Aux Battery is OK, what else could cause "Start/Stop not Ready, Battery Charging?

[badglad]

Aux and main battery fine and fully charged. But always have "Start/Stop not ready, Battery Charging" even after driving many miles. What else can I look at?

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[sharpsicle]

This is almost always a low voltage situation, which 99% of the time leads to the batteries.

How did you determine the health of the batteries?

 

[kb5zcr]

If one of the "hood closed" plunger switches are bad that will cause the start/stop to stop working.
I think the left one is the one that will turn it off.

 

[badglad]

This is almost always a low voltage situation, which 99% of the time leads to the batteries.

How did you determine the health of the batteries?

Across the main battery terminals is 12.5V and across N1 to chassis ground measures 12.51V. The Aux battery is brand new, in fact the old aux battery measured good (so that was a waste of time and money)

 

[badglad]

If one of the "hood closed" plunger switches are bad that will cause the start/stop to stop working.
I think the left one is the one that will turn it off.

I swapped the two switches with the circuits they control and will see if that changes anything (the contacts are too hard to reach with an ohmmeter)

 

[badglad]

Across the main battery terminals is 12.5V and across N1 to chassis ground measures 12.51V. The Aux battery is brand new, in fact the old aux battery measured good (so that was a waste of time and money)

The alternator is putting out 14.3+ volts

 

[badglad]

I swapped the two switches with the circuits they control and will see if that changes anything (the contacts are too hard to reach with an ohmmeter)

No change so the hood closed switch must be good.

 

[Mr._Bill]

The alternator is putting out 14.3+ volts

That means it is trying to charge the batteries. Once they are fully charged, output from the alternator will drop to around 13 volts.

Separate the negative cables and separately charge each battery. Take a voltage reading when charging is finished. Let them sit overnight with no load. Fully charged, with nothing connected, each battery should read real close to 12.8 volts. If there is much of a drop while sitting with no load, the battery needs replaced.

 

[sharpsicle]

Across the main battery terminals is 12.5V and across N1 to chassis ground measures 12.51V. The Aux battery is brand new, in fact the old aux battery measured good (so that was a waste of time and money)

Unfortunately this isn't enough to determine the state of the batteries.

You'll want to isolate each one, charge it, let it sit (say overnight or so), and then measure the voltage. How much it retains will give you some more useful information.

I'm willing to bet that, since you replaced the aux, that replacing the main would fix your issues. Heck, I'd even wager the aux was never the problem but rather it was the main the whole time.

 

[Lost1wing]

The above should reset the IBS by leaving the battery cables disconnected while you charge the batteries. If you don't plan on recharging the batteries right away, disconnect the IBS for 20 minutes. This should be done with fully charged batteries however.

If you charge your batteries in the vehicle with everything connected, be sure to clamp your negative on top of the IBS and not on the negative post.

If you charge the independently, clamp your charger positive to the main positive and leave it there. Then you move your negative clamp to the isolated aux negative until it is finished. Then move the negative charger clamp to the main negative post until it is charged. You can still disconnect the IBS connector. Be sure to keep the aux ground cable isolated.

 

[ShadowsPapa]

That means it is trying to charge the batteries. Once they are fully charged, output from the alternator will drop to around 13 volts.

Separate the negative cables and separately charge each battery. Take a voltage reading when charging is finished. Let them sit overnight with no load. Fully charged, with nothing connected, each battery should read real close to 12.8 volts. If there is much of a drop while sitting with no load, the battery needs replaced.

This is a great start.
Charge each independently with a proper AGM charger - and not a trickle charger. You need something with some push, more than a couple of amps.
While charging, the IBS will be FULLY disconnected and set aside.
With the batteries not connected to anything, after charging, observe voltage.
There will be a surface charge, often over 13 volts, you can remove it with a load of some sort for a few seconds. They should settle at 12.8 volts (some at 12.9 volts)

If they hold that over some time without being connected, it's a good sign, but not a perfect tell.
Only a real load test will give the full story.

If one of the "hood closed" plunger switches are bad that will cause the start/stop to stop working.
I think the left one is the one that will turn it off.

It will not cause his message of "battery charging". It will simply disable it with no message, or perhaps a hood open message - so this isn't relevant to his issue at all.

Across the main battery terminals is 12.5V and across N1 to chassis ground measures 12.51V. The Aux battery is brand new, in fact the old aux battery measured good (so that was a waste of time and money)

12.5 isn't fully charged - it's only about 3/4 charged or so. If one of the batteries is new and if it was properly charged before installing, then it's dropped for some reason.

(and that brings up a thing I see over and over - why in @#$% do people install batteries without charging them FIRST???
That's a rule, always, always has been. Charge batteries - yes, new ones, before installing them.

 

[tastetickles]

My recent research on aux battery and main battery points to main battery issues if it says “blaa blaa, Battery charging”. And AGM batteries if fully charged should be around 12.8 volts.

 

[ShadowsPapa]

My recent research on aux battery and main battery points to main battery issues if it says “blaa blaa, Battery charging”. And AGM batteries if fully charged should be around 12.8 volts.

Just don't get your research from forums LOL.
AGM is typically 12.8 but some brands seem to settle around 12.9. The thing is, the numbers are rounded anyway. Even the older non-AGM 12.6 was truly above that as it was rounded down.

I resolved all ESS and battery issues on my 2020 by charging each battery and resetting the IBS. It was fine after that.

 

[clarkhogan]

I had this exact same problem. I had replaced both batteries and had alternator tested. The solution was to separate out the intelligent battery sensor for about 20 minutes to reset it.

 

[ShadowsPapa]

I had this exact same problem. I had replaced both batteries and had alternator tested. The solution was to separate out the intelligent battery sensor for about 20 minutes to reset it.

Always reset IBS with a battery change. It needs to learn the new batteries (also best to charge new batteries before install. Don't understand why so few do).
You dun exactly what needed to be dun.

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