if the battery is not holding the charge, chances are you might not be able to start your engine in the morning and or you can tell the starter in not that powerful, after parked all night.I can see that the alternator is charging but how is it that you know that the battery is holding a charge? After you turn the car off I assume?
bought from AmazonI have a 12v meter that just plugs in but. I like the one in the photo. Where was it purchased?
Usually the numbers to look for are 13.8 for running voltage and 12.6 for the resting voltage but the resting voltage can sag in cold weather without indicating a bad battery.