Aux. Battery: When did yours die (or how old is it now if it hasn't)?

[Mr._Bill]

Question - if you always turn auto start stop off, will the aux still drain the main battery? I don’t understand deleting the aux if you can just press a button. Unless, the aux battery is causing other issues that will affect the main. I don’t want to run into issues on the side of the road with the battery even if I turn ESS off. I know this is a broken record, but if someone could explain, that would be appreciated.

The two batteries are paralleled together all the time, essentially acting as one bigger battery. They are only separated for two situations. The first is during the startup test of the AUX battery. The computer checks to see if there is a battery connected there, and what the voltage reading is. If no battery there, or the voltage is too low, ESS is automatically prevented from activating until the next startup. The second is during actual ESS events. The AUX battery is used to keep the computers and electronics on and stable, and the Main battery is used for re-starting the engine and a few other high-draw items.

The ESS system is always active and monitoring everything. It cannot be turned off or disabled. It can only be prevented from turning the engine off when ESS conditions call for it. Letting ESS operate, or pressing the dash button to turn it off, has no effect on the charging of the batteries.

When two batteries are paralleled together, the failure of one has the potential to drain the other. It depends on the type of failure. The batteries try to stay equalized, and one will pull from the other to keep the voltage level up. When one battery fails to a point it cannot be charged anymore, it causes a problem. A small drain can be covered up for a while by the daily driving that keeps the other battery charged. This is when the console messages on the screen of ESS or AUX Switches Unavailable let you know that there is a battery problem that needs looked at. A large drain can leave you stranded after being parked for a while, but there are usually always signs of a problem before you get to that point.

Sponsored

 

[High Alextude]

The two batteries are paralleled together all the time, essentially acting as one bigger battery. They are only separated for two situations. The first is during the startup test of the AUX battery. The computer checks to see if there is a battery connected there, and what the voltage reading is. If no battery there, or the voltage is too low, ESS is automatically prevented from activating until the next startup. The second is during actual ESS events. The AUX battery is used to keep the computers and electronics on and stable, and the Main battery is used for re-starting the engine and a few other high-draw items.

The ESS system is always active and monitoring everything. It cannot be turned off or disabled. It can only be prevented from turning the engine off when ESS conditions call for it. Letting ESS operate, or pressing the dash button to turn it off, has no effect on the charging of the batteries.

When two batteries are paralleled together, the failure of one has the potential to drain the other. It depends on the type of failure. The batteries try to stay equalized, and one will pull from the other to keep the voltage level up. When one battery fails to a point it cannot be charged anymore, it causes a problem. A small drain can be covered up for a while by the daily driving that keeps the other battery charged. This is when the console messages on the screen of ESS or AUX Switches Unavailable let you know that there is a battery problem that needs looked at. A large drain can leave you stranded after being parked for a while, but there are usually always signs of a problem before you get to that point.

This is a fantastic explanation, thank you. I’ll leave the batteries as is until there are any signs as you’ve mentioned, then I’ll consider possibly doing a delete.

 

[ShadowsPapa]

This is a fantastic explanation, thank you. I’ll leave the batteries as is until there are any signs as you’ve mentioned, then I’ll consider possibly doing a delete.

If you don't drive your jeep very often or if it's only for short drives when you do - consider a battery tender. Charge the batteries with a good AGM charger, then keep them up with a tender.
I've noticed after my son put over 700 miles on mine in less than a week - the thing was running very difference voltages on the dash and the batteries actually measured 12.75 volts after shutting off for a while. Then a couple of days later driving it saw the voltage display on the dash stay in the 13s and even lower at times. It makes a huge difference.
The problem is that these have enough parasitic drain when parked they just don't get fully charged driving them infrequently or short drives.
That shortens their lives.
I know the 12v battery in my wife's 4xe is going to die an early death if I don't start charging it now and then as sometimes it sits for a week at a time, so I'm going to start keeping it charged up for her. It gets driven so infrequently and on short drives so it's already in FORM mode - I told her she'd got to take it out and drive it more - and drive it long and up to some speed. City driving is horrible for the batteries - highway drives are best.

 

[High Alextude]

If you don't drive your jeep very often or if it's only for short drives when you do - consider a battery tender. Charge the batteries with a good AGM charger, then keep them up with a tender.
I've noticed after my son put over 700 miles on mine in less than a week - the thing was running very difference voltages on the dash and the batteries actually measured 12.75 volts after shutting off for a while. Then a couple of days later driving it saw the voltage display on the dash stay in the 13s and even lower at times. It makes a huge difference.
The problem is that these have enough parasitic drain when parked they just don't get fully charged driving them infrequently or short drives.
That shortens their lives.
I know the 12v battery in my wife's 4xe is going to die an early death if I don't start charging it now and then as sometimes it sits for a week at a time, so I'm going to start keeping it charged up for her. It gets driven so infrequently and on short drives so it's already in FORM mode - I told her she'd got to take it out and drive it more - and drive it long and up to some speed. City driving is horrible for the batteries - highway drives are best.

Which is kinda crazy, right? You would think the start stop would be specifically for city driving but it sounds like it only damages/worsens it.

 

[Mr._Bill]

Which is kinda crazy, right? You would think the start stop would be specifically for city driving but it sounds like it only damages/worsens it.

