roaniecowpony
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I'm going to start a new thread on this to share what I learned. I seem to recall others also having a similar issues. I had posted my issues in other threads where other people had shared similar issues. I thought my issue was solved with a replacement (my spare) PCM. It wasn't.
Issue
The basic issue is the voltmeter, starts at a normal 14.3v ish after resetting the Intelligent Battery Sensor (IBS), then works its way down to 12.6v over several days of drive and rest cycles, after which the batteries (new) check at 12.4-12.6v (60-70%). The charging system stabilizes at the 12.6v gauge reading and stated battery state of charge.
Configuration
2018 JLUR, 3.6L, Genesis Dual Battery system, 240a alternator.
History
The Genesis Gen2 system was installed about 4 years ago. This is the system with the solenoid that draws 1 amp constantly to keep the batteries joined while sitting off. Not good for setting for more than a few days.
In late March, I installed 2 new FullThrottle 25-750 (750 CCA) batteries and fully charged them with a charger approved by FullRiver. At this time, I thought it was a good time to change out the Gen2 Genesis system with a new Gen3 system I had in my garage for the past year-ish.
During a week long road trip, my Dometic fridge quit working after about 2-3 days. I figured it was a fridge problem and continued with off-roading/traveling. On the return leg of the trip, I noticed the voltmeter was showing 12.6v. I then knew it was not the fridge, but the batteries were not getting adequate charge and the fridge battery protection had kicked in. Upon returning home, the batteries checked 12.6v or maybe it was 12.4v (hard to recall).
Eliminating Possible component issues
Of course the batteries were new and readily took a full charge, so no load test was done, although I do have a carbon pile and electronic tester.
My first thought was that the installation of the Gen3 Genesis system might have caused this. I went back over the installation instructions and verified my installation. No issues. So, I called Genesis and asked if this system has something that could cause this. Their answer was an emphatic "no, there is nothing in the (Genesis) system that could affect charging voltage".
Next, after reading about the charging system function, I suspected that the IBS was malfunctioning/failed. I replaced the IBS. Initially, it charged normally (14.x volts) After a few daily drive cycles, it was still dropping down to 12.6v on the dash gauge and the batteries reflected slightly lower state of charge.
I went back to reading about how the JL charging system works. I learned the voltage regulator is in the PCM. I had installed an unlocked PCM with altered radiator fan schedule a month or two before this charging issue. So, I installed the original PCM. Same scenario. Charging started out normal due to resetting the IBS when the batteries were disconnected. Then returned to the low voltage charging and stabilized there.
In discussions with others, I learned of similar issues others had when their alternator diodes failed. My alternator was only about 2 years old and 15k miles, but I thought I'd test that possibility. I had another good alternator in the garage (long story). So, I installed it a couple weeks ago. Same result.
I was at a loss, and started thinking about chasing the wiring for a short. After some time, I started thinking about what I had changed before this issue appeared. I kept coming back to the Genesis Gen3 installation. I still had the Gen2 Genesis and I installed it a week and change ago. I've tried to drive it daily, but I'm going through daily medical treatments that prevent it some days. Still, I've driven it about every other day or so. Most drives have been 15-20 mins, but a couple have been about an hour. It's been charging at 14.3-14v steadily. Since I thought I had solved this issue a couple times, I'm not ready to declare victory yet. But, it's looking good.
Issue
The basic issue is the voltmeter, starts at a normal 14.3v ish after resetting the Intelligent Battery Sensor (IBS), then works its way down to 12.6v over several days of drive and rest cycles, after which the batteries (new) check at 12.4-12.6v (60-70%). The charging system stabilizes at the 12.6v gauge reading and stated battery state of charge.
Configuration
2018 JLUR, 3.6L, Genesis Dual Battery system, 240a alternator.
History
The Genesis Gen2 system was installed about 4 years ago. This is the system with the solenoid that draws 1 amp constantly to keep the batteries joined while sitting off. Not good for setting for more than a few days.
In late March, I installed 2 new FullThrottle 25-750 (750 CCA) batteries and fully charged them with a charger approved by FullRiver. At this time, I thought it was a good time to change out the Gen2 Genesis system with a new Gen3 system I had in my garage for the past year-ish.
During a week long road trip, my Dometic fridge quit working after about 2-3 days. I figured it was a fridge problem and continued with off-roading/traveling. On the return leg of the trip, I noticed the voltmeter was showing 12.6v. I then knew it was not the fridge, but the batteries were not getting adequate charge and the fridge battery protection had kicked in. Upon returning home, the batteries checked 12.6v or maybe it was 12.4v (hard to recall).
Eliminating Possible component issues
Of course the batteries were new and readily took a full charge, so no load test was done, although I do have a carbon pile and electronic tester.
My first thought was that the installation of the Gen3 Genesis system might have caused this. I went back over the installation instructions and verified my installation. No issues. So, I called Genesis and asked if this system has something that could cause this. Their answer was an emphatic "no, there is nothing in the (Genesis) system that could affect charging voltage".
Next, after reading about the charging system function, I suspected that the IBS was malfunctioning/failed. I replaced the IBS. Initially, it charged normally (14.x volts) After a few daily drive cycles, it was still dropping down to 12.6v on the dash gauge and the batteries reflected slightly lower state of charge.
I went back to reading about how the JL charging system works. I learned the voltage regulator is in the PCM. I had installed an unlocked PCM with altered radiator fan schedule a month or two before this charging issue. So, I installed the original PCM. Same scenario. Charging started out normal due to resetting the IBS when the batteries were disconnected. Then returned to the low voltage charging and stabilized there.
In discussions with others, I learned of similar issues others had when their alternator diodes failed. My alternator was only about 2 years old and 15k miles, but I thought I'd test that possibility. I had another good alternator in the garage (long story). So, I installed it a couple weeks ago. Same result.
I was at a loss, and started thinking about chasing the wiring for a short. After some time, I started thinking about what I had changed before this issue appeared. I kept coming back to the Genesis Gen3 installation. I still had the Gen2 Genesis and I installed it a week and change ago. I've tried to drive it daily, but I'm going through daily medical treatments that prevent it some days. Still, I've driven it about every other day or so. Most drives have been 15-20 mins, but a couple have been about an hour. It's been charging at 14.3-14v steadily. Since I thought I had solved this issue a couple times, I'm not ready to declare victory yet. But, it's looking good.
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