Extra voltage

Is it a problem if the dashboard battery gauge reads 18+ volts while driving? The gauge rises and falls when I speed up or slow down to stop and bottoms out at about 12 volts when stopped. This didn’t happen prior to having another transaxle installed. Oh yeah, 1991 Chrysler New Yorker Fifth Avenue, 3.3 engine. Thanks.

There are a number of ways to go on this. Some people claim you can take your car to some place like Autozone, and they will check the alternator/battery. If it really is running up to 18 volts, that would seem to tell you.

If it is not really running up to 18 volts, then the dashboard gauge is defective, which may not need replaced if you don’t care.

sounds like things are not grounded right. Maybe they missed a ground attachment when putting things back together. You need a wiring diagram enabled diagnostic. It could be a ground to the computer from the voltage/charging circuit is off. It could be a problem if it means other computer based readings are off due to bad grounds.

The voltage regulator is bad. It may be internal to the alternator so it would need to be changed also. Having that much voltage charging the battery will damage it in short order so get this fixed ASAP.

BTW about 13.5 when running is correct with about 12V with the engine off.