the screw, it will be easier to attatch the wires to the clamps. The other method would be to crimp the clamps onto the wires with a pair of pliers. Then attatch the clamps to the battery, positive , then negative. Remove negative then positive. I like to wear gloves when working with car batteries, in case there is any acid present, and because the terminals are made of lead. Anyone who knows more please add your $0.02...

Thanks for your advice John. I thought about getting an adapter, but still don't know if it would fit correctly in the lighter socket. Will definitely get clamps though. I was told by the owner who sold me the solar charger that I could easily connect it with an extension, as long as the wire are linked accordingly.

Kevin