Auto start stop question

[Chunky White]

I went out to get some food earlier and the ESS didn't work so I am guessing my battery lost some charge overnight. I will check the batteries soon

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[Hootbro]

There is a big list in the owners manual of things that can keep the start/stop from engaging.

Next to battery condition, people overlook during the summer months that having their A/C on Max will inhibit the system.

 

[ShadowsPapa]

I went out to get some food earlier and the ESS didn't work so I am guessing my battery lost some charge overnight. I will check the batteries soon

If it was mine, this is what i'd be looking for/at, and what I'd do - of course it's not, so......
To reiterate:
Volt meter (anything that can read down to the tenth of a volt with reasonable accuracy - doesn't need to be a $300 + Fluke)
Test voltage at main battery after the truck has sat for a few hours - not running. Volt meter leads on main battery posts.
Test with engine running - likely will show similar to cluster voltage display but I've found sometimes a bit of difference - not sure where exactly they sense the voltage from.

If it's low - say 12.4, I'd charge both batteries with a decent charger of at least 10 amps. Let it go through all 3 charging phases. Yeah, it's not like let's throw a voltage at it and push it full. A good charger will charge an AGM with 3 phases. There will be various times of constant voltage and times of constant amperage, declining voltage and so on. It can take hours so be ready for a time where the truck can sit.

If you can - IF - leave the batteries disconnected after the charge. Check voltage to ensure they made it up to at least 12.7-12.8 volts. Mine make it to about 13.0 then settle to 12.8 after an hour or so.
Let them sit about 6-12 hours if you can and check voltage. If, disconnected, they are no longer reading 12.7, it's not good. Capacity is gone, they are self-discharging too fast.

If you don't have time to let it sit like that, reconnect and check later but know the parasitic load of the truck systems will draw batteries down. But if they have decent capacity, they'll still stay up there 12.6 for quite a while.

There are two things about batteries that can be confusing -
CCA is a sprint. How fast can you go for a short period before dropping below a certain voltage.
Capacity is a marathon. How long can you last with a load before dropping below a certain voltage.
As batteries age, they may crank the beast just fine and you hear it spin 2 or 3 times, fire and run and gee, that battery sure is good! No, it's not - because a few more seconds the capacity would not be there and the battery would no longer crank that engine.
After being low for so long, they lose capacity - may still spin it over and start, but the ability to run a marathon is gone. They can never be charged up to the full amp hour capacity they had. The more they sit with voltage in the low 12s, the fewer cycles they have (meaning you lose hundreds of times it will start the engine) and the less likely it can start it when cold.

I'm grossly over-simplifying and taking shortcuts, but it's about the easiest way.

Anyway - batteries with typical modern use are seeing only about 3 years these days. I refer back to the customer in the NAPA store when I was there - he was complaining that he can't get more than 4 years out of a battery. Jeeps seem to do well at 3 years.
A truck made in 2019 or 2020 is either past, or going on 3 years. And if the batteries haven't been kept fully charged all the time, they lose lifespan.
I'm in my shop, don't have access to my server files, but have some info from one of the battery makers on that inside.
Interesting thing about some "floaters" or "maintainers" as well - they gave an example of a battery that was only at 85% when the float charger was put on - they said that after weeks - you'd come back to a battery still sitting at 85% and some lose lifespan.

 

[ShadowsPapa]

There is a big list in the owners manual of things that can keep the start/stop from engaging.

Next to battery condition, people overlook during the summer months that having their A/C on Max will inhibit the system.

Yes, that for sure - max AC - but it will work with normal AC. Just not max. I've got a tech doc showing over 20 factors that will never show up on the screen as a reason as well.
So if you run max AC, ESS won't work as it figures "I can never fulfill that request" and won't shut off.
IF you run in auto mode or just plain AC mode, it will work ONCE cabin temperature is reached. If you set it to 70 degrees you may see stops/start not ready, cabin heating/cooling" or similar, but once it reaches that 70 degrees as far as it is concerned, it will trigger ESS if all of the list of other factors match their true/false criteria.

 

[Chunky White]

I had the windows down with the AC off and was watching the ESS screen to see whether it would go to ready or not. It said battery charging the whole time.

 

[ShadowsPapa]

I had the windows down with the AC off and was watching the ESS screen to see whether it would go to ready or not. It said battery charging the whole time.

I'd run some voltage tests then. Maybe try charging and go from there. Bet they r near end of life. If u do charge, fully disconnect the IBS for 10-15 minutes to reset it before reconnecting everything. That helped my 2020 for quite a while

 

[Lost1wing]

I'd run some voltage tests then. Maybe try charging and go from there. Bet they r near end of life. If u do charge, fully disconnect the IBS for 10-15 minutes to reset it before reconnecting everything. That helped my 2020 for quite a while

I'd have to look back at my posts, but my 2020 is still sporting the original batteries. I had the battery charging message on almost all of the time. I did the ibs reset along with charging both batteries independently and the start stop is still working like it should. Even after a week of being parked it say start stop ready after the engine warms up.

 

[ShadowsPapa]

I'd have to look back at my posts, but my 2020 is still sporting the original batteries. I had the battery charging message on almost all of the time. I did the ibs reset along with charging both batteries independently and the start stop is still working like it should. Even after a week of being parked it say start stop ready after the engine warms up.

That's what I'd try in this case. IBS reset and full charge of each battery with agm charger. Worked on my 20. (And your's too)

 

[Chunky White]

sorry for never replying but I have found that the batteries are charging enough on longer drives that the auto start stop works until I sit and listen to the radio with the engine off for a while and then it doesn't work for a while. I believe my sitting and listening to the radio while on lunch is the reason it doesn't work and it just takes too long for the batteries to recharge to the point it works again. I don't even like the feature but was surprised that I worked after my last oil change when it hadn't in months

 

[ShadowsPapa]

sorry for never replying but I have found that the batteries are charging enough on longer drives that the auto start stop works until I sit and listen to the radio with the engine off for a while and then it doesn't work for a while. I believe my sitting and listening to the radio while on lunch is the reason it doesn't work and it just takes too long for the batteries to recharge to the point it works again. I don't even like the feature but was surprised that I worked after my last oil change when it hadn't in months

Use of radio keeps other systems "awake" and takes a toll on the batteries.
You can likely count on the batteries not living a long life. (especially with a 2020)

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