Alternator or battery?

[Brahmajoe]

When i turn my car to the run position it reads 12.2 volts on the dash. When i start the jeep it jumps to 14. While driving it stays around 12.6. Is this an issue? I have a low vibration at idle and im unsure if the alternator is shot or maybe something to do with charging the battery. Help. Thanks

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[sharpsicle]

Nope. Normal. These are smart alternators and only provide the voltage needed at the time. If it doesn't need to recharge, it won't be at 14v, and that's okay.

 

[Brahmajoe]

Nope. Normal. These are smart alternators and only provide the voltage needed at the time. If it doesn't need to recharge, it won't be at 14v, and that's okay.

Thanks. The 12.2 v is low though isnt it? I thought it should be atound 12.6 i resd that 12.2 is 50% charged

 

[Commodus]

Thanks. The 12.2 v is low though isnt it? I thought it should be atound 12.6 i resd that 12.2 is 50% charged

12.2 is not too low with engine off. There are continuous draws when in run position and ambient temperature either hot or on the cold side

 

[Mr._Bill]

When i turn my car to the run position it reads 12.2 volts on the dash. When i start the jeep it jumps to 14. While driving it stays around 12.6. Is this an issue? I have a low vibration at idle and im unsure if the alternator is shot or maybe something to do with charging the battery. Help. Thanks

Disconnect the ground cables and separately charge each battery with a AGM charger. Let it sit for a while and then check the voltage with a meter. Fully charged, with no load, a good AGM battery should read 12.8 volts. Completely disconnect the IBS from the negative terminal of the Main battery and let is sit about ten minutes. Put it all back together and see if it behaves any better.

If either battery reads 12.5 volts or less with a full charge, it will soon be due for a replacement. The average life expectancy of batteries in the JT is three years. If the batteries are not kept charged, they lose capacity and die even sooner. The parasitic draw is fairly high, especially with the cellular equipped head unit. They need to be driven regularly or have a battery maintainer attached.

 

[Brahmajoe]

Disconnect the ground cables and separately charge each battery with a AGM charger. Let it sit for a while and then check the voltage with a meter. Fully charged, with no load, a good AGM battery should read 12.8 volts. Completely disconnect the IBS from the negative terminal of the Main battery and let is sit about ten minutes. Put it all back together and see if it behaves any better.

If either battery reads 12.5 volts or less with a full charge, it will soon be due for a replacement. The average life expectancy of batteries in the JT is three years. If the batteries are not kept charged, they lose capacity and die even sooner. The parasitic draw is fairly high, especially with the cellular equipped head unit. They need to be driven regularly or have a battery maintainer attached.

So the 12.2 with the key on engine off is no good

 

[Mr._Bill]

So the 12.2 with the key on engine off is no good

It doesn't exactly mean the battery is bad, but it is not a good sign. That is near the level where things like Remote Start quit working. Even at 11.9 volts, it will still start the engine, but the system is not happy with it. Charge the batteries, reset the IBS, and see if they recover any. You may be able to extend the useful life a bit.

 

[ShadowsPapa]

When i turn my car to the run position it reads 12.2 volts on the dash. When i start the jeep it jumps to 14. While driving it stays around 12.6. Is this an issue? I have a low vibration at idle and im unsure if the alternator is shot or maybe something to do with charging the battery. Help. Thanks

Your voltage should be much higher than 12.6 if your battery is actually 12.2.
Best bet is to get a volt meter - even a $20 from Walmart - will do - and measure the battery voltage with the fob clear away from the Jeep. Open hood with engine off and measure the actual voltage. If it's 12.2, then it's way low and you should not be seeing voltage below 13.0 until the batteries are recharged a bit - until they recover.
Normal charged battery, fully charged AGM is 12.8 (roughly)
I can park my JT in the garage at 8pm and go out and measure the battery voltage with my Fluke meter at 11am the next day and it will be around 12.66 volts. That's because of the parasitic drain of being parked overnight plus there's a load on it while I'm measuring the voltage because they are connected to live systems even with the truck off. If I disconnected the batteries, I'd probably read 12.7 or better.
Mine has to sit at least 2 to 3 days to get down to 12.4 volts.

Something is way off here if you have an actual reading of 12.2 volts.

