Not charging....what to check OTHER than alternator?

[Darel]

Currently sitting in a hotel room 3 hours from home because my '21 JT stopped charging yesterday. Had it towed to a dealer.

I already know that they are going to deny my warranty and possibly refuse to work on it because I have a Genesis Gen3 dual battery system. I also know that's not the problem but anyway....

Planning ahead because I already have two other dead cars in the house and I don't want to just fire the parts cannon. What ELSE other than the alternator should I check? I've been working on cars for 30+ years and have worked on stuff way older than me, but I've actually never had an alternator go bad on me. So before I just drop $300 on one I want to check everything.

With a meter I am not getting any output off the main post of the alternator. Just reading battery voltage. So what might be telling the alternator not to charge? If anything? I know it's not just cut and dry with these new smart charging systems.

Thanks!

Sponsored

 

[whysoserious]

https://www.jeepgladiatorforum.com/...arging-system-on-a-2022-jt.97827/post-1566484

 

[Lost1wing]

Ibs sensor? You did not forget to look at it? I'm not familiar with your system or how it connects. I would think you would still need the ibs.

The alternator is controlled by the ecu via inputs from the ibs. Alternator output is fused at the fuse array, then on to the battery.

May just a bad ibs.

 

[Darel]

Ok so there's really nothing between the PCM and the alternator. So basically if I am getting no output (battery voltage only) at the post on the alternator, the alternator is bad. Or else the entire PCM is bad. Am I correct in this thinking?

 

[Badunit]

From the '23 service manual.

 

[whysoserious]

DTC and troubleshooting stuff. Page 1031 starts with low battery voltage...

 

[Darel]

Did some reading on the IBS and if that went bad it would constantly be putting out 14v.

 

[Lost1wing]

Ok so there's really nothing between the PCM and the alternator. So basically if I am getting no output (battery voltage only) at the post on the alternator, the alternator is bad. Or else the entire PCM is bad. Am I correct in this thinking?

The IBS gives the pcm the charge state of the battery. If the pcm does not see that info from the IBS, it will not command an output from the alternator.

I just watched the Genisis dual batt gen3 video. Seems to me like you have an installation error or the emergency switch was not in auto. If left on, both batteries will drain. You still would have your current charging system problem. But if the switch was in auto, you should have been able to turn it on to start the engine.

 

[Lost1wing]

Did some reading on the IBS and if that went bad it would constantly be putting out 14v.

You would have an error code (cel) I think.

 

[Darel]

I haven't touched the Genesis system or settings since I installed it two years ago, and it was working and set up properly while I was having the issue. So the IBS can fail and create a no-charge state?

 

[ShadowsPapa]

You would have an error code (cel) I think.

Yes, if the IBS is bad, there's codes for that.

Of course there are various ways things can go bad.

Interesting to note that when people talk of issues with their batteries or charging AND they have some 3rd party setup with DC/DC charging and other batteries, no one ever shows how things are connected.......... did they connect properly above the IBS or to the chassis ground, or directly to the negative battery terminal, for example? A lot of unknowns.

I'd also wonder - what were the signs that it stopped charging?
These can run down to 12.7 and be perfectly normal IF the IBS decides the batteries are fully charged and/or the temperature is high.
Are the batteries involved AGM batteries?
What voltage is being measured? Just saying "battery voltage" doesn't tell us much.

There's a high current fuse between the alternator and the batteries (300 amps) - but I'd expect the alternator output to go high if that is blown.
So what's the voltage at the batteries, what's the voltage at the alternator output post.

Is this all setup properly, using the IBS and all loads taken either from the top of the IBS or a chassis ground for the ground point? (making sure no load is grounded directly to the battery post under the IBS)

I also suspect a dealer won't touch this, especially for any warranty work - it's no longer a Jeep system.
If it came to my shop, I'd charge extra - two reasons - it's a non-typical setup, and, it was installed by owner so there's a huge "human factor" involved in trying to troubleshoot.

