My thoughts on the auxiliary battery

[Rob_R]

I mean what person drives around with the battery voltage screen display on their console?

I do! I find it quite interesting to observe what the smart battery system is up to. One observation I have is when I take the batteries off of the charger/maintainer, the batteries remain at an almost constant voltage at 13.6 - 13.8V for an hour or two while driving around town running errands. The voltage reading will slowly drop to 12.7 - 12.8V with zero smart battery charging activity into day two. By zero smart battery charging activity, I mean the batteries show no IBS activity when off throttle or braking. Usually by day three the IBS kicks in and I see the normal fluctuation that is ambient temperature dependent as far as maximum voltage when off throttle or braking. When the system has the throttle applied the voltage will not go lower than 12.7 - 12.8V.

Sponsored

 

[Andy29847]

Interstate Battery System of America, Inc., a.k.a. Interstate Batteries, is a US privately owned battery marketing and distribution company. It markets automotive batteries manufactured by Brookfield Business Partners, Exide Technologies, and others through independent distributors

Exactly. Mopar, like Interstate, buys their batteries. Like illustrated with the Interstate photo, all batteries of the same size are not the same. The quality of the Mopar batteries and the design of the battery systems in our Jeeps are called in to doubt by the number of questions and complaints from Jeep owners. I've never had another vehicle where batteries were an issue.

 

[Lost1wing]

I poke around and view different page. ESS, oil temp, oil pressure and Coolant temp mostly. I like to see normal indications. Surprise lights and warning are never a good sign. I'll even pull up the vehicle info page up on the radio display ( no all models). All most never, will you find me singing along to a Taylor Swift song with the radio page up, almost.

 

[Lunentucker]

Exactly. Mopar, like Interstate, buys their batteries. Like illustrated with the Interstate photo, all batteries of the same size are not the same. The quality of the Mopar batteries and the design of the battery systems in our Jeeps are called in to doubt by the number of questions and complaints from Jeep owners. I've never had another vehicle where batteries were an issue.

 

[Jeeperjamie]

My thoughts are Jeep engineering knows more than most on this thread and pulling fuses and bypassing batteries doesn't seem smart. I had my main battery replaced at 54,000 miles, still have a perfectly working Aux battery at 83,000 miles. Another though is pulling fuses and bypassing batteries seem like a good reason for your insurance to deny paying out on your jeep if it burns to the ground or a good reason for the dealership to not cover something that may be under warranty. Just saying!

 

[Andy29847]

My thoughts are Jeep engineering knows more than most on this thread and pulling fuses and bypassing batteries doesn't seem smart. I had my main battery replaced at 54,000 miles, still have a perfectly working Aux battery at 83,000 miles. Another though is pulling fuses and bypassing batteries seem like a good reason for your insurance to deny paying out on your jeep if it burns to the ground or a good reason for the dealership to not cover something that may be under warranty. Just saying!

I am an old guy who is staying inside because it's cold and wet outside. In addition to that, I'm normally contrary. Given the situation, I can't help but comment to JeeperJamie (all in good humor) that you have modified your Jeep. Don't be so judgmental if I modify mine.

Also, congrats on the long service life of your aux battery. You have been lucky. I'd suspect that a contributor to the long service life is that you aux battery isn't doing much.

 

[Jeeperjamie]

I am an old guy who is staying inside because it's cold and wet outside. In addition to that, I'm normally contrary. Given the situation, I can't help but comment to JeeperJamie (all in good humor) that you have modified your Jeep. Don't be so judgmental if I modify mine.

Also, congrats on the long service life of your aux battery. You have been lucky. I'd suspect that a contributor to the long service life is that you aux battery isn't doing much.

All good, Winch, and 4 auxiliary lights are all ran by it through switches. I use it they are just designed to last. My neighbors JL has over 120,000 miles on his aux battery.

 

[Gatorac]

When I made this simple video I thought that taking the AUX battery offline would disable ESS. That part is wrong, but I don't feel like making another video.

Wait, what? I used your video, disconnected the ground cable and pulled fuse 42. ESS has not activated since. No errors either. I did this months ago. I never push the button. Maybe it's a 2020 thing. IDK. I'm happy and the aux battery will ultimately be removed when I have the time for that project.

