Auxilary Battery Died then Main Battery Died - Important Info

[chorky]

I just had a thought. Have you done a resistance check on the maxi fuse going to the aux battery? To make sure its not bad?

Since the two batteries are in parallel at all times, in order for the aux battery to be 11 volts, the main battery also must be 11 volts. The only time one can be more than the other is if they are not connected in parallel, and saw the main is 12.5 and the aux is 11 - connect them together and the current flows from the main to the aux until they are equalized.
But with these, they are connected in parallel, all the time it's sitting in your garage.
Putting jumper cables on the main is a direct line to the starter and the voltage will equalize save for the voltage drop in the wires themselves. Since the main is the cranking battery, and it's pos goes right to the starter..........

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[jeepers29]

You can often jump start the dual battery jeep the old fashioned way and I've done it several times. My wife's WK2 had the same exact setup. The AUX battery went bad. I jumped started her Jeep from my Jeep, no issues at all - with a bad aux battery. I had my truck running the whole time, left the cables on for a couple of minutes before we cranked her Jeep and it took right off.

The dealer said her aux battery had gone bad and was draining the main or crank battery every time I charged things. It got to the point that charging did no good - take the charger off and the voltage was barely 11 volts.

You can also charge both without doing any more than taking the IBS off the negative terminal of the main battery IF the N3 fuse is good. No need to take a ton of things off and apart. Just separate things at the negative terminal on the crank battery.

Connect one charger to the positive cables on the main battery and the other to the cable you lift off the main battery negative terminal - that'll charge the aux battery if the fuses are all good.
Then the other charger connects to the negative post of the main battery and the positive cables at the main battery.
I charged both batteries at the same time using two chargers by only taking the IBS with the negative cables off the main battery neg terminal.

If the N3 fuse is blown, you can't charge the aux battery like I've outlined...........

Please explain what IBS is. Thanks for this tidbit, by the way.

 

[WhyNotJeep]

My ESS is fine now but it doesn't like the AC on.

 

[abe57]

My ESS is fine now but it doesn't like the AC on.

My understanding is when the ESS kicks on it shuts down the AC ...

 

[Joe Gladiator]

The primary purpose of the ESS battery is to keep the computers stable so they don't reboot from low voltage while the truck is running. It also makes startup faster as it keeps the computers on all the time and you don't have to wait for them to boot each time the truck is turned on. The ESS system cannot be disabled or eliminated, it is always active and monitoring. The available mods and hacks just keep it from turning the engine off.

too bad, but makes sense.

 

[abe57]

Genesis Dual Battery Kit has been available for a long time.
https://www.genesisoffroad.com/jt-dual-battery-kit

Wow! They must be growing trees!??

I may go this route to eliminate that rink-a-dink smaller battery

 

[ShadowsPapa]

My understanding is when the ESS kicks on it shuts down the AC ...

No, it does not. Only the compressor. AC can be on and it will continue to cool until it can't, then if the cabin temp rises, the engine restarts.
Everything like heat, radio, lights, and AC work when ESS shuts the engine down. And the AC fan will run until there's no more heat being exchanged then as the cabin temp rises above a certain number of degrees above your set temperature it will restart the engine. Same for heat- as long as the cabin stays within so many degrees of your setting, the engine stays off. It will restart if the cabin temp goes outside specific areas based on your chosen temperature setting.
It will also restart after a pre-set given amount of time or if the voltage drops too low.
Mine was working great today...........

 

[ShadowsPapa]

Please explain what IBS is. Thanks for this tidbit, by the way.

Intelligent Battery Sensor. These are made by Bosch.

