3.6L charging voltage?

[Obviousbicycleco]

I just picked up my Jeep from the service department at the dealer because my Jeep died this past Sunday, leaving the kids and I stranded. After jumping it and still watching the voltage drop, we shut it off and had it towed in.

Dealer found both batteries were toast and the 150 amp fuse array was bad. The dealership stated they checked the alternator and that it IS charging. However, I’m left confused. My volt meter in the guages generally hovers around 12.7-12.8 volts. It will occassionally jump to around 13.8-14.1, then drops back to the 12.7-12.8 range.

Help me feel at ease! It just seems weird because every other vehicle I have had read out at around 13.8-14.4v all the time. Is my voltage regulator in the alternator toast and the dealership missed it too?

Thanks in advance for any of your inputs.

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[Pape]

This is odd, charged battery is 12.8 and charging voltage start arround 14v depending on the temperature. From my observations it never go below 13.5 while running and drop down to 12.8 while stop.

The number make sense to me but not the situation when they occur

 

[SonofaSeabee]

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[Vanburi]

Do some online searches. These things have smart alternators that are controlled by a computer. This in not the alternators of yesteryear.

 

[Obviousbicycleco]

Do some online searches. These things have smart alternators that are controlled by a computer. This in not the alternators of yesteryear.

These are the changes I was looking for. This helps. I will research. Thanks.

 

[Bob Burd]

12.8-14.5 is roughly the range the alternator puts out depending on how charged the battery is.

 

[RatZero]

When I was going through the electrical issues with my Gladiator and brought it to a local shop that specialized in Alternator/Battery/Wiring in Automotives they explained it to me like this.

It's a 12v battery. Normal no load voltage should be 11.9-12.8 if tested with a multimeter off the terminals. Under load after start and during normal conditions ie. car is moving should show 12.8-14.8 from a dashboard value which signifies the battery is recieving current sufficient to maintain charge under load. What you're seeing is the extra current of alternator + battery voltage OR the battery voltage (12v) and the extra 2v keeping the lights on and the radio blasting Taylor Swift.

If you see a dashboard voltage while moving under 12.1 or over 15, it would be an indication of a possible issue if it happens frequently.

 

[roaniecowpony]

I just picked up my Jeep from the service department at the dealer because my Jeep died this past Sunday, leaving the kids and I stranded. After jumping it and still watching the voltage drop, we shut it off and had it towed in.

Dealer found both batteries were toast and the 150 amp fuse array was bad. The dealership stated they checked the alternator and that it IS charging. However, I’m left confused. My volt meter in the guages generally hovers around 12.7-12.8 volts. It will occassionally jump to around 13.8-14.1, then drops back to the 12.7-12.8 range.

Help me feel at ease! It just seems weird because every other vehicle I have had read out at around 13.8-14.4v all the time. Is my voltage regulator in the alternator toast and the dealership missed it too?

Thanks in advance for any of your inputs.

That voltage range is about where my 2018 JLUR 3.6 and my 2014 GMC runs.

 

[SonofaSeabee]

Since doing this, I have not seen my dash voltage indicator, which I believe is more or less what the alternator is doing/has to do, go above 14.1 at any time.
What I did/do:
F42 fuse pull
Isolated Aux Battery negative cable from main battery
New H7 main battery installed
Smart Stop/Start module installed
Every night, connect the NOCO Genius 10 (may be overkill to connect every night, but I do not see a downside to this, unless someone can tell me otherwise).
Edit: The few times I see 13.8+, are very brief and voltage settles back to 12.5 - 12.8 in short time, and that high voltage only occurs when I shut down/start up Jeep several times in a row running from, say, store to store. I think connecting the NOCO every night makes up for the numerous start up/short drives I do, basically I do not drive long enough between start ups for the alternator to do its job and charge up battery enough to overcome start up juice lost.

 

[jav_eee]

I just replaced my main battery 2 weeks ago. I see the same thing. If you search, you'll see the jeep charges the jeep while coasting (that's when you see the 14 volts) and only maintains at 13 volts while driving. UNLESS it needs to be topped off in which case you'll see higher voltage while on the gas.

This is all normal operation.

 

[Obviousbicycleco]

I just replaced my main battery 2 weeks ago. I see the same thing. If you search, you'll see the jeep charges the jeep while coasting (that's when you see the 14 volts) and only maintains at 13 volts while driving. UNLESS it needs to be topped off in which case you'll see higher voltage while on the gas.

This is all normal operation.

Good info! It used to be if you revved an engine, you’d get higher readings. Things have apparently changed. Mine is doing how you described, higher voltages when coasting or letting up on throttle. Thanks for the input!

 

[Htfan]

I had done my own observations on displayed dash voltage and documented it in the thread below.

https://www.jlwranglerforums.com/fo...oltage-display-for-ess-battery-health.113355/

The voltage displayed in the dash will be all over the map due to the smart alternator and many other factors.

 

[jav_eee]

Good info! It used to be if you revved an engine, you’d get higher readings. Things have apparently changed. Mine is doing how you described, higher voltages when coasting or letting up on throttle. Thanks for the input!

yeah as someone used to the old way I’ll admit it is quite odd to see!

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