98' Charging issue

[niccaleb112602]

Volt gauge is acting odd. Start up vehicle. Volts are +13. Upon driving around awhile, when I come up to a stop sign and apply the brakes, the volt needle will plunge rapidly under 13 volts. Now this is in the day time with no accessories on. I just sat in the driveway at idle and watched the needle move around like pulsing. I can shut off the ignition and restart the car and everything goes back to normal for awhile. Then it starts acting up again.

[maxwedge]

Have the alt out put checked. Make sure all the battery cables are clean and tight.