I turned the key and heard a click almost immediately and the lights went out. All of them. I had just gone 6 miles and it ran fine. It sat for about 4 minutes before I went to try and move it and zap. I tested battery voltage and it reads 12.7 but drops to zero when I turn the key on. The battery is 6 months old. I first though fuse but why would a fuse cause the battery to drop to zero at the posts. Posts are tight and clean. I checked the connections under the seat and everything seems tight and normal. I would think that with the battery going to zero at the terminals with the key on something would be getting hot but haven't been able to locate it. HELP?

Thanks, Dan