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

[Raven65]

Nobody’s saying the aux can’t fail. What’s being said is that there’s an equal chance of the main failing... <snip>

I disagree that there is an equal chance of the main failing as the aux. I think the aux is far more likely to fail sooner - and there are plenty of first-hand accounts of exactly that happening on here and in many other Wrangler/Gladiator forums/groups. The aux is a dinky little thing... basically a motorcycle or lawn mower battery and the main is a MUCH larger battery - physically and capacity-wise. It is much harder to kill. I know for a fact from riding motorcycles for the past 40 years that motorcycle batteries typically don't last as long as automotive batteries (even 36-month automotive batteries) - all other things being equal. Sure, if you leave a motorcycle battery on a battery tender all the time when you're not riding (as you should), it will last a good long time, but if it sits unused very often (as most motorcycles do) and not kept on a tender they will die pretty quickly.

Can the main fail first? Sure! Defective batteries are being produced every day, but I think it's far more likely that the aux will fail first - and if you ignore the signs that it is dying (Auto stop-start not working well (or at all), aux switches not working, etc.) for very long, it will begin to kill your main and pretty soon you'll find yourself stranded - as many on here have.

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[ShadowsPapa]

Well that is what happened to mine and if people wish to say its a story then fine but there were no other factors that would have contributed to my main battery going dead other than my not running the truck for 2 days sitting in my driveway. My truck was dead and not doing much of anything. Got it to the shop and they tested both batteries. The Aux battery was dead the original main battery was fine. They replaced the aux battery, charged up the main and my main original battery is still going strong over 3 years since purchase of vehicle.

That's a different case -the aux battery didn't ruin your main battery. And it can happen that one battery can go and not have any impact on the other at all.

We're talking about how people jump and say the aux battery goes bad and ruins the other battery.
A battery can go bad and drain the other battery (that doesn't mean it WILL, just that it CAN) - and in that case it can be jumped by someone who knows what the heck they are doing. Likely if it's taken care of (unlike some people do - "i'll take care of it later") the second battery, aux or main, would be ok.
But then here's the other thing - since both batteries experience the same conditions, the same drain and fill pattern (pattern of cycling) and other factors, it's not uncommon for two batteries in parallel to go at the same time or close together. Doesn't mean one took out the other, it's the odds of failure under certain conditions.

So your case was different - one battery went and the other did not.
It's just as common for the main battery to go and not the aux battery.
Like I've said before -customers in a parts store were complaining "these days I can't get a battery to last over 4 years". My son used to own a Ford Fusion - guess what went bad in under 4 years.....

You are talking something different- and you even admitted that the aux battery did NOT ruin your main battery!
And they actually TESTED things properly = charge batteries, load test, etc. and go from there.
Too often people just say "my aux battery went and killed my main battery and ruined it".
You had one of two go bad, it happened to be the aux battery.
Could be the main battery next time.
The main battery is about as likely to go first as the aux battery.

No one tests - they all jump "See, it's like that youtube video! Waaa, the aux battery always kills the other and ruins it".

And worse "I can't jump start my Jeep" - it's likely because they are doing it wrong - connecting cables, jumping in and expecting instant results. Granted, batteries can die with a short - and that's due to abuse - they don't keep them topped off, sulfates form and slough off and short the battery. Blame the owner. Poor maintenance and patterns of use.
When a battery is dead, you have to bring it back up some first. Nobody does that.
Heck, I used to connect the cables and idle up the donor vehicle and sit back and relax for a minute before trying to start the dead vehicle. Works pretty much every time.

To prevent a battery from shorting out, draining the second battery (no matter which happens first), prevent sulfation. That happens when batteries are cycled down and left with low voltage - say, below 12.3 or so, over and over. Short drives, that sort of thing. Sulfates form and slough off inside dropping to the bottom and eventually build up and short things internally. (they are lead sulfate crystals)
To prevent that - keep the batteries topped off, use a tender that breaks up the lead sulfate crystals, etc.
AGM batteries are supposed to resist this problem better than traditional batteries, but on my 2020, I did see it kick into "desulfate" mode which sort of surprised me.