I would charge the batteries with a good AGM charger, fully disconnect the IBS (intelligent battery sensor - it's clamped to the main battery negative post). You need to disconnect the LIN network connector - the small 2 wire connector from the IBS.
Take the IBS off, charge the batteries, and with the IBS off and disconnected, it has been reset.
If after charging the batteries with a good AGM charger, they don't come up to at least 12.7 volts, you have battery issues.

That alternator should not drop down to 12.6 volts with very low batteries unless the IBS senses the battery is HOT.

So the 12.2 with the key on engine off is no good

It means the batteries are not being fully charged - either it's not driven enough, long enough, frequently enough, or they aren't taking and holding a charge.............. but with the running voltage being seen at only 12.6 volts on very low batteries, something is definitely going on.

12.2 is not too low with engine off. There are continuous draws when in run position and ambient temperature either hot or on the cold side

It shouldn't be that low - not for good battery life. That's really low. Mine has never been that low and it sometimes sits for 2 or 3 days.
If I get in mine now and just hit the big button to put it in acc or run mode and not start it, it will definitely read higher than 12.2 volts. Mine doesn't drop that far even during an ESS stop unless it sits 2 minutes stopped.

 

[Brahmajoe]

Your voltage should be much higher than 12.6 if your battery is actually 12.2.
Best bet is to get a volt meter - even a $20 from Walmart - will do - and measure the battery voltage with the fob clear away from the Jeep. Open hood with engine off and measure the actual voltage. If it's 12.2, then it's way low and you should not be seeing voltage below 13.0 until the batteries are recharged a bit - until they recover.
Normal charged battery, fully charged AGM is 12.8 (roughly)
I can park my JT in the garage at 8pm and go out and measure the battery voltage with my Fluke meter at 11am the next day and it will be around 12.66 volts. That's because of the parasitic drain of being parked overnight plus there's a load on it while I'm measuring the voltage because they are connected to live systems even with the truck off. If I disconnected the batteries, I'd probably read 12.7 or better.
Mine has to sit at least 2 to 3 days to get down to 12.4 volts.

Something is way off here if you have an actual reading of 12.2 volts.

I would charge the batteries with a good AGM charger, fully disconnect the IBS (intelligent battery sensor - it's clamped to the main battery negative post). You need to disconnect the LIN network connector - the small 2 wire connector from the IBS.
Take the IBS off, charge the batteries, and with the IBS off and disconnected, it has been reset.
If after charging the batteries with a good AGM charger, they don't come up to at least 12.7 volts, you have battery issues.

That alternator should not drop down to 12.6 volts with very low batteries unless the IBS senses the battery is HOT.



It means the batteries are not being fully charged - either it's not driven enough, long enough, frequently enough, or they aren't taking and holding a charge.............. but with the running voltage being seen at only 12.6 volts on very low batteries, something is definitely going on.


It shouldn't be that low - not for good battery life. That's really low. Mine has never been that low and it sometimes sits for 2 or 3 days.
If I get in mine now and just hit the big button to put it in acc or run mode and not start it, it will definitely read higher than 12.2 volts. Mine doesn't drop that far even during an ESS stop unless it sits 2 minutes stopped.

Thanks for the info, I know I shouldn’t really compare the two but my wife has a 21 wrangler and out of curiosity I checked her cruising voltage and it was around 13.6 about a volt higher then mine. It will at times shoot up to 13 ish sometimes 14 when I’m driving but yesterday when I checked it cruising speeds where usually below 13 with little spikes here and there

 

[Brahmajoe]

Thanks for the info, I know I shouldn’t really compare the two but my wife has a 21 wrangler and out of curiosity I checked her cruising voltage and it was around 13.6 about a volt higher then mine. Mine will at times shoot up to 13 ish sometimes 14 when I’m driving but yesterday when I checked it cruising speeds where usually below 13 with little spikes here and there

 

[Brahmajoe]

Your voltage should be much higher than 12.6 if your battery is actually 12.2.
Best bet is to get a volt meter - even a $20 from Walmart - will do - and measure the battery voltage with the fob clear away from the Jeep. Open hood with engine off and measure the actual voltage. If it's 12.2, then it's way low and you should not be seeing voltage below 13.0 until the batteries are recharged a bit - until they recover.
Normal charged battery, fully charged AGM is 12.8 (roughly)
I can park my JT in the garage at 8pm and go out and measure the battery voltage with my Fluke meter at 11am the next day and it will be around 12.66 volts. That's because of the parasitic drain of being parked overnight plus there's a load on it while I'm measuring the voltage because they are connected to live systems even with the truck off. If I disconnected the batteries, I'd probably read 12.7 or better.
Mine has to sit at least 2 to 3 days to get down to 12.4 volts.

