12 volt battery voltage difference

[BretMaverick]

Bought a digital battery voltage tester. Inserted it into the 12 volt socket and it read 15.25 volts. measured the voltage of the battery and it measured 12.25 volts. Why is there a difference in readings? How is the 12volt socket connected to the battery?

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[Darnon]

Bought a digital battery voltage tester. Inserted it into the 12 volt socket and it read 15.25 volts. measured the voltage of the battery and it measured 12.25 volts. Why is there a difference in readings? How is the 12volt socket connected to the battery?

You should be seeing about ~15.2 at the battery then. I'd use whatever voltmeter you're checking the battery with to double check the 12V socket, the battery, and also at the battery cable connection point under the hood. Being built late March/April '22 yours should be after the window of bad battery cables.

 

[Ozarkbeard]

... and also at the battery cable connection point under the hood

The under-hood "jump point?"

 

[Hot Runr Guy]

Since the 12V socket is only live when the vehicle is running, was the truck shut off when you checked at the battery?

HRG

 

[BretMaverick]

Since the 12V socket is only live when the vehicle is running, was the truck shut off when you checked at the battery?

HRG

 

[BretMaverick]

the voltage at the battery was checked when the Maverick was shut off.

 

[Silver23]

the voltage at the battery was checked when the Maverick was shut off.

there is your answer. with truck on it is charging the battery so you see a higher voltage.
Mine will show about 14.9 on, and around 12.3 off.
The accessory point is in a since directly connected to the battery through a relay and a fuse but only when the truck is powered up.

 

[The Real Maverick]

I've noted three modes:

key off: 12.x volts

key to accessory: 13.x volts

key to run, ready light on: 14.5 to 15.4 volts

 

[MetalsGeek]

I've noted three modes:
key off: 12.x volts
key to accessory: 13.x volts
key to run, ready light on: 14.5 to 15.4 volts

Isn't it interesting that the documentation on modern vehicles is so egregious that we actually have conversations like this, and simple facts on the underlying design never come to light? Ex: I'm pretty sure there must be some way to manually start and idle the hybrid's engine for testing, but this is somehow a closely guarded secret.

 

[svogt302]

Since the 12V socket is only live when the vehicle is running, was the truck shut off when you checked at the battery?

HRG

12V socket is alive when the car is shutoff for a period of time depending on the current battery state of charge.

 

[The Real Maverick]

Isn't it interesting that the documentation on modern vehicles is so egregious that we actually have conversations like this, and simple facts on the underlying design never come to light? Ex: I'm pretty sure there must be some way to manually start and idle the hybrid's engine for testing, but this is somehow a closely guarded secret.

There is a way. It is a secret. But not well guarded.

Chock the tires.
Put parking brake on.
Start hybrid engine.
Press "go" pedal if necessary.
Shift to "N".

The engine will run until it runs out of gas or until you put it in Park or until you turn the key off, whichever comes first.

 

[The Real Maverick]

There is a way. It is a secret. But not well guarded.

Chock the tires.
Put parking brake on.
Start hybrid engine.
Shift to "N".

The engine will run until it runs out of gas or until you put it in Park or until you turn the key off, whichever comes first.

In this mode the HV battery will NOT recharge. The HV battery will trickle charge the 12v as long as the HV battery is above 30%.

At 30% the HV DC/DC converter will stop charging the 12v battery to protect the health of the HV battery, and to reserve enough power to restart the truck.

The 12v alone will probably keep everything running until about 10 volts, but I've never tested out this aspect and don't intend to. So run time in "N" will be longer with accessories and lamps off, shorter with a lot of power draw on.

 

[MakinDoForNow]

I've noted three modes:

key off: 12.x volts

key to accessory: 13.x volts

key to run, ready light on: 14.5 to 15.4 volts

I have 4 modes (lariat)
Extended Accessory (dcdc converter active) am not sure but think voltage up to 14.4.

 

[Hot Runr Guy]

12V socket is alive when the car is shutoff for a period of time depending on the current battery state of charge.

Doesn't it shut off once you open the door (to go check at the battery)?

HRG

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