The ESS is intended to save gas in city driving situations, but those are the worst for keeping the batteries charged. Due primarily to the draw of all the electronics, it needs at least 30 minutes of steady driving daily to keep the batteries charged. As mentioned, a battery maintainer is a great idea for extending battery life if it is not driven daily.

 

[ShadowsPapa]

It is weird. It was solely running on battery power while in park. Soon as it was shifted in D it worked normally. I think its possible my air compressor was drawing too much power even with the engine at 2000rpm.

There are some JT owners I wish were a bit closer as there are some of those vehicles I'd love to pull into my shop and do some serious digging on just what's going on - measure draw, and a whole list of other things. (well, and get to actually know some of the people too, LOL)

I find it odd that an air compressor - 12 volts, would draw so much, more than a winch, more than a snow plow hydraulic pump. Something's going on and it's just impossible to know without a lot of fact-finding.

I also wish I was about 30 years younger - I'd get back into school and be back into the thick of things like this.
Oh, well - maybe there's reincarnation - or is that when you come back as a flower? Maybe it's reincarceration?

 

[Lunentucker]

There are some JT owners I wish were a bit closer as there are some of those vehicles I'd love to pull into my shop and do some serious digging on just what's going on - measure draw, and a whole list of other things. (well, and get to actually know some of the people too, LOL)

I find it odd that an air compressor - 12 volts, would draw so much, more than a winch, more than a snow plow hydraulic pump. Something's going on and it's just impossible to know without a lot of fact-finding.

I also wish I was about 30 years younger - I'd get back into school and be back into the thick of things like this.
Oh, well - maybe there's reincarnation - or is that when you come back as a flower? Maybe it's reincarceration?

I wish Jeep was half as interested as you are.

 

[JW Jeep]

If you don't drive your jeep very often or if it's only for short drives when you do - consider a battery tender. Charge the batteries with a good AGM charger, then keep them up with a tender.
I've noticed after my son put over 700 miles on mine in less than a week - the thing was running very difference voltages on the dash and the batteries actually measured 12.75 volts after shutting off for a while. Then a couple of days later driving it saw the voltage display on the dash stay in the 13s and even lower at times. It makes a huge difference.
The problem is that these have enough parasitic drain when parked they just don't get fully charged driving them infrequently or short drives.
That shortens their lives.
I know the 12v battery in my wife's 4xe is going to die an early death if I don't start charging it now and then as sometimes it sits for a week at a time, so I'm going to start keeping it charged up for her. It gets driven so infrequently and on short drives so it's already in FORM mode - I told her she'd got to take it out and drive it more - and drive it long and up to some speed. City driving is horrible for the batteries - highway drives are best.

Yes mine did the same on last trip. I have been keeping an eye on it and try to get out for a decent drive every day but being retired now and I got the motorcycle and the Wife’s suv. So Next few weeks before fall I am going to do the battery tender and probably go through rear tow plug ? It’s garaged but hate leaving hood up all the time ?

 

[Mr._Bill]

Yes mine did the same on last trip. I have been keeping an eye on it and try to get out for a decent drive every day but being retired now and I got the motorcycle and the Wife’s suv. So Next few weeks before fall I am going to do the battery tender and probably go through rear tow plug ? It’s garaged but hate leaving hood up all the time ?

Some of the battery maintainers come with a two pin harness that can be run out through the grille, so that the hood doesn't have to be lifted to connect it. You just have to remember to disconnect it before driving away. ?

 

[JW Jeep]

Some of the battery maintainers come with a two pin harness that can be run out through the grille, so that the hood doesn't have to be lifted to connect it. You just have to remember to disconnect it before driving away. ?

Ya I have that on my motorcycle like that. 2 pin harness. I was just worried about dealership crap ? With tow plug they will never know ? I’m probably over thinking this again?
thank you for the reply.

 

[KevinM60]

Yes mine did the same on last trip. I have been keeping an eye on it and try to get out for a decent drive every day but being retired now and I got the motorcycle and the Wife’s suv. So Next few weeks before fall I am going to do the battery tender and probably go through rear tow plug ? It’s garaged but hate leaving hood up all the time ?

I have my battery tender chord running up through the passenger side front wheel well with the tender itself sitting on the front bumper so I don't have to leave the hood up.
I just started using mine this week and have the clamps to make sure it works right but I'll install the 2-pin harness this weekend and tuck it beside the battery when not in use.

 

[kabookie10]

Mine just died a couple weekends ago. Left me stranded. However, it was the main battery that died. The aux battery was low charge and for over a year the auto start stop message gave me "unavailable battery charging". Since it was under warranty I showed it to the dealer and they supposedly looked at it and said it was fine and probably just low and needed to charge. WRONG.. I don't know what happened but it drove fine and without warning I got in it after making a quick stop and no crank. The aux battery had enough juice to turn on lights and make the whole electrical system go haywire but the main battery was shot. I ended up replacing both batteries.

 

[ecidiego]

At 2 years now no battery issues. Start/Stop always works. Truck sits minimum of 2 and sometimes 7 days at a time, even has a flashing strobe/ultrasonic pest deterrent on the main battery full time under the hood. Half the drives I do take are 3 miles or less. Lucky?

 

[56cbr600rr]

Mine lasted about 3k miles, around 3 months.. That being said, I know for sure my Glad was onthe lot for about 8 months before I bought it... Could have something to do with in..

 

[Jeeperjamie]

My main went out at 54,000 my aux battery is still going strong at 75,000 miles

Sponsored