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Dead Battery, Advance Auto Says Bad Alternator on 2020

Dgc333

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f you voltmeter is feeding off a 12v socket in the cabin, you need to add 0.2v to whatever you see to get an accurate reading of the voltage flowing into the battery.
It is powered off the fuse block. I realize that there is some voltage drop compared to reading directly off the battery and the gauge itself has some level of inaccuracy but that is really not important. The purpose of the gauge is to monitor for large changes from the norm that would require further diagnostics.
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Tom_C

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Apparently. My Ranger sits fallow in the garage this time of year, sometimes for a couple of weeks.
When I get into it there is a display notice about some sort of battery saver mode.
Always plenty of cranking juice, but the battery is now 5+ yrs old. ....time to make that battery/alternator multimeter check. ....or just wait until it struggles and give it a 50 amp boost jolt from my charger. Then replace it.
I have a 2020 and it started to lose it's mind. Lots of little electrical funkiness, but never failed to start. The last straw was it locking me out with the key fob inside the truck (which may or may not have been related, but seems sus)
 

rufanyia

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A 10v battery is definitely low, and that could point to more than just an alternator issue. I've seen cases where a bad cell in the battery itself caused similar symptoms. If the alternator was truly bad, you'd likely see the battery draining while driving. Might be worth double-checking the battery's resting voltage after a full charge and then again after sitting overnight to rule out a parasitic drain.
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