 

[Lost1wing]

I would have rechecked your fender ground and all 4 posts connections. Yes your IBS could be giving erroneous info to the ecu. There is also the possibility that your Alternator was putting out constant 14+ volts (ibs issue still) and now your batteries prematurely died as a result.

Curious as to why you went to the Genisis system in the first place. Do you have electronics or other high demand users installed? If so, could that be a reason the batteries are dead? The switch could have been on without you knowing, but it should have been in auto.

 

[Lost1wing]

Yes, if the IBS is bad, there's codes for that.

Of course there are various ways things can go bad.

Interesting to note that when people talk of issues with their batteries or charging AND they have some 3rd party setup with DC/DC charging and other batteries, no one ever shows how things are connected.......... did they connect properly above the IBS or to the chassis ground, or directly to the negative battery terminal, for example? A lot of unknowns.

I'd also wonder - what were the signs that it stopped charging?
These can run down to 12.7 and be perfectly normal IF the IBS decides the batteries are fully charged and/or the temperature is high.
Are the batteries involved AGM batteries?
What voltage is being measured? Just saying "battery voltage" doesn't tell us much.

There's a high current fuse between the alternator and the batteries (300 amps) - but I'd expect the alternator output to go high if that is blown.
So what's the voltage at the batteries, what's the voltage at the alternator output post.

Is this all setup properly, using the IBS and all loads taken either from the top of the IBS or a chassis ground for the ground point? (making sure no load is grounded directly to the battery post under the IBS)

I also suspect a dealer won't touch this, especially for any warranty work - it's no longer a Jeep system.
If it came to my shop, I'd charge extra - two reasons - it's a non-typical setup, and, it was installed by owner so there's a huge "human factor" involved in trying to troubleshoot.

I just watched the installation and description video on the Genisis web site and I would recommend the OP do so too. That way he can look for a potential error if one was made.

 

[Darel]

Batteries are AGM. Started truck after work, as soon as I pulled out of the parking lot the battery light came on. Battery voltage was 11.9v. Shut if off and started it back up again, same thing. Battery light comes on after 2-3 minutes, voltage 11.9 and after another 2-3 minutes I get the A and service start/stop. I have a 3-hour drive home so I figured screw it, maybe the two batteries will last, maybe not. Shut off the radio and HVAC and headlights and hit the road, but the battery voltage just kept dropping, within about 5 miles it got below 10v and I started getting system shutdown messages (ABS, power saving mode, etc.). I pulled into a parking lot, lucky I had my meter in the truck, checking the main post of the alternator to both of the negative battery posts and a chassis ground I would get exactly whatever the battery voltage was. Which I kind of expected. But if I was getting 14+v out of the alternator and the batteries were still discharging that would have been something like that main 300a fuse or something. But since I don't have alternator output, I have to assume either the alternator is bad or something is telling it to not charge.

The system itself is pretty simple, take out old batteries and tray, drop in new tray and batteries, and the isolator system drops right on top of the batteries. Theres no changing any of the factory wiring where the battery posts are. There was one wire that went to the mini aux battery that got taped off and left unconnected, don't recall now what it was because it's been two years

And to that point, the system has been installed and working fine for two years. This is a failure of a factory component, just have to figure out what when they sent my warranty. And I did call genesis tech support while waiting for the tow truck and they confirmed there's no failure mode in their equipment that could result in a no-charging condition.

I didn't have my obd reader in the truck with me though so I couldn't check for codes. I did NOT have a CEL oddly, just it battery light and then the individual system failure lights when the batteries ran down too low.

Thanks guys!

 

[Darel]

And by the way this is NOT a dead battery condition. This is a not-charging-the-fully-charged-batteries condition. In fact I have not run the batteries down that far, I've started and driven the truck a few times just to move it. Batteries are good and I don't have a weird drain or anything. Installed the Genesis because 1. Didn't feel like dealing with the common aux battery issues and 2. I have a winch, a couple deer lights, and an air compressor, although the winch and compressor don't even get hooked up to the system until I am actually using them. They're not connected to the batteries.

Sponsored