Voltmeter wanderings

[Lugwrench]

I got a message from Mopar that my charging system was acting up and I should see my dealer. I'm away from home, so I just starting monitoring my voltmeter--something few owners are likely to do. Here is what I am seeing: down long hills, or in general when you have engine braking, the voltage is high--14.6 or 14.7. Other times the voltage is lower, and particularly when under load climbing, it drops to 12.6-13.0. No load on the level, it is somewhere in the 13 volt range.

I don't understand why the voltage decreases under load and peaks under engine braking. If anyone else has ever monitored their voltmeter (and I can imagine no has!), have you seen performance like this? Can you explain it? Do I have a problem?

Sponsored

 

[WranglerMan]

I got a message from Mopar that my charging system was acting up and I should see my dealer. I'm away from home, so I just starting monitoring my voltmeter--something few owners are likely to do. Here is what I am seeing: down long hills, or in general when you have engine braking, the voltage is high--14.6 or 14.7. Other times the voltage is lower, and particularly when under load climbing, it drops to 12.6-13.0. No load on the level, it is somewhere in the 13 volt range.

I don't understand why the voltage decreases under load and peaks under engine braking. If anyone else has ever monitored their voltmeter (and I can imagine no has!), have you seen performance like this? Can you explain it? Do I have a problem?

The JL uses smart charging so when driving at a normal steady speed or idled the voltage with be steady but when braking or decelerating the voltage will climb then once stopped or back to a normal steady speed it will drop again

 

[NCJL]

Yes the JL (I think most modern vehicles) has a smart charging system. I installed a redarc battery charger in my off-road trailer. I monitored the voltmeter after install. The voltages were similar to yours.

 

[OldGuyNewJeep]

If anyone else has ever monitored their voltmeter (and I can imagine no has!), have you seen performance like this?

Search the forum for battery or for IBS. Yes, many of us monitor the health of our batteries and charging system.

What you are seeing is normal, by the way.

If I were you I’d put a tender on your batteries and reset the IBS (search forum for howto) before bothering with a dealer visit.

 

[four low]

That " message from Mopar " means that that you have " over the air Surveillance of the operating parameters of your JL ?
That's a LOT of Data being Hoovered up, think about it.
Will you also get a message from Mopar if speed, braking, driver attention, anything exceeds "normal" limits ??

 

[JimLee]

That " message from Mopar " means that that you have " over the air Surveillance of the operating parameters of your JL ?
That's a LOT of Data being Hoovered up, think about it.
Will you also get a message from Mopar if speed, braking, driver attention, anything exceeds "normal" limits ??

Sport, no connection to the outside world, perfect.

 

[OldGuyNewJeep]

That " message from Mopar " means that that you have " over the air Surveillance of the operating parameters of your JL ?
That's a LOT of Data being Hoovered up, think about it.
Will you also get a message from Mopar if speed, braking, driver attention, anything exceeds "normal" limits ??

Do you carry a smart phone? If so, this should be the least of your worries…

Unless you’re a homesteader living off the grid, you’re every movement is tracked and recorded. Sad, but true.

It must suck to be a serial killer these days…

 

[WranglerMan]

Here is a short clip I did awhile back and this is how the voltages run on a electrically healthy JL ( battery wise ) is supposed to be

 

[Lugwrench]

Well, thank you all! I certainly feel better with the multiple assurances that things are probably okay. I have a four-hour drive later this week to return to home base, and I don't want problems en route.

However...I was planning a 100 mile outing today, but turned back after the first few miles. I saw lower voltages with periods in the 12 volt range down to 12.1 at the lowest. I think anything below 13 is a state of discharge, so I decided not to take the trip.

I'll have to drive to get home, so will just hope for the best then. Meanwhile I'll check the state of charge each night with my smart charger. Last night it reported 87% (12.7V), although I'm not sure how much to trust the calculation.

Wranglerman: Thanks so much for the video.

Oldguynewjeep: I did look up IBS reset and will so so.

Internet surveillance: I agree with all comments on this. I hate the surveillance, but I don't feel like I can fight it very effectively. I understand that if I get a Tazer, it will block the surveillance. That has both positive an negative aspects.

 

[WranglerMan]

@Lugwrench 12.66 is what most in the industry considered fully charged but AGM batteries are considered fully charged slightly higher at 12.9ish but the JL’s charging system will not put it that high unless you change the parameters using a programmer like JSCAN.

If you put your Jeep on a charger like a NOCO 10 or similar and wait until fully charged you will see 12.9-13.2 but once the surface charge drops off you should be in the 12.8 range but it may be a tad higher with no connected load.

