Voltage in a Wrangler

epriev

epriev

Active Member
I don't know why I noticed the voltage while on the weekend off-roading trip.

It hovered between 13.0 to 13.2. It didnt seem to increase with higher RPM. This seemed low based on previous vehicles that hovered closer to 14 and move more with RPM.

In the morning, the voltage would go to the mid to high 14s for a few minutes when off throttle. On throttle, back to low 13s. After the morning, it wouldn't go above 13.2.

Normal, or potential issue? About 5k miles and 4 months on a 2025 JLU.
 
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epriev said:
I don't know why I noticed the voltage while on the weekend off-roading trip.

It hovered between 13.0 to 13.2. It didnt seem to increase with higher RPM. This seemed low based on previous vehicles that hovered closer to 14 and move more with RPM.

In the morning, the voltage would go to the mid to high 14s for a few minutes when off throttle. On throttle, back to low 13s. After the morning, it wouldn't go above 13.2.

Normal, or potential issue? About 5k miles and 4 months on a 2025 JLU.
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Sounds like a normal jeep to me.
 
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This means your battery is charged and does require a charging voltage or current at that moment, The alternator puts out enough juice to keep everything running and your batteries topped off. You will notice if you leave it shut off for a couple of days or only make very short trips, the voltage will go into the 14.2-14.3 range and will likely stay there for a while. That is your charging voltage.

I work away from home and my drive from my room to the dock is less than one mile. Over 7 days, that 2 mile round trip never has a chance to recharge my batteries; so the whole next week I am basically playing catch up and occasionally put it on a trickle charger at home.
 
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4LO_Send_It said:
This means your battery is charged and does require a charging voltage or current at that moment, The alternator puts out enough juice to keep everything running and your batteries topped off. You will notice if you leave it shut off for a couple of days or only make very short trips, the voltage will go into the 14.2-14.3 range and will likely stay there for a while. That is your charging voltage.

I work away from home and my drive from my room to the dock is less than one mile. Over 7 days, that 2 mile round trip never has a chance to recharge my batteries; so the whole next week I am basically playing catch up and occasionally put it on a trickle charger at home.
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Welcome.
 
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4LO_Send_It said:
This means your battery is charged and does require a charging voltage or current at that moment, The alternator puts out enough juice to keep everything running and your batteries topped off. You will notice if you leave it shut off for a couple of days or only make very short trips, the voltage will go into the 14.2-14.3 range and will likely stay there for a while. That is your charging voltage.

I work away from home and my drive from my room to the dock is less than one mile. Over 7 days, that 2 mile round trip never has a chance to recharge my batteries; so the whole next week I am basically playing catch up and occasionally put it on a trickle charger at home.
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That makes sense in these more computer driven cars.

I have been a bit paranoid on alternator issues since having to leave my Xterra on the trail 4 times in a 2 month period and field replacing the alternator. The OEM failed on a very muddy trail with multiple deep water crossings. Nissan, Bosch x2 and a Napa brand, all failed within 2 weeks. I could change these with my eyes closed by the last one. Put on a Mean Green and it lasted 14 years and then a Rugged Rocks high output. The 2nd Naoa brand that I replaced with the Mean Green stayed in the gear bag, until a friend had his fail on the trail.

We rotated batteries to get me to a safe spot. Each time after normal business hours and several hours from home.

But back the reason for the original question, I was worried because I was use to watching the voltage in the months after the replacements and quick failures and the voltages hovered around 14.5 and fluctuated +/- 0.3V before plummeting to under 12 when they died. So when I saw 13.0 Volts, my 1st thought was failing alternator, as it was under a similar situation as my 1st failed alternator on the xterra, muddy & water crossings. Google didnt help either as it said it should be 14 +/- 0.5.
 
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epriev said:
That makes sense in these more computer driven cars.

I have been a bit paranoid on alternator issues since having to leave my Xterra on the trail 4 times in a 2 month period and field replacing the alternator. The OEM failed on a very muddy trail with multiple deep water crossings. Nissan, Bosch x2 and a Napa brand, all failed within 2 weeks. I could change these with my eyes closed by the last one. Put on a Mean Green and it lasted 14 years and then a Rugged Rocks high output. The 2nd Naoa brand that I replaced with the Mean Green stayed in the gear bag, until a friend had his fail on the trail.

We rotated batteries to get me to a safe spot. Each time after normal business hours and several hours from home.

But back the reason for the original question, I was worried because I was use to watching the voltage in the months after the replacements and quick failures and the voltages hovered around 14.5 and fluctuated +/- 0.3V before plummeting to under 12 when they died. So when I saw 13.0 Volts, my 1st thought was failing alternator, as it was under a similar situation as my 1st failed alternator on the xterra, muddy & water crossings. Google didnt help either as it said it should be 14 +/- 0.5.
Click to expand...
AGM batteries require this strange charging cycle. Different than traditional batteries. It is likely that different vehicles handle it differently (e.g using some memory and software controlled, or based entirely on initial battery voltage and charging current).

Sorry to hear about all the alternator problems.
 
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