 

[ShadowsPapa]

I disagree that there is an equal chance of the main failing as the aux. I think the aux is far more likely to fail sooner - and there are plenty of first-hand accounts of exactly that happening on here and in many other Wrangler/Gladiator forums/groups. The aux is a dinky little thing... basically a motorcycle or lawn mower battery and the main is a MUCH larger battery - physically and capacity-wise. It is much harder to kill. I know for a fact from riding motorcycles for the past 40 years that motorcycle batteries typically don't last as long as automotive batteries (even 36-month automotive batteries) - all other things being equal. Sure, if you leave a motorcycle battery on a battery tender all the time when you're not riding (as you should), it will last a good long time, but if it sits unused very often (as most motorcycles do) and not kept on a tender they will die pretty quickly.

Can the main fail first? Sure! Defective batteries are being produced every day, but I think it's far more likely that the aux will fail first - and if you ignore the signs that it is dying (Auto stop-start not working well (or at all), aux switches not working, etc.) for very long, it will begin to kill your main and pretty soon you'll find yourself stranded - as many on here have.

You need to hang out in the 4xe groups and see how many complain about their batteries dying - draining and/or going bad. Percentage-wise, it's just as many as JL or JT. It's a huge complaint.
Their 4xe won't start, electronics going crazy, battery dead - and bad.

You are likely not talking AGM motorcycle batteries if you are going back that far. And yes, a traditional wet cell will suffer sulfate damage more easily and because of the dinky size, those crystals will short it sooner. Also a motorcycle charging system isn't exactly state of the art like today's vehicles so they are likely on a fixed voltage regulation system with no regard to battery temperature or condition.
Can't compare traditional wet cell motorcycle batteries to modern AGM cells.
And you yourself admitted that the motorcycle sits so the battery self-discharges. And motorcycle batteries (non-AGM) self-discharge pretty quickly, meaning they are cycled more often, cycled deeper, and never truly properly charged.
You just can't compare. Apples and oranges. You are basing it all on physical size, not patterns of use or technology involved.
BTW - the lawn mower battery in my JD is at least 7 years old now, going strong. And it's about the size of the aux battery in a Jeep.
Hmmmmm

Of course skewing the "results" people get by looking at forums and fakebook pages for proof of something is the fact that people will jump into a forum and gripe about that aux battery killing the main battery, but let the main battery go bad and few say a word! Why? Because it's pretty normal. Ho-hum, my main battery went bad.
How many go in and report a normal thing - and yet let the aux battery go bad and they will report it on as many Jeep sits as they can possible find!
So you can't use numbers from jeep sites. people like to complain about the aux battery and make sure everyone knows about it.
If the main battery goes bad in my JT - I'm not real likely to post about it - and if I did it would be just to again make sure people know to disconnect the grounds from each other, CHARGE both the new battery and the existing if it's staying in place, reset the IBS and move on. Otherwise, I'd likely replace it and move on.
I sure didn't go into the AMC pages and talk about the battery going bad in my car. And I didn't go onto the NAPA sites and complain about it.
But let that aux battery go just once, and the world will know about it.

 

[BAT]

That's a different case -the aux battery didn't ruin your main battery. And it can happen that one battery can go and not have any impact on the other at all.

We're talking about how people jump and say the aux battery goes bad and ruins the other battery.
A battery can go bad and drain the other battery (that doesn't mean it WILL, just that it CAN) - and in that case it can be jumped by someone who knows what the heck they are doing. Likely if it's taken care of (unlike some people do - "i'll take care of it later") the second battery, aux or main, would be ok.
But then here's the other thing - since both batteries experience the same conditions, the same drain and fill pattern (pattern of cycling) and other factors, it's not uncommon for two batteries in parallel to go at the same time or close together. Doesn't mean one took out the other, it's the odds of failure under certain conditions.

