Low running voltage

[Maydaygray]

I recently noticed that my Wrangler JLU Rubicon (2018 model) dash display indicated that the voltage with the engine running was around 12.4-12.6. Normally I would think this would be around 14+ volts, especially at highway speeds. I have a newish (1.5 years old) Optima yellow top and same age 2nd battery. I went to Autozone since that is where I purchased the Optima and had them use their diagnostic machine. Two tests showed a good starter and battery but bad voltage regulator. They said it was the alternator. I purchased and installed a new 240 amp model and the readings are exactly the same! On a side note, I use this as a second vehicle and always pop the hood when done driving it so that I can attach a Battery Tender 4amp model charger. Even if I just got back from driving in the woods all day, the battery indicator light still takes at least 1-2 hours to turn full green.

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[Windshieldfarmer]

Something is wrong with your charging system…assuming the readings are correct. If the battery is fully charged I would expect 13.5 v …up to 14.2 v if the battery is low. Probably will take a dealer diagnosis. Don’t run it like this too long…very hard on the battery.

 

[mwilk012]

Autozone is literally incapable of diagnosing any problem. Their job is to sell parts.

There is probably nothing wrong with your Jeep.

You would know if it wasn't charging.

 

[Jim1964]

New vehicles don’t charge at constant voltage and haven’t for years. Probably nothing was wrong, unfortunately all you did was spend money. If you replaced the OEM alternator with aftermarket that’s a downgrade.

Vehicle charging is controlled by the computer now, which monitors voltage and amperage at the battery and decides when to charge and how much. In the cause of better fuel economy.

 

[Maydaygray]

Holy smokes! Well, I have a 240 amp now. At least if the ratings are to be believed. I will say it looks absolutely brand new.

 

[Fatboy97]

My Jeep operates the same way ever since the main battery was replaced. Original battery in Jeep showed in the 13v + range all the time when driving. I don’t drive it much and it always sits on a trickle charger when not in use. The main battery was replaced because it would not go above 60% charge and the charging wires got super hot. I sometimes think that 12.6v might be wrong but everything is working perfect. I don’t know much about all this new technology with smart charging and all but I think you are fine. I load test both batteries from time to time. I will be deleting the secondary battery when it needs to be replaced.

 

[Maydaygray]

This seems to be the general consensus. I'd ask my local Jeep service dept but they are helpless.

 

[Maverick909]

the New Smart Alt. is what you are see. Unless the computer shows the battery needs charging. on longer trips my wrangler will stay in the 12.6V range. Something you can do is run your lights and A/C on max and it should kick the Alt. on

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