The Intelligent Battery Sensor (IBS) contains a low value resistor, or shunt. The shunt creates voltage drop, which is read by an internal microcontroller to determine the current flow in and out of the battery. In addition to the shunt, the IBS contains a sensor to monitor the battery's temperature. Data gathered by the IBS, including temperature, voltage, and current measurements, are transmitted over a LIN communication bus to either the Body Control
Module (BCM) or the Powertrain Control Module (PCM), depending on the application. The IBS serves two primary purposes. The first is to provide the Powertrain Control Module (or PCM) with both immediate and historical battery information, so the PCM can precisely control the charging system. Precise charging is important on a vehicle equipped with an Absorbent Glass Material (or AGM) battery, because they are especially sensitive to overcharging.
The second purpose is to provide data to the BCM for operation of the load-shedding feature. A fused power circuit and the LIN bus are connected to the IBS though a two-terminal connector.
In addition to real-time measurements, the IBS transmits some calculated battery data over the LIN bus, including state of charge, state of health, and state of function. These values are calculated by storing measurements over time.
The battery sensor is readable/diagnosable via a "scan tool" that can display all of the available parameters needed for vehicle servicing or trouble shooting.

 

[jeepers29]

Intelligent Battery Sensor. These are made by Bosch.

The Intelligent Battery Sensor (IBS) contains a low value resistor, or shunt. The shunt creates voltage drop, which is read by an internal microcontroller to determine the current flow in and out of the battery. In addition to the shunt, the IBS contains a sensor to monitor the battery's temperature. Data gathered by the IBS, including temperature, voltage, and current measurements, are transmitted over a LIN communication bus to either the Body Control
Module (BCM) or the Powertrain Control Module (PCM), depending on the application. The IBS serves two primary purposes. The first is to provide the Powertrain Control Module (or PCM) with both immediate and historical battery information, so the PCM can precisely control the charging system. Precise charging is important on a vehicle equipped with an Absorbent Glass Material (or AGM) battery, because they are especially sensitive to overcharging.
The second purpose is to provide data to the BCM for operation of the load-shedding feature. A fused power circuit and the LIN bus are connected to the IBS though a two-terminal connector.
In addition to real-time measurements, the IBS transmits some calculated battery data over the LIN bus, including state of charge, state of health, and state of function. These values are calculated by storing measurements over time.
The battery sensor is readable/diagnosable via a "scan tool" that can display all of the available parameters needed for vehicle servicing or trouble shooting.

thank you for taking the time to learn me something new.

 

[Deadeye]

Your dealership gave you some bad information. Back in '20, I had a lot of issues with my batteries. It most certainly can be jumped by just using the main terminals. The biggest issue is when the aux goes bad, it typically starts a parasitic draining cycle on the main battery hides the issue for a while. It also prematurely kills the main. You need to swap both at the same time, regardless of how the main tests. It'll most likely die too soon. And of course the aux batteries in particular have poor quality out of a plant in mexico.

 

[Deadeye]

If you have to jump start - the ESS should be disabled by the system anyway. Even if my batteries are low, but will still start the vehicle, ESS won't work. Get below 12.4 BATTERY volts and it's disabled.
We went though a lot of this with my wife's WK2 a couple of years back - ESS not working was the first clue the aux battery wasn't very good.

Like I have posted in a thread I started on my truck's battery voltages, the ESS not working is the first clue that you have a problem. Those who have disabled it permanently via tazer or whatever won't have that warning that there's a problem.
ESS not working is what told my wife there was a problem with her Jeep. She complained "why isn't it stopping at lights anymore" - and 2 weeks later, if the Jeep sat for a couple of days it had to be jump started. Simple process - connect cables as you would with any other vehicle, wait a couple of minutes, then start it. Too many connect and instantly try to start the dead vehicle. You should run the running vehicle at a high idle after connecting, and the dead vehicle should start.

ESS not working is a clue you may have a problem - a battery problem. It's a symptom of other things.

You clearly understand the system and are providing some good info to people. However, there are definitely issues with the ESS detecting defective aux batteries in certain circumstances. Some of my first posts on this forum involved a STARS case regarding my batteries. After several battery changes and some diagnostics from the corporate engineers, the primary issue were some bad aux batteries out of Mexico. Some way, some how, it didn't completely disable the ESS until the main was to a certain drainage level. The conclusion from the engineers was that the extra toll on the main was wearing prematurely, made worse by a second bad aux. Then a good aux wore out early because the main went bad and started draining the aux. Finally, they swapped out both at the same time and its been two years almost without an issue.