So your case was different - one battery went and the other did not.
It's just as common for the main battery to go and not the aux battery.
Like I've said before -customers in a parts store were complaining "these days I can't get a battery to last over 4 years". My son used to own a Ford Fusion - guess what went bad in under 4 years.....

You are talking something different- and you even admitted that the aux battery did NOT ruin your main battery!
And they actually TESTED things properly = charge batteries, load test, etc. and go from there.
Too often people just say "my aux battery went and killed my main battery and ruined it".
You had one of two go bad, it happened to be the aux battery.
Could be the main battery next time.
The main battery is about as likely to go first as the aux battery.

No one tests - they all jump "See, it's like that youtube video! Waaa, the aux battery always kills the other and ruins it".

And worse "I can't jump start my Jeep" - it's likely because they are doing it wrong - connecting cables, jumping in and expecting instant results. Granted, batteries can die with a short - and that's due to abuse - they don't keep them topped off, sulfates form and slough off and short the battery. Blame the owner. Poor maintenance and patterns of use.
When a battery is dead, you have to bring it back up some first. Nobody does that.
Heck, I used to connect the cables and idle up the donor vehicle and sit back and relax for a minute before trying to start the dead vehicle. Works pretty much every time.

To prevent a battery from shorting out, draining the second battery (no matter which happens first), prevent sulfation. That happens when batteries are cycled down and left with low voltage - say, below 12.3 or so, over and over. Short drives, that sort of thing. Sulfates form and slough off inside dropping to the bottom and eventually build up and short things internally. (they are lead sulfate crystals)
To prevent that - keep the batteries topped off, use a tender that breaks up the lead sulfate crystals, etc.
AGM batteries are supposed to resist this problem better than traditional batteries, but on my 2020, I did see it kick into "desulfate" mode which sort of surprised me.

Yea no my main battery is fine. The Aux went and brought down the main I suppose. I put the truck on a maintenance charger for about a day and got enough to be able to start the truck up. Drove it straight to the shop where they did the workup and then changed the Aux battery. Since then no issues

 

[Raven65]

You need to hang out in the 4xe groups and see how many complain about their batteries dying - draining and/or going bad. Percentage-wise, it's just as many as JL or JT. It's a huge complaint.
Their 4xe won't start, electronics going crazy, battery dead - and bad.

You are likely not talking AGM motorcycle batteries if you are going back that far. And yes, a traditional wet cell will suffer sulfate damage more easily and because of the dinky size, those crystals will short it sooner. Also a motorcycle charging system isn't exactly state of the art like today's vehicles so they are likely on a fixed voltage regulation system with no regard to battery temperature or condition.
Can't compare traditional wet cell motorcycle batteries to modern AGM cells.
And you yourself admitted that the motorcycle sits so the battery self-discharges. And motorcycle batteries (non-AGM) self-discharge pretty quickly, meaning they are cycled more often, cycled deeper, and never truly properly charged.
You just can't compare. Apples and oranges. You are basing it all on physical size, not patterns of use or technology involved.
BTW - the lawn mower battery in my JD is at least 7 years old now, going strong. And it's about the size of the aux battery in a Jeep.
Hmmmmm

Of course skewing the "results" people get by looking at forums and fakebook pages for proof of something is the fact that people will jump into a forum and gripe about that aux battery killing the main battery, but let the main battery go bad and few say a word! Why? Because it's pretty normal. Ho-hum, my main battery went bad.
How many go in and report a normal thing - and yet let the aux battery go bad and they will report it on as many Jeep sits as they can possible find!
So you can't use numbers from jeep sites. people like to complain about the aux battery and make sure everyone knows about it.
If the main battery goes bad in my JT - I'm not real likely to post about it - and if I did it would be just to again make sure people know to disconnect the grounds from each other, CHARGE both the new battery and the existing if it's staying in place, reset the IBS and move on. Otherwise, I'd likely replace it and move on.
I sure didn't go into the AMC pages and talk about the battery going bad in my car. And I didn't go onto the NAPA sites and complain about it.
But let that aux battery go just once, and the world will know about it.

