Bad battery or ?

[klonestar]

Woke up to a dead battery today. Put charger on and only showed 10 volts at first. Cleaned and tightened connections then showed 11 volts. Charged and it only shows maybe 12.8 volts ...went for a ride got back and it shows 12.2 volts. Is battery shot? Thanks.

Ken

[Lodi Jim]

Read volts at battery, then start motor, read volts at battery again.
With motor running it should read 13- 14 volts. This is a good alternator.
If alternator is charging clean tight connections at battery, then that eliminates the alternator. Check ALL (yes, ALL) grounds; if you have a high power stereo, disconnect power to it and try again.

[klonestar]

With engine running im only getting max 12.8 to 12.9 volts using a multi meter on the posts with clean and tight connections. will check for grounds as well. That may well be the culprit due to condition of wiring lol. Its a stock 90' xj with a poor maintenence record before I got it.