I typically see 14.2 volts on my Torque Pro app when I'm driving. This morning, I was driving around and noticed it running @ 14.1. Later in the afternoon it was 13.8 volts sitting at t stop light and gradually got back up to 14 volts on the way home. Battery is strong and always on a maintainer (I know someone will ask). Voltage @ the posts with terminals disconnected was 12.94 volts when I got home. 2 hours later, still 12.94 volts.

I think I'm either catching something beginning to go south early or maybe have just never noticed a fluctuation before. Any thoughts?

 

Sort of seeing the same thing.
A week ago Saturday, I finally got a chance to take the car out for some driving around town for most of the day. And I noticed that my voltage was reading 13.8 via my HKS Camp-2 on-screen display. Car had been on a maintainer all winter, and the battery was a new AGM last year.
However yesterday, when I took the car to work, the voltage was again back up to 14.2 while driving my short hop to work.
Maybe just slow to wake up from the winter nap?

 

Thank Ken. Good to know I'm not alone and hopefully it's nothing. For those of you who have voltage selected on Torque Pro, are you displaying Volts CM (control Module) or Volts OBD?
I have CM currently but have used OBD. They read differently on my car

 

If the battery is fully charged, the charge voltage will drop back to the float charge which is typically about 13.6-13.8v. If the charge voltage stays in the 13.6-14-6 range, all is most likely as expected.

Cars with the battery monitoring system will periodically let the battery voltage drop to 12.2v and then bring it back up to full charge. That is worrying when you first see it happening and are not expecting it

 

There are 2 different charging systems in the X150. The 4.2 cars charge differently then the 5.0 cars. Most of the posts of the 4.2 cars seem to run all day at 14.2 Volts while the 5.0 cars seem to run at 13.5 volts. I just had my battery of 5 years replaced in my 5.0 and also had the BMS reset along with the system checked and verified. New battery was 100% charged prior to installation. Normal driving my voltage gauge reads at 13.5 Volts but when you lift off the go peddle ans coast the voltage will spike up to 14.4 volts but as soon as you get back on the throttle it goes back down to 13.5 v. I was under the impression that the 4.2 cars would stay at 14.2 under both conditions. Oh you are correct on the recondition cycle that takes the 5.0 cars down to 12.5 volts periodically. I don't believe the 4.2 cars do this so any prolonged voltage below 14 volts should be questioned . My 2 cents and understanding.

 

You may well be correct but that would surely mean that the battery is being overcharged when it is fully charged - not something I would expect that the engineers would have done?

 

Agree and maybe some 4.2 owners who watch their voltage can chime in and tells us what they are running.

 

According to the Workshop manual...

 

Guy although it speaks to a 14 V system it does not describe the charging cycle or normal running voltage . Maybe others can comment on what voltages they are seeing . What I always found interesting was all of my imported cars used to run at about 13.8 volts all of the time while my domestic cars/trucks used to run at 14.2 volts all of the time until I got my 2016 Chevy pickup. it runs between 12volts to 14.5 volts with 14 being the sweet spot.

 

Did I interpret it incorrectly?
"

1. The ECM monitors the load on the electrical system via PWM signal and adjusts the generator output to match the required load. The ECM also monitors the battery temperature to determine the generator regulator set point

1. The Generator has a smart charge capability that will reduce the electrical load on the Generator reducing torque requirements
   

I interpret it as 'variable' or 'dynamic'.

 

It sounds that way but as I mentioned I have not seen to many post on the 4.2 cars that run at under 14.2 volts. So it would be interesting to see what folks say. As to the 5.0 cars they introduced a BMS (battery monitoring system) that describes the function in the manual. This is not on the 4.2 cars.

 

Hi,
In my experience a system voltage of 14.0v to 14.5 is just ideal, while 13.5 is okay to marginal. Our '07 4.2 can sit for periods without a maintainer, though it does have a cheapy for longer times and the winter.
BMW seems to have a bigger problem with their smart charging stuff..
http://www.roadandtrack.com/car-cult...ns-bmw-n63-v8/
Twin turbo V8, who would care about a fraction of a mpg??
Sometimes I long for simple.
Regards

 

On my 06 str....4.2sc....i see 13.7 to13.9 as charge voltage after it settles in...i have smart charge also....great system as long as the alternator keeps churning....where ever the voltage can be read by my modis scanner, that is what i always see, regardless of load....except of course after startup ,where it can go 15 volts for a short while

 

Funny I had to take my 2016 chevy pickup out today so I plugged in my digital volt meter. Started up the truck and the truck gauge went to a hair over 14V and the digital read 14.4V so it was in sync. Had a 10 mile drive and about half way both gauges dropped. The instrument panel gauge went down a notch (about 1/4") and the dig. gauge read 12.7 Volts. Stayed that way until end of trip. Restarted on way home and same results . 14.4 - 12.7 Battery is 2 1/2 years old.

 

Thanks for the replies guys. My 07 has consistently read 14.2 volts and I have never seen it drop below that. I'm not saying it hasn't. I just haven't noticed it. I took a quick grocery run today and it read 14.2 the entire 2 mile drive there and back but dropped to 14.0 when I pulled in the drive.
Again, not sure this is even a problem as technically it's charging the battery. I'll also check the tightness of the of the accessory belt and tensioner (lazy on my part.) I would think this is the most likely culprit vs generator.