While it's true that I started riding motorcycles over 40 years ago, I'm still riding them today... have four of them at the moment, so yes, I'm well acquainted with the differences between the various battery types and have used most of them at some point... from plain old-school flooded lead-acid, to AGM, to Gel, and have even tried a Li-Ion in my Suzuki DR-Z400S (and yes I'm aware there are a couple of other types beyond those, so save your breath/fingers).

Yeah, you're probably right. All these people on here and every Wrangler/Gladiator forum/group who are reporting that their aux batteries have gone bad and took their main battery with it are just mis-informed. They didn't really go bad at all... there was no problem. They weren't even stranded! Whew! What a relief that will be for them all!

Move along... nothing to see here. The dual-battery ESS system in these Jeeps is flawless. If your battery dies, it was merely defective - or was simply not charged properly due to repeated short trips... and that's somehow... our? fault?... and not Jeep's design? ?

Whatever... No need to write another novel... I'm done here.

 

[flipboltz]

Thanks. Just worried as I have a winch, a compressor, and a house battery. I know they will say some shit about other things pulling from the battery. My house battery is still at 85% so they can't say it is that but I am just worried.

Update on my Gladiator. Dealership had it for a week. Yesterday they called and said they replaced both the Aux and Main and still wasn't working because the Fuse Array was fried. The replaced the Fuse Array this morning and I picked it up and everything is working fine. All warranty work - no cost to me.

 

[Uparms]

2020 Sport, Sold at 72K miles, 8/10/2019 purchase. Both orig batteries, brakes and 60K on mopar lift and 35 x 12.5 BFG ATs. Uninvolved dealer paid me 27K for it.

 

[Schnee]

I've had my still-under-warranty '22 EcoDiesel Rubi with 31K miles in to the dealer twice for persistent ESS failure message "Auto Start/Stop Not Ready Battery Charging." The message /NEVER/ went away.

(It is more than a little annoying that this message doesn't show up as an 'error', just as a status message. So if you're not paying attention by cycling through your dash messages, you'll never see it and not realize an ESS battery has failed.)

The first time I noticed it about a month ago, the dealership replaced the Aux battery. That fixed things for about a week, then the message reappeared again, never disappearing even after extended drives. So back in the shop this morning. This time, they tell me it's the main battery that has failed, so they're replacing it.

Not a great track record for the factory-installed batteries IMHO...

I don't really want or use the auto-start/stop -- so I punch the '@Off' button on the dash as soon as I start up. But since it's still under warranty, I want all my systems working. If this happens after I'm out of my factory warranty (likely?!), I'll just self-install some bigger/better batteries.

 

[ShadowsPapa]

I've had my still-under-warranty '22 EcoDiesel Rubi with 31K miles in to the dealer twice for persistent ESS failure message "Auto Start/Stop Not Ready Battery Charging." The message /NEVER/ went away.

(It is more than a little annoying that this message doesn't show up as an 'error', just as a status message. So if you're not paying attention by cycling through your dash messages, you'll never see it and not realize an ESS battery has failed.)

Ah, the first mistake is assuming that message is because the battery failed. It isn't - it simply means the battery SoC is low. Doesn't mean bad at all.
Heck, I used to see that quite a bit because my 2020 sat a lot and got a lot of drives under 30-40 minutes when I did drive it. So the batteries never got a full charge and week after week, they got lower and lower.
I finally charged each battery independently, reset the IBS, put it back together and drove it for months - until I traded it in, with no more "battery charging" messages.
The main and aux batteries were both fine.
It's not an ERROR! It simply means low battery, and it's charging.

The first time I noticed it about a month ago, the dealership replaced the Aux battery. That fixed things for about a week, then the message reappeared again, never disappearing even after extended drives. So back in the shop this morning. This time, they tell me it's the main battery that has failed, so they're replacing it.

And that makes sense - the message COULD have been related to the main/crank battery - because when you are driving they are connected together. So it's seeing the combined capacity of both, not just the aux.

