2018 Yukon...just bought...80k on the odometer...
The voltage is normal then during a drive it drops to 12.4 volts...it stays till you turn the ignition off. Had it checked with a meter ...same reading..battery doesn't seem to drain...
Any ideas? Alternator failing ?
Thanks in advance
normal too a certain extent, if it is constantly all over the place or often "low" it could be indicative of a battery getting weak, they don't last forever.
you can grab a cigarette to usb adapter with a volt reading on it for cheap off of amazon/ebay and kind of watch to see what it does, the "volt" gauge in the cluster is just a dummy light of sorts.
so essentially the question is "how old is the battery" a fresh battery tends to hang around the middle of the gauge a lot more than a older battery
the only way to say for sure is to use a scanner to see if the RVC system is operating properly with the battery, if the battery is not charging properly the RVC systems thinks it is and doesn't know any different based on the reading thru the sensor.
for instance if you have the headlights on and wipers on and the alternator is not getting commanded to bump the voltage up, it could be because the sensor is getting incorrect feedback from the battery state of charge. OR it is kicking the voltage up but the battery has some resistance and you end up with a gauge on the low side anyway. This may also be reflected in the RVC system with a scanner. For instance it can say "economy mode" active, when it shouldn't be.
it is a system they started using to get EPA credits, supposedly it saves you .01 mpg, or something ridiculously low.
none of the above means run out and buy a battery, if it is working and not going dead then your good to go if it is the battery they tend to give up the ghost when the weather changes either in the spring when it warms up or in the fall/winter when it gets cold
