90accord

I have a 2000 Cherokee sport. I start it this morning and start driving down the road and the CD player starts flashing on and off then i look at the dash lights and you can see the mileage numbers getting dimmer and brighter and then my check gauges light comes on and the voltage gauge is pegged at 19volt's. so i pull over turn it off and restart it and everything it fine. I drive 10 or so miles down the road and it starts it again so i pull over turn it off and restart it and everything is fine again. Ive checked the battery connections The ground was a little bit loose but not floppy falling off loose. checked the alternator connections all tight.