 

[Andy29847]

All good, Winch, and 4 auxiliary lights are all ran by it through switches. I use it they are just designed to last. My neighbors JL has over 120,000 miles on his aux battery.

I'm glad you are happy. If I was going to try and bust your bubble, I'd start by telling you that the aux battery is not the sole power source for the aux switches. In fact. The 2 batteries in the Jeep are almost always connected together.

 

[Jeeperjamie]

I'm glad you are happy. If I was going to try and bust your bubble, I'd start by telling you that the aux battery is not the sole power source for the aux switches. In fact. The 2 batteries in the Jeep are almost always connected together.

Then your point is pointless, just like your not a jeep engineer so why would I listen to what someone says in a thread on a forum.

 

[Andy29847]

Then your point is pointless, just like your not a jeep engineer so why would I listen to what someone says in a thread on a forum.

Clever repartee!

 

[Lunentucker]

Wait, what? I used your video, disconnected the ground cable and pulled fuse 42. ESS has not activated since. No errors either. I did this months ago. I never push the button. Maybe it's a 2020 thing. IDK. I'm happy and the aux battery will ultimately be removed when I have the time for that project.

Interesting. Mine activated a couple of times and I got in the habit of pushing the button at startup.
Keep in mind that it's fairly finicky about meeting certain criteria to be able to activate.
Warmed engine, not too cold or hot outside, firm braking to a stop.

 

[ShadowsPapa]

One observation I have is when I take the batteries off of the charger/maintainer, the batteries remain at an almost constant voltage at 13.6 - 13.8V for an hour or two while driving around town running errands. The voltage reading will slowly drop to 12.7 - 12.8V with zero smart battery charging activity into day two.

The batteries aren't remaining at that voltage - the truck is replacing what was taken out during the startup sequence - via starter and electronics and so on. It also uses battery temperature and historical data sent to the BCM from the IBS via the Lin to determine how to set voltage.
It will always make up for what you take out during the startup sequence of events, but once that's done, if it's satisfied based on the data, current voltage and other factors, it will lighten the load on the engine accordingly. It's in maintenance mode at that point.

I'd start by telling you that the aux battery is not the sole power source for the aux switches.

The aux battery isn't the source at all - it's the pair, however, it's more directly taken from the crank/main battery. Note that if you have aux switches, you have a larger main battery.......
The load is rather split on the two batteries.
I need to set up for more experiments when health allows, but past experimenting and monitoring shows that during an ESS stop event, BOTH batteries supply power - it's a split load in a real sense, electronics getting the direct to aux connection while the main battery supplies more power-hungry things. I watched the two battery voltages drop almost in lockstep. By the time I was ready to let off on the brake, the main battery was down to only about a tenth of a volt higher than the aux battery.

 

[ShadowsPapa]

I've never had another vehicle where batteries were an issue.

Amazing. That's sure different than my experiences and that of those I've talked to.
Referring back to while I was in a NAPA store a few months back - getting a battery replaced (one that lasted almost 4 years! Amazing! - but for a 1982 car) guys were in there complaining that they were having trouble getting a battery to last even 4 years. They were not Jeep people.
My son had a problem with his Fusion after about 3 years - battery failure.
4xe owners complain of battery issues - no, not the HV battery, but the 12 volt battery.
And the kicker is - there is no ESS and no aux battery! The 12 volt battery, exactly like the main battery in our JTs, doesn't last. In some cases, they don't make it a year, others are saying that after 2 or 3 years the 12 volt battery craps out.
So we can't blame ESS or the aux battery or whatever.
It's a combination of things, a stack-up of issues.
Guys with ordinary cars and trucks complaining about battery life.
My son's Fusion - battery died pretty quickly.
4xe owners having batteries fail after anywhere from 2 months to 2 or 3 years.
And yet the batteries in my son's Compass weren't problematic. The batteries in my wife's WK2 went 3 years and crapped out. Battery in my SX4 - almost 4 years and crapped out.

 

[ShadowsPapa]

All most never, will you find me singing along to a Taylor Swift song with the radio page up, almost.

Crap, I can't even get away from her name or images or some crap about her on a Jeep forum! Good grief, sex/sultry sells. Ugh, can't stand her. It's hard to even pull up a browser page with current news without her showing up. Enough already!

Sponsored