12.1 to me is unacceptable even if it’s been parked for several days but if you are relying on the EVIC display for that voltage that’s truly not very accurate as to get to the voltage display you have to be in ACC or run mode without the engine running and by then the JL is pulling power for other things so it’s best to get your readings directly off the batteries with a meter.

It has been discussed in great detail that these batteries on the JL need attention in regard to charging so it’s best to invest in a good quality smart charger of adequate size to properly maintain the batteries and the batteries they are putting in these Jeep are not the best but I would start with a good solid charge first and see if all settles down.

 

[Lugwrench]

Again, thanks for all your replies. Will "Wranglerman" seems to know a lot about electrical systems and he gave particularly detailed info.

I took the Jeep out for an all-day trek into the desert today. I was hesitant, but, just in case, I bought one of those battery jump starters (plenty large enough for a diesel) and I had friend Jeeps along. At the end of the day, my battery still measured 13.0 volts and my smart charger declined to charge it further.

As implied by you all, reading the tea leaves of your in-dash voltmeter is difficult.

 

[WranglerMan]

Again, thanks for all your replies. Will "Wranglerman" seems to know a lot about electrical systems and he gave particularly detailed info.

I took the Jeep out for an all-day trek into the desert today. I was hesitant, but, just in case, I bought one of those battery jump starters (plenty large enough for a diesel) and I had friend Jeeps along. At the end of the day, my battery still measured 13.0 volts and my smart charger declined to charge it further.

As implied by you all, reading the tea leaves of your in-dash voltmeter is difficult.

13.0 volts on the EVIC is perfectly acceptable and your alternator is so to speak throwing a trickle charge to your batteries.

I have a dual Genesis system and after doing a deep recondition charge the EVIC display indicates 12.7 and metered directly at the batteries connected I get 13.0 but after taking off the charger the surface charge drops off and it’s usually 12.8-12.9 so the alternator is doing little to nothing on output but if I let it sit parked for 12-15 hrs the EVIC display is usually in the mid 13’s and after driving all day it’s low 13’s like 13.1-13.2 and then by mid week it usually shows low 13’s

If you choose to to keep batteries at peak you could disconnect the IBS from the main crank battery and this will force the alternator to throw 14+ volts to the batteries all the time.

I don’t necessarily agree on the smart charging logic a lot of makers decide on but it’s supposed to increase battery life and reduce the load on the system by minimizing drag put on by the alternator and increase mpg but it’s a Jeep and mpg was never a concern for me or I would have got a Prius.

There are ppl here on the Forum that are so much more knowledgable on these systems but when I changed my battery system I became somewhat consumed on how the charging system needed to be maintained I scoured blogs and manual looking for info.

 

[Lugwrench]

I have now driven the 4-hour return trip to my home. At the conclusion of the trip, I got another message from Jeep that my charging system was in distress. The previous message had been generated near the end of the same drive in the opposite direction.

Today the dealer examined the car and could find no problem. Called Jeep to see what was going on, but nothing was discovered I guess. Tightened connections, compared charging to other Jeeps. They told me to ignore the messages and come back if I get a check-engine light.

For my own measurement, I see the engine-off battery voltage is 12.9 volts instead of the 13.0 I had seen during my vacation.

Next week I'm leaving on a 1000 mile road trip, so I'll take my jump starter and battery charger. And some crossed fingers.

 

[WranglerMan]

@Lugwrench you need to get a meter ( digital preferred ) to check voltage directly at the battery and check both batteries separately also invest in a quality charger and fully charge the batteries.

Also by having a meter you will be able to see what charge is being thrown to the batteries while its idled and running, you said the Dealer said no issues but did they do a load test on the batteries ?

 

[Lugwrench]

@Lugwrench you need to get a meter ( digital preferred ) to check voltage directly at the battery and check both batteries separately also invest in a quality charger and fully charge the batteries.

Also by having a meter you will be able to see what charge is being thrown to the batteries while its idled and running, you said the Dealer said no issues but did they do a load test on the batteries ?

No problem. The motor-off voltages I’ve given were taken with a Fluke meter. My charger is a fairly new one from Griot’s Garage. Overpriced, but works well. When I use it to fully charge, resulting battery says 13.0 volts. I haven’t measured the voltage with the motor running because the EVIC meter suggests it varies all the time, but I’ll give it a shot.

The dealer report says they checked and tightened connectors at the battery and alternator. They said they compared the charging voltage with another Jeep and the voltage was the same. There are obviously questions that could be asked, but you don’t get to talk to the mechanic

The dealer report does not mention a load test. Maybe the battery itself is faulty. I have seen even new batteries misbehave, but it is rare.

Sponsored