Andy29847
Well-Known Member
- First Name
- Andy
- Joined
- Oct 25, 2020
- Threads
- 14
- Messages
- 552
- Reaction score
- 934
- Location
- South Carolina
- Vehicle(s)
- 2020 Wrangler Rubicon, 2020 Gladiator Rubicon
- Occupation
- Retired
- Thread starter
- #1
I am the lucky owner of 2 2020 Jeeps. One is a JT, one is a JLU. I had some start/stop trouble with the JLU. It took 3 visits to the dealer before they fixed it by installing a new main battery. Everything has worked since then. I was a little concerned about having on old battery paired with a new battery. My concern had me watching the dash voltmeter every time I drove the Jeep. I noticed that on the Jeep with the new main battery, the voltmeter always showed 14.7. The other truck, the one with 2 older batteries, would start around 14.7 and work it's way down to 14.2. I think I understand why the Jeeps were behaving like this. The Jeep battery program and sensors were reading the battery situation and responding to the condition of the batteries. For the JT, I'm guessing that charging voltage was slightly high (after 30-45 minute drive) because of the age of the batteries. Anyway, all this heavy thought has led to a battery plan for my vehicles. Before laying out the plan, let me write that I am not a heavy thinker. I am a heavy reader. There are several guys here that with more knowledge, experience, and training than I have, and some of them have been studying the Jeep JL/JT battery/charging system since the models first came on the market. Thanks to youse guys here before me for sharing your work and knowledge.
The Plan
If your Jeep is still in the original 36month/36,000 mile warranty, your batteries are covered by that warranty. If you have a problem, let the dealer fix it.
Once you are out of warranty, at the first sign of battery problems (constant max charge on voltmeter, stop/start not working, etc.) abandon the aux battery and focus on the main battery. I abandoned the aux battery on my JLU by removing the negative battery lead from the main battery post and pulling the F42 fuse. The end of the negative lead needs to be insulated and secured. Once I did this on my JLU (the Jeep with the new main battery), I noticed that on a drive, my charging voltage would begin at 14.7, but would work its way down to 13.9.
FWIW, the Jeep systems work the same with one battery or 2 batteries. Not having a aux battery is not important to me because I normally turn the stop/start off the first time I think about it (usually at the first stop
). I'm guessing that if you are using one battery, and the voltage gets too low for the stop/start, the Jeep will disable that feature and give you a warning in the message center.
The new main battery the dealer put in my JLU is a mid-grade Group 94/H7 battery. If I have to buy a new battery for one of my Jeeps, I will buy a premium grade battery. A premium grade Group 94/H7 will have 800 or more cold cranking amps.
My belief is that I have eliminated some of the complexity of the battery system without giving anything away. My hope is that my battery and charging system will now behave like the vehicles I have owned for the past 50 years. I do not want to have to run to the dealer for battery problems.
The Plan
If your Jeep is still in the original 36month/36,000 mile warranty, your batteries are covered by that warranty. If you have a problem, let the dealer fix it.
Once you are out of warranty, at the first sign of battery problems (constant max charge on voltmeter, stop/start not working, etc.) abandon the aux battery and focus on the main battery. I abandoned the aux battery on my JLU by removing the negative battery lead from the main battery post and pulling the F42 fuse. The end of the negative lead needs to be insulated and secured. Once I did this on my JLU (the Jeep with the new main battery), I noticed that on a drive, my charging voltage would begin at 14.7, but would work its way down to 13.9.
FWIW, the Jeep systems work the same with one battery or 2 batteries. Not having a aux battery is not important to me because I normally turn the stop/start off the first time I think about it (usually at the first stop
). I'm guessing that if you are using one battery, and the voltage gets too low for the stop/start, the Jeep will disable that feature and give you a warning in the message center. The new main battery the dealer put in my JLU is a mid-grade Group 94/H7 battery. If I have to buy a new battery for one of my Jeeps, I will buy a premium grade battery. A premium grade Group 94/H7 will have 800 or more cold cranking amps.
My belief is that I have eliminated some of the complexity of the battery system without giving anything away. My hope is that my battery and charging system will now behave like the vehicles I have owned for the past 50 years. I do not want to have to run to the dealer for battery problems.
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