Stop/Start Not Ready-Battery Charging

[THAW]

Recall the "Battery Voltage" indicator on the Cluster's EVIC is a misnomer. It does not show instantaneous battery voltage on the terminals, it really shows the alternator's output 'effort'. The units should be in work, not potential. But hey, this is easier to visualize just based on a simple metric than actual physics. Dumb down the presentation for us simple minded consumers.

The Battery Voltage indicator DOES show voltage at the battery terminals. The voltage metric shows ACTUAL physics, the opposite of dumbing down the presentation (such as with an estimated charge percentage). But, yes, with the motor running, voltage at the terminals is not resting battery voltage since the battery is in circuit with the alternator.

Don't forget the indicator works with the engine off, so voltage can be read without the charging effect. It can be useful to watch how low voltage dips during startup to get a sense of battery health.

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[THAW]

Thanks, I'm going to get the Service Manager to read and check these items.

"The batteries can go bad independently, but they will run down (or drain) together. Except when a bad battery relay (PCR) or or a blown PCR (ESS) fuse separates them, which will also prevent the Aux battery from charging."

If these items are fine. I will replace both batteries with Motomaster Eliminators. The company that sells Odyssey here leave me with no confidence in the after sales process.

It's true your ESS battery won't charge if your PCR relay is permanently open or your PCR (ESS) fuse is blown, but your vehicle would soon stop running at all.

 

[AZJeepGuy]

I will replace both batteries with Motomaster Eliminators.

Link? I did a search and got tires, battery tester and a couple other things.

 

[Altitude2020]

It's true your ESS battery won't charge if your PCR relay is permanently open or your PCR (ESS) fuse is blown, but your vehicle would soon stop running at all.

Well I will see Monday, let the dealership check the items. It's been doing this for 2 years. It is just getting worse.

 

[Altitude2020]

Link? I did a search and got tires, battery tester and a couple other things.

https://www.canadiantire.ca/en/pdp/...r-h7-l4-battery-800-cca-0109420p.0109420.html

 

[Altitude2020]

https://www.canadiantire.ca/en/pdp/...r-h7-l4-battery-800-cca-0109420p.0109420.html

https://www.canadiantire.ca/en/pdp/...xiliary-battery-200-cca-0102060p.0102060.html

 

[The Last Cowboy]

The Mopar batteries are a crap shoot as far as quality goes. And, it seems many dealers can't or won't solve this issue.

When this issue happened to mine, I went to O'Reilly's and bought two brand new batteries at my own expense. Yeah, it was $300, but I didn't have to make an appointment, drop it off, wait for them to get around to it, then wind up with maybe one new battery and the other charged, only to have the issue keep popping up.

Since I did it on my own, there have been zero battery, charging, ESS issues for over a year.

What I have learned from all the reading here is that next time this happens, or as soon as I get the ESS not ready, battery charging message, I will eliminate the aux battery.

 

[Altitude2020]

The Mopar batteries are a crap shoot as far as quality goes. And, it seems many dealers can't or won't solve this issue.

When this issue happened to mine, I went to O'Reilly's and bought two brand new batteries at my own expense. Yeah, it was $300, but I didn't have to make an appointment, drop it off, wait for them to get around to it, then wind up with maybe one new battery and the other charged, only to have the issue keep popping up.

Since I did it on my own, there have been zero battery, charging, ESS issues for over a year.

What I have learned from all the reading here is that next time this happens, or as soon as I get the ESS not ready, battery charging message, I will eliminate the aux battery.

I will probably end up replacing both batteries. The Jeep just has to last 2 more years Hopefully with little issues. We have decided to sell it that time since it will have 1 year left on the extended warranty. In 2026 I will then look at what's on the market.

 

[AZJeepGuy]

But before replacing the batteries, don't you want to find out why the aux battery isn't charging?
Like a relay isn't opening or closing, battery isn't getting charged, but it is giving you the correct message. Bad relay, no charge.
The dealer has replaced two aux batteries and now two main batteries.
Is it possible, for trouble shooting purposes, to turn off the ESS? Like if they turned it off and there were no issues with either battery, them they would know the issue is somewhere in the ESS system. I want the dealer to do it to isolate the issue. My last battery was less than 30 days old and had damage.

 

[Altitude2020]

I will probably end up replacing both batteries. The Jeep just has to last 2 more years Hopefully with little issues. We have decided to sell it that time since it will have 1 year left on the extended warranty. In 2026 I will then look at what's on the market.

But before replacing the batteries, don't you want to find out why the aux battery isn't charging?
Like a relay isn't opening or closing, battery isn't getting charged, but it is giving you the correct message. Bad relay, no charge.
The dealer has replaced two aux batteries and now two main batteries.
Is it possible, for trouble shooting purposes, to turn off the ESS? Like if they turned it off and there were no issues with either battery, them they would know the issue is somewhere in the ESS system. I want the dealer to do it to isolate the issue. My last battery was less than 30 days old and had damage.

