Battery Cables/VoltMeter?

Drive a 94 ford ranger, 5 speed. Last week on way home from work I noticed that the VoltMeter was up to the 18 mark in the positive, but would drop down to the 'normal' level while in neutral. Not an automotive expert by any means, but new the battery was pretty old so went ahead and replaced it hoping this might fix the problem.

Worked fine until today, started shooting way up into positive again while in gear...occasionally would drop back to normal...only to shoot up again eventually.

Truck seems to run fine, but not sure if I am doing any damage while driving it like this.

Replaced the alternator about a year and half ago, don't think that is it, as the problems were completley different when that went out.

Any suggestions? Is it simply a bad negative cable?

Faulty regulator? Bad cables can cause an overcharge situation. What happens when you turn on the lights? Have the system load tested.

if you have a voltmeter the battery should read 12 when off and no more than 14.5 while running. i would guess alternator going bad again. most part stores can test it for you.