Your contention that the message is somehow related to an aux battery being bad is mistaken.
Could be the main battery.
And it doesn't mean either are "bad" - just that they are in a state of discharge - the State of Charge is too low for ESS and it won't function if the MAIN battery is too low.
My gut says your "battery charging" message was more main battery.

Too much faulty information, bad/incorrect assumptions and so on out there related to batteries and charging systems.

 

[Rocksalt]

couldn't vote because I pre emptively did the jumperless aux battery bypass and simply replaced my main battery at 3 years.

 

[Schnee]

Too much faulty information, bad/incorrect assumptions and so on out there related to batteries and charging systems.

In my case the conclusion is simpler than your hand waving:
Both batteries went "bad" (wouldn't hold a full charge) within earshot of each other.

The facts for my almost-2-year-old JT:

1. Extended driving/trips over multiple weeks => The ESS never kicked in and the "Auto-Start/Stop Not Ready Battery Charging" message ruled the day.
2. Dealer tested aux battery and said it was bad => replaced it.
3. Extended driving/trips over multiple weeks => The ESS never kicked in and the "Auto-Start/Stop Not Ready Battery Charging" message ruled the day.
4. Dealer tested the main battery and said it was bad => replaced it.

 

[ShadowsPapa]

In my case the conclusion is simpler than your hand waving:
Both batteries went "bad" (wouldn't hold a full charge) within earshot of each other.

The facts for my almost-2-year-old JT:

1. Extended driving/trips over multiple weeks => The ESS never kicked in and the "Auto-Start/Stop Not Ready Battery Charging" message ruled the day.
2. Dealer tested aux battery and said it was bad => replaced it.
3. Extended driving/trips over multiple weeks => The ESS never kicked in and the "Auto-Start/Stop Not Ready Battery Charging" message ruled the day.
4. Dealer tested the main battery and said it was bad => replaced it.

Some detail left out - they tested the aux battery, said it was bad and replaced it.
But did they automatically conclude "oh, it's got to be the aux battery" and concentrate on it and never bother testing the main battery??
Could be it was also in bad shape and would have failed a test on the same day.
You'll never know unless you have a printout of the tests they run.
Was it just assumed it was the aux - and that's where they went?

Been at this too long to trust most dealers with electric stuff - even a little bit. I've probably got decades more experience than any one of them, maybe than any 2 or 3 of them in a typical shop as far as electrical.
So I still wonder - did they assume? Was a test even done at that time and if so, do you have the test results?

 

[bluemoon110]

My batteries were factory-installed in May 2022. I think my Aux. battery must be dead. The auto stop-start quit working some months back, I don't remember exactly when. I do a lot of around-town low-speed trips, and I didn't notice exactly when it quit functioning.

Also, can I connect a trickle charge without disconnecting the battery and not screwup the electronics?

 

[ShadowsPapa]

My batteries were factory-installed in May 2022. I think my Aux. battery must be dead. The auto stop-start quit working some months back, I don't remember exactly when. I do a lot of around-town low-speed trips, and I didn't notice exactly when it quit functioning.

Also, can I connect a trickle charge without disconnecting the battery and not screwup the electronics?

ESS not working can be many things, including low voltage of the battery pair.
However........... it sounds like you are a good candidate for a charger while the Jeep sits.
No, you won't hurt a thing, and you do not have to disconnect anything.
I charge mine through the 7 pin trailer connector using either my CTEK charger or a BatteryMINDER 1500 depending on how much my JT has been sitting, that sort of thing.

If you have a volt meter, you can use a meter on the battery posts and see what the voltage is with the Jeep NOT running - that will give at least some indication on where things are............

Good news - you can charge things together, and it won't hurt a thing at all.
Always charge through the IBS - intelligent battery sensor, and not directly to the battery post. Or, connect to a ground at the chassis or use the trailer plug connections.
Many of us have shown how we do that in other threads and will be happy to help if needed.

 

[WestwallNF104A]

I am now 2 years and a month on my original batteries.

However, I installed a 345 watt solar system, with a Battleborn batteries 270ah LiFePO battery that maintains my original battery system. So far so good.

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