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resting battery voltage


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i own a 2011 edge and the resting battery voltage is always at or over 12.6 volts which is 100% charge level. my 2016 edge is always above 12.5 but never 12.6 volts as it should be. this is a new battery. trying not to obsess on this but .. does anyone else check voltages on their car battery?

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8 hours ago, gonesail said:

this morning i found it at 12.46 volts. that's only 80% charged with new battery. i did a few short trips yesterday.


It’s a 12 volt battery.  The alternator puts out over 14 volts while the vehicle is running but not all of that goes to the battery.  
 

What you should be checking is CCA as measured with a digital tester,  Voltage can be fine but it won’t have enough amps.

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1 hour ago, gonesail said:

.. resting voltage is definitely an indicator of battery health. and leaving a battery in a persistent uncharged state will lead to diminished battery performance.

quite right. 

but just to be clear, when you test resting battery voltage, that is supposed to be tested with ZERO load, (which is nearly impossible with it connected to the vehicle)

and keep in mind that some batteries top out at slight different voltage depending on conditioning and type (AGM vs flooded vs gel)

One of the better ways to test a battery is impedance and load testing. This gives a better metric of capacity vs state of charge, which is primarily what resting voltage tells you.

also, the computer (which runs the charge algorithm by directly controlling the alternator) is set to target something like 75% charge for fuel conservation purposes supposedly.

you can use forscan to change this value, though i don't necessarily recommend it

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one more thing, checking resting voltage in the morning means any small persistent drains have had the opportunity to siphon off a fair amount of power overnight.. 

effectively irrelevant drains can still pull a battery down over time.

and it is possible your battery is old and wearing out 

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7 hours ago, gonesail said:

.. resting voltage is definitely an indicator of battery health. and leaving a battery in a persistent uncharged state will lead to diminished battery performance.

Why not stop in at Autozone and get the battery tested as @akirby suggested?

The test will display the battery CCA capacity, cranking amps, and the vehicles charging system.

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On 6/20/2024 at 10:40 AM, gonesail said:

this morning i found it at 12.46 volts. that's only 80% charged with new battery. i did a few short trips yesterday.

What was it immediately after shutting down the engine, and how many hours did it take to drop from that number to the 12.46v ?

 

Did you do the BMS reset after installation of the new battery?

Is the new battery the exact same type and capacity as the original?

Edited by 1004ron
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  • 2 weeks later...

it's a new battery that is the recommended size for an Edge. i tried doing a BMS reset but not sure if it worked. i think i agree with those saying there are persistent drains with these vehicles .. therefore resting voltage is unfortunately deceiving.

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