1997 Jeep Laredo spike in voltage on gauge

There are diodes in the alternator that convert 3 phase voltage into DC voltage. If one or two of these diodes goes bad or comes loose, the voltage can spike to over 100 volts. When it comes to auto computers and other electronics, this is a "bad" deal. I wouldn't start it again until I changed the alternator. Just to give you an idea, there is an alternator kit you can buy for some vehicles that bypass's these diodes and run an ordinary electric drill off the output. Yours is the first case I've heard of in years, but it does happen. Hope this helps and thank you for the donation, Jim