Yes, I posted this in a previous post.

Thanks, I'm going to get the Service Manager to read and check these items.

"The batteries can go bad independently, but they will run down (or drain) together. Except when a bad battery relay (PCR) or or a blown PCR (ESS) fuse separates them, which will also prevent the Aux battery from charging."

If these items are fine. I will replace both batteries with Motomaster Eliminators. The company that sells Odyssey here leave me with no confidence in the after sales process

 

[The Last Cowboy]

They are two different size batteries. One will draw off the other if one gets low. It's almost always the aux drawing off the main. It's not a well thought out system, and is probably the number one cause of complaints.

There are plenty of threads on here about how to change both batteries, or eliminate the aux battery from the charging system. If you eliminate it, it is best to buy a stop start delete device of some sort.

Also, I highly recommend an H7/94R battery for the main replacement, if you don't already have one. If you have a tow package and/or aux switches from the factory, you likely already have the larger main battery.

Sorting out the charging issue will often take care of a lot of other lesser electrical gremlins, as many of the vehicle functions are sensitive to voltage.

If you still have electrical gremlins after battery replacement, the the CANbus star connector behind the glove box is another thing to look at replacing.

Most dealer "techs" are nothing more than guys who pull codes and replace parts. The few skilled and experienced mechanics are often working on the larger, more complicated jobs and don't want to bother with a small paying job like electrical issues.

All of this is easy to do yourself, if you follow some of the threads here. Plus, there's the satisfaction that comes from doing it yourself and doing it right.

Much to read here,

https://www.jlwranglerforums.com/forum/forums/battery-talk.195/

 

[THAW]

But before replacing the batteries, don't you want to find out why the aux battery isn't charging?
Like a relay isn't opening or closing, battery isn't getting charged, but it is giving you the correct message. Bad relay, no charge.
The dealer has replaced two aux batteries and now two main batteries.
Is it possible, for trouble shooting purposes, to turn off the ESS? Like if they turned it off and there were no issues with either battery, them they would know the issue is somewhere in the ESS system. I want the dealer to do it to isolate the issue. My last battery was less than 30 days old and had damage.

Again, if the ESS/aux battery isn't receiving charging current from the alternator (bad relay, blown fuse) the vehicle will stop operating altogether after a short time.

When the ESS battery begins to fail, the vehicle disables ESS. There's no need to turn it off to test anything.

 

[AndySpill]

But before replacing the batteries, don't you want to find out why the aux battery isn't charging?
Like a relay isn't opening or closing, battery isn't getting charged, but it is giving you the correct message. Bad relay, no charge.
The dealer has replaced two aux batteries and now two main batteries.
Is it possible, for trouble shooting purposes, to turn off the ESS? Like if they turned it off and there were no issues with either battery, them they would know the issue is somewhere in the ESS system. I want the dealer to do it to isolate the issue. My last battery was less than 30 days old and had damage.

A way to turn the ESS system off on you dual AGM battery JL is to disconnect the black cable on the main battery's negative post whose distal end is not the body ground on the passengers front quarter panel, but rather the other factory cable, whose distal end is the negative terminal of the ESS battery.

Attempt to crank. Expect to fail the first time. Your vehicle tried to test the ESS battery for current and got nothing because the ESS battery is disconnected as a result of the prior step.

Try the crank again. This time, because it is NOT a 2018 lacking TSB 18-092-19, it should succeed, provided your main battery has ample power, turning the ESS system off as you wish, and displaying the ESS off icon (a letter "A" with a near circle around it followed by an exclamation point) in the dash.

Restoration of the ESS system comes at the next cold crank, if any, that the ESS battery is both connected back, and has ample power.

Note how I most definitely left out the step of pulling Fuse 42. Don't. It is not part of this particular procedure as it might be for permanently removing the ESS battery from the electrical schematic of the vehicle.

@THAW writes " When the ESS battery begins to fail, the vehicle disables ESS."

In a manner of speaking he's correct, as a vehicle whose factory connected ESS battery gets low enough that it can't crank certainly doesn't engage its ESS system, much as this happens only after the battery first begins to fail. Fortuntately for again, all dual AGM battery models but early 2018s without TSB 18-092-19, which with a dead and factory connected ESS battery will leave you stranded, the second crank attempt does as discussed above.

 

[Jenkins46]

Have any of you all checked the battery sensor on the negative battery post on the main battery my 2020 wrangler been showing not ready i unplug the sensor for a couple hours then plug it back in and the start stop works again

 

[Altitude2020]

I had the aux battery replaced, still have Start/Stop not ready battery charging message. I'm going for a 200 km trip today see if it clears. If not, back to the dealership on Thursday. Not much I can do since it's under warranty. I mentioned the CanBus connector.

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