Something is way off here if you have an actual reading of 12.2 volts.

I would charge the batteries with a good AGM charger, fully disconnect the IBS (intelligent battery sensor - it's clamped to the main battery negative post). You need to disconnect the LIN network connector - the small 2 wire connector from the IBS.
Take the IBS off, charge the batteries, and with the IBS off and disconnected, it has been reset.
If after charging the batteries with a good AGM charger, they don't come up to at least 12.7 volts, you have battery issues.

That alternator should not drop down to 12.6 volts with very low batteries unless the IBS senses the battery is HOT.



It means the batteries are not being fully charged - either it's not driven enough, long enough, frequently enough, or they aren't taking and holding a charge.............. but with the running voltage being seen at only 12.6 volts on very low batteries, something is definitely going on.


It shouldn't be that low - not for good battery life. That's really low. Mine has never been that low and it sometimes sits for 2 or 3 days.
If I get in mine now and just hit the big button to put it in acc or run mode and not start it, it will definitely read higher than 12.2 volts. Mine doesn't drop that far even during an ESS stop unless it sits 2 minutes stopped.

Just figured I’d give more info, today Jeep in run it said 12.2 again then on my half hour commute to work it was at 14.7 the entire time, once stop start kicked in at a light you would see the voltage drop to 12.4. I know I have to run your test to be sure, but does it seem like the alternator is working but battery not holding the charge or charging slow

 

[ShadowsPapa]

Just figured I’d give more info, today Jeep in run it said 12.2 again then on my half hour commute to work it was at 14.7 the entire time, once stop start kicked in at a light you would see the voltage drop to 12.4. I know I have to run your test to be sure, but does it seem like the alternator is working but battery not holding the charge or charging slow

It would appear - without further checking/testing, that the commute isn't enough to get the batteries fully charged.
14.7 indicates it sees the batteries are quite low, 12.4 isn't horrible for a drop during ESS stop.
I would definitely get a full charge into the batteries and go from there, but so far, it looks like it's simply a case of not enough driving to get the batteries fully charged. Even with a charger and my batteries only sitting at about 12.4 or so, it takes at least a couple of hours to get them fully charged. I've seen as long as almost all day if low enough.
14.7 is very normal while driving if it senses the batteries are very low - and 12.2 is very low.

 

[Brahmajoe]

It would appear - without further checking/testing, that the commute isn't enough to get the batteries fully charged.
14.7 indicates it sees the batteries are quite low, 12.4 isn't horrible for a drop during ESS stop.
I would definitely get a full charge into the batteries and go from there, but so far, it looks like it's simply a case of not enough driving to get the batteries fully charged. Even with a charger and my batteries only sitting at about 12.4 or so, it takes at least a couple of hours to get them fully charged. I've seen as long as almost all day if low enough.
14.7 is very normal while driving if it senses the batteries are very low - and 12.2 is very low.

Sorry one more question lol, is the 12.2 reading the main battery or both somehow

 

[ShadowsPapa]

Sorry one more question lol, is the 12.2 reading the main battery or both somehow

Because when the truck is shut off, sitting in your driveway or garage, both batteries are connected together in parallel, it's sort of an average of both.
That's why when there are things that pop up like this, I suggest taking the ground cables off the IBS that's on the main battery, removing the IBS, taking the two ground cables apart, and charging the main battery by itself, and the aux battery by itself (clipping the charger to the positive cable on the main battery and the ground cable that goes down to the aux battery)
This way you can tell if one is weak or not taking a charge. It's possible both are good but just low, or it could be either the main or the aux battery is going weak, lowering the voltage of the pair when everything is connected.

 

[Hunter#1]

I posted on this also. This weekend I traveled for 2 hrs to the beach , the lowest the gauge read was 14.2. when I got there , the next morning I drove for 45 min, gauge read 1
14,5, Stopped for coffee, restarted and gauge read 14 .1 . The next day 2 hr drive home and gauge went between 14.5 and home at 14.1. This morning , started at 14. 7 then down to 14.4. Are these readings showing that the batteries are weak. Other than that , I have no problems with the Glad at all, no elec or running problems. I would just hate to be on the beach and it will go dead . This would be a tremendous tow bill. Lol

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