 

[ShadowsPapa]

You clearly understand the system and are providing some good info to people. However, there are definitely issues with the ESS detecting defective aux batteries in certain circumstances. Some of my first posts on this forum involved a STARS case regarding my batteries. After several battery changes and some diagnostics from the corporate engineers, the primary issue were some bad aux batteries out of Mexico. Some way, some how, it didn't completely disable the ESS until the main was to a certain drainage level. The conclusion from the engineers was that the extra toll on the main was wearing prematurely, made worse by a second bad aux. Then a good aux wore out early because the main went bad and started draining the aux. Finally, they swapped out both at the same time and its been two years almost without an issue.

Replace both at the same time....... yes. And most sites or experts agree, that unbalanced battery sizes and capacities is not a good thing.

Agreed on the detection as well. The IBS is on the main battery........ the charging and discharging from that battery are all that is detected by the IBS. It can't "see" or sense the aux battery. If the aux is causing a drain, it doesn't know what the drain is, only that there's a drain.

When I used a charger on my wife's WK2 (multiple times) with a very bad aux battery, it started right up and she drove fine and the main held enough power for a few hours for her to start it and get back home.
Finally it reached a point where I wasn't able to charge things for it to start and after charging 12 hours, and disconnecting, the voltage dropped fast to sub 11 volts.
So after charging all night it didn't have enough to activate anything, no click, no nothing.
Jump starting worked - glad it didn't die driving it to the dealership but even with a totally trashed aux battery, it started when jump starting it.

 

[Deadeye]

Replace both at the same time....... yes. And most sites or experts agree, that unbalanced battery sizes and capacities is not a good thing.

Agreed on the detection as well. The IBS is on the main battery........ the charging and discharging from that battery are all that is detected by the IBS. It can't "see" or sense the aux battery. If the aux is causing a drain, it doesn't know what the drain is, only that there's a drain.

When I used a charger on my wife's WK2 (multiple times) with a very bad aux battery, it started right up and she drove fine and the main held enough power for a few hours for her to start it and get back home.
Finally it reached a point where I wasn't able to charge things for it to start and after charging 12 hours, and disconnecting, the voltage dropped fast to sub 11 volts.
So after charging all night it didn't have enough to activate anything, no click, no nothing.
Jump starting worked - glad it didn't die driving it to the dealership but even with a totally trashed aux battery, it started when jump starting it.

Very similar for me, and particularly with the main, it didn’t initially test bad on several iterations, even though it was at a point that it was impairing normal operations.

classic case of legislation “pushing” things along before they are fully marketable. I don’t have a problem with green ideology as a whole. But the EV systems tech are just simply not in a state to be getting implemented whole scale like it is, not to mention infrastructure. And then there is the manufacturing issues with such systems. It’s likely that they more than offset any gains in emissions gains in emissions. But hey, we can charge the consumer more and at the same time pretend that consumer emissions are even a fraction of the wonton commercial emissions.

 

[WhyNotJeep]

When the battery of either one fails, replace them both. Is there a prefered brand? Odyssey is a high quality and a little more $$$. Worth it?? At least we don't have a E-torque battery yet.

 

[ShadowsPapa]

When the battery of either one fails, replace them both. Is there a prefered brand? Odyssey is a high quality and a little more $$$. Worth it?? At least we don't have a E-torque battery yet.

Just my .0009483 cents worth -
When mine die, if it's out of warranty, I'm going NAPA for both. I've had fantastic luck and I've done research into where they are made (USA) and read a few reviews. I have NAPA batteries in both of my current cars and had a NAPA battery in my Silverado when that battery finally died at about 6 years (the original factory Motorcraft battery in my F250 went 12 years)

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