Voltage gauge question

[zshowket]

Traditionally your voltage gauge shows you the voltage that your alternator is producing, and can show when your battery is in a charge mode or if you are using a lot of electronics. If your battery is charged then the voltage would read lower.

However, in the jeep gauge it shows Battery Voltage. So is this measuring the battery or the charge?

When I see 14.8 I am assuming that is what the jeep is producing to charge the battery. However, I have heard others mention the exact opposite.

Anyone know the truth to this?

Sponsored

 

[geem03]

I'm not sure. . but i know that my voltage gauge fluctuates from 12.9V to 14.8V.... is this normal?

 

[jlroman2]

I'm not sure. . but i know that my voltage gauge fluctuates from 12.9V to 14.8V.... is this normal?

Isn’t the 12v one is when the auxiliary battery—the smaller one— is the only battery on. And the 14.8v is the big one? That’s my guess

 

[geem03]

Isn’t the 12v one is when the auxiliary battery—the smaller one— is the only battery on. And the 14.8v is the big one? That’s my guess

I'm not sure... sometime's it reads 14.8V then it will drop to 12.9V for a while and then back up to 14.8V

If the ESS is on, it'll drop to 12V until the jeep starts up again.

 

[zshowket]

I'm not sure... sometime's it reads 14.8V then it will drop to 12.9V for a while and then back up to 14.8V

If the ESS is on, it'll drop to 12V until the jeep starts up again.

Well then, that is our answer. My ESS has not worked for over a month, that is why I have started watching the gauge. If yours drops to 12v when the ESS engages then that is your true battery voltage, everything above that is what the charging system is producing to operate the electronics and charge the battery.

This is one reason I am getting rid of the stock small battery and going with a dual battery setup.

 

[Jelllo]

Traditionally your voltage gauge shows you the voltage that your alternator is producing, and can show when your battery is in a charge mode or if you are using a lot of electronics. If your battery is charged then the voltage would read lower.

However, in the jeep gauge it shows Battery Voltage. So is this measuring the battery or the charge?

When I see 14.8 I am assuming that is what the jeep is producing to charge the battery. However, I have heard others mention the exact opposite.

Anyone know the truth to this?

Think of voltage like water pressure in a pipe. It doesn't matter where you measure it, it will be the same. Now when you turn off the pressure, or turn off the engine, then you are measuring battery voltage. You can't measure battery voltage accurately while the vehicle is running, because no matter where you check it, you are seeing charging voltage.

 

[geem03]

Well then, that is our answer. My ESS has not worked for over a month, that is why I have started watching the gauge. If yours drops to 12v when the ESS engages then that is your true battery voltage, everything above that is what the charging system is producing to operate the electronics and charge the battery.

This is one reason I am getting rid of the stock small battery and going with a dual battery setup.

I just thought the jeep would charge at 14-ish all the time it was running and not fluctuate. I get and it makes sense what you are saying about when the ESS is on, but i was troubled with the fluctuation when the vehicle was running.

With today's cars running off of computers and not old school voltage regulators, this may be normal for all i know...

 

[melendez69]

I'm not sure. . but i know that my voltage gauge fluctuates from 12.9V to 14.8V.... is this normal?

This is perfectly normal. There are a lot of good & informative reads on voltage & what the gauge displays.

https://www.jlwranglerforums.com/fo...attery-jumpstart-dangerous.42570/#post-943443
https://www.jlwranglerforums.com/forum/threads/low-voltage-on-the-3-6.23751/
https://www.jlwranglerforums.com/forum/threads/battery-voltage-driving-me-crazy.11219/

 

[Maverick909]

battery voltage and the voltage produced by the alternator are in sync. Alternator charges the battery and the battery is the main power connection for all of the electronics. therefore what the battery voltage gauge says tells you everything. at 14.6 - 14.8 your charging and running everything on the alt. when at 12.8 your atl has been opened up to allow just the battery to be used. this function allows the battery to drain a bit to keep the electrons moving and allows the battery to last a lot longer. could do a full detail of it but that will take to long. LOL. as long as your jeep starts its alllll good

 

[jeepdabest]

I'm not sure. . but i know that my voltage gauge fluctuates from 12.9V to 14.8V.... is this normal?

Very normal. You shouldn't be constantly in the 14s unless you are only on short trips.

 

[Redbaron73]

I did my first night drive in my jlur. I set the display to show voltage, and it remained below 12.8 the entire 40 mile trip while driving. When stopped at the few lights it would jump to 13.3-13.5 but as soon as I started driving again, it would drop.

Is this normal? For most vehicles, I would think I have a bad regulator.

I have the LED, tow package, 3.6L auto.


Edit:

I did search before writing, but continued searching and found this thread

https://www.jlwranglerforums.com/forum/threads/low-voltage-on-the-3-6.23751/



Guess it is normal.

 

[beaups]

The voltage is high when the smart alternator is engaged/charging (typically while braking) and low when it's disengaged (typically all other times unless the battery is below a certain threshold and/or the electrical load is over certain threshold).

Tldr typically "high" voltage indicates the battery is charging and "low" voltage indicates it's discharging.

Sponsored