Out on the actual Battery you will get a better reading. nothing on 12vd or higher 12.60ish is a good reading.

 

A battery should read between 12.47 and 12.6 if it's fully charged and in good shape.
But that doesn't mean a battery that reads inside that range is OK, it could still have issues.

 

The car monitors the charge status and backs off the voltage once it's full up.

 

Float happens around 13.vdc

 

Your plugin meter is showing the charge rate while driving. As fishycomics suggested, verifing battery voltage at the battery itself before you start the car is a better indication of the battery itself. Or take it to an auto store that checks batteries, which is usually a complimentary service.

 

Read this...

https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1011&context=auto_pres

 

I have an app running on the head unit that does the same readings. 42mos and if the battery has been on a charger the voltage is 12.5 or something. When I start up and drive without the charger the battery voltage says 14.4 or so. That article was a nice read too.

 

What your seeing are different reading. 14.4 is the alternator charge, . if you want to see more get an Ammeter that sees the actual load and what they will do as exactly what @3hondas3 suggested and I totally agree with him!

 

Seeing your vehicles charging system sitting at 14.5 vdc simply means that the vehicle has detected the battery is not fully charged and will continue to apply 14.5 until it detects the battery is fully charged (via a current sensor on the ground side of the battery, NOT voltage). The linked white paper above about Honda's dual charging system explains all the whys and what-fors of a Honda charging system.

If you drive only once every few days or so.. I can totally embrace the fact that your vehicle may not detect the battery as fully charged for some time... perhaps 30 minutes or so of driving. Also.. it is winter time, and ambient temperatures do affect battery chemistry and battery chemistry does affect actual measured battery performance. This is why modern battery smart chargers/maintainers have ambient temp sensors in them... as they need to change the charging profile they present to the battery under different ambient temperatures. For example: I generally see my vehicle batteries show stronger test results in summer compared to a chilly morning after the vehicle has been sitting for days.

VOLTAGE read across the power bus DOES NOT tell you anything about the general health of your battery. For that you need to have the battery properly load tested at a auto parts store, or you can do it your self at home with one of the popular low cost hand held battery testers.

You can, with your vehicle parked and turned off, and the hood latch popped, followed by a 5 minute wait time (to let the battery voltage to recover from the sudden drain from the vehicle power up sequence when you either open the drivers door or pop the hood latch). The power up cycle from popping the hood will also bleed off any float charge from having just been driven under charge. After 5 minutes.. read the voltage across your battery, and it 's actual state of charge would be generally reflected as follows:

Thing is.. state of charge (which is what the table above reflects), does not tell the whole story of your batteries state of health. You also need to have it tested to determine it's CCA capacity (actual), that it charges properly, and that it has the expected low internal impedance (which is generally what limits a batteries CCA). Note: Temperature DOES affect results from a battery test... so if being tested in cold winter temperatures, be advised that the battery will test lower than if it is 70+ degrees out for CCA, and probably reserve capacity as well.

 

I have a volt meter plugged into my 12V accessory port. My battery is about 18 months old. When the battery was new the volt meter read 14.4V after I started the motor and would slowly go to 12.4V after driving for a while. Now the voltage stays at 14.4V all the time. Does that mean my newer battery is going bad?17 CR-V

The battery is an energy storage device.
Its capacity or state of health is determined by the voltage and the current it can produce at temp.
The Honda smart charging system can be an indication of the state of the vehicle's load and battery.
If the other load is as the same as before then the battery may need to be looked at.
I always suggest testing before replacing. Except for certain situations.
State of health for the battery should be done thru load testing as others have said.

Newer battery doesn't mean better battery.
And if is failing at 18 months then have it checked out at the place of purchase
Warranty should help cover some or all of the cost for replacement.