Start stop not ready / battery charging message after aux battery change - What next?

[Jeeperjamie]

For anyone following along, I ended up replacing the main battery on my own and after driving for about 5 miles the Start Stop system started working again.

That's what I did with mine as well. I'm 18,000 miles in since I replace mine and everything is still working great. I think we jump to conclusions a lot before knowing the real reason why some things are going on. I immediately thought it was my aux battery as well. Glad you got it worked out.

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[xman1564]

My new to me 21 JTRD always has this message on. Today I replaced the Aux battery and still see the message even after a short test drive. During the drive I did notice the voltage fluctuating between 12 and 14 volts. Once I got home I used my volt meter to test the original aux battery since it was now out of the Jeep and it was reading about 12.3 volts. I also tested the main battery with the engine off and it was also reading 12.3 volts. Unfortunately I did not test the new aux battery before installing it but it had a date code of 12/22 so I'm sure it was fine.

What other options do I have to resolve this issue?

12.3 is too low should be 12.5-12.8 re charge, let it set for 30 min and re test should be 12.5 or higher

 

[xman1564]

That's what I did with mine as well. I'm 18,000 miles in since I replace mine and everything is still working great. I think we jump to conclusions a lot before knowing the real reason why some things are going on. I immediately thought it was my aux battery as well. Glad you got it worked out.

18 k mi should be under factory warrantee if its 3 yrs or under

 

[xman1564]

100% correct. The guy I deal with at my dealership told me the same thing. It cost me $86 for them to test it right but they knocked it off the price of the main battery they installed. Worthy it for peace of mind as far as I'm concerned.

true! if you suspect your battery charge them individually on a slow charge for a couple hrs then re test on a manual load tester use it in conjunction with a volt meter volts should be up 12.5 or higher, load battery and see how low volts go, it at 10 vlts or lower replace bat if not down to 10 vlts and voltage dosent bounce back to 12.5 or higher bad battery bat residual should bounce back to 12.5 or higher on any good battery if it dosent then replace 35 yr mechanic

 

[xman1564]

true! if you suspect your battery charge them individually on a slow charge for a couple hrs then re test on a manual load tester use it in conjunction with a volt meter volts should be up 12.5 or higher, load battery and see how low volts go, it at 10 vlts or lower replace bat if not down to 10 vlts and voltage dosent bounce back to 12.5 or higher bad battery bat residual should bounce back to 12.5 or higher on any good battery if it dosent then replace 35 yr mechanic

but only after re charge

 

[ShadowsPapa]

12.3 is too low should be 12.5-12.8 re charge, let it set for 30 min and re test should be 12.5 or higher

If the batteries were full, during a drive, the diesel can read as low as 12.2-12.3 volts.
That's how it's programmed. But if the batteries aren't low - or hot - it should read higher when running.
An AGM battery needs to be 12.7-12.8 to be fully charged.

After a drive, shutting off engine, a battery reading lower than roughly 12.6 (because of the electronics, the parasitic drain) isn't fully charged.

But then I'm wondering why a dead thread with the issues resolved, finished/fixed, is resurrected again?

 

[sharpsicle]

Gotta increase that post count somehow!

 

[ShadowsPapa]

Gotta increase that post count somehow!

Man, 3 and 4 posts, quoting self, and searching out all of the old resolved threads with confusing and not quite great advice.......

 

[Jeeperjamie]

18 k mi should be under factory warrantee if its 3 yrs or under

18K since it's been replaced, it had 54,000 miles on it when the Main went bad.

 

[ShadowsPapa]

Here we go! All of the old battery and aux threads searched and brought back to life, starting all over again, and frankly, not real impressed with some of the info that's left out but very important.....
This one 5 months old and long since properly resolved.

 

[ShadowsPapa]

35 yr mechanic

52 years here.
Own shop, and................

Sorry, just had to!! HA

(but these days I wonder - what if I HAD accepted that service manager spot at the Jeep dealership? I'll never know. Instead, I started up my old business again.)

 

[xman1564]

18K since it's been replaced, it had 54,000 miles on it when the Main went bad.

that sucks

 

[ShadowsPapa]

Why does that suck? He's getting good time/miles out of his batteries.

 

[htremper]

Mine was always at 14 volts and the ESS never worked. Apparently this is the charging voltage so it must have logic to disable ESS when this is happening.

This is exactly what mine shows...I assume that is the charging but not the actual charge from of the battery itself. So can I assume I need a new battery? (I mean its a 2020 72k on the ordinal battery)

 

[ShadowsPapa]

Mine was always at 14 volts and the ESS never worked. Apparently this is the charging voltage so it must have logic to disable ESS when this is happening.

No, that logic isn't logic and is making connections that just don't belong.

This is exactly what mine shows...I assume that is the charging but not the actual charge from of the battery itself. So can I assume I need a new battery? (I mean its a 2020 72k on the ordinal battery)

Not sure what you mean by that at all.
The voltage displayed on the cluster is "system voltage".
If the engine is not running and the alternator not charging, then system voltage is battery voltage.
If the engine is running and the alternator is charging any at all, then it's the voltage of the system being supplied by the alternator.
The only time you can see the voltage of the battery itself is when the engine is off, and you press the button without touching the brake to put it in run mode without starting.
However, then you have battery voltage minus the load of the electronics that are now "on" drawing from the battery. So if you do that and see 12.2 for example, if it was turned off it would likely actually be higher.
The only way to get a check of the battery voltage itself is by opening the hood and using a volt meter on the battery terminals - nothing on, nothing running, not in ACC mode, not in RUN mode.
Even then it's going to reflect a tiny drop due to the constant load of the electronics if the truck's systems aren't "sleeping".

Just because you see 14 volts doesn't mean squat. Not unless you can associate that with other readings you have seen and establish a pattern. With short drives, that may be all you'll see depending on the ambient temperature and if the batteries aren't 100% state of charge (SoC)

So - you need to have both batteries tested to see where they are at health-wise, or, just go ahead and replace them (them being plural)
If you fully charge each independently and then have each independently load tested and one passes but the other does not, then you have the option of replacing only the one that doesn't pass.
A parts store can't test these without disconnecting things!
Don't drive your Jeep to Advance Auto, O'Reilly's, AutoZone, PepBoys or whatever and have them test - unless you get a person who knows how to do it correctly by disconnecting the batteries, separating them, and testing each battery on its own - making sure that first they are at least 60% or more charged.
Most of these places simply clamp on a cheap device, not caring if the battery is fully charged or not, and testing without realizing there are two different batteries of different sizes in many vehicles, including ours.

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