BAD IBS SENSOR OR SOMETHING ELSE....

[FlatRonnie]

So I've been getting the infamous battery charge system light. And this is the second time in less than a year that it has come back. The first time I replaced both auxiliary and main battery at the same time. Made sure they were trickle charged to 100% first. I know about the issues with the auxiliary battery start stop system, but I feel like I have something else going on, as both batteries and alternator just tested good.

I recently performed a parasitic draw test after letting the jeep sleep overnight and making sure the doors and hood were "latched". I was getting a draw of 50 to 60 mA. Which seems to be pretty normal.

Currently I have the auxiliary battery deleted temporarily. Last night I trickle charged the main battery till it was 100%, and I checked the voltage this morning before I left for work and it was at 13.11 volts. I drove 15 mi to work about 25 minutes and 15 mi back home, about 30 minutes. I checked the voltage and it was at 12.85 volts. Is that normal for it to drop like that? Is it because I just didn't have enough drive time? I'm wondering if maybe my IBS sensor is bad?

Know one other note, when I pulled my auxiliary battery there was corrosion on the positive terminal. After I pulled it I trickle charged it and it did lose voltage overnight. The manufacturer "Odyssey" Said it could be bad so I should have it replaced, I will also replace the main battery at the same time.

If it's not the IBS sensor, what else could be causing my issues?

Thanks in advance!

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[Lost1wing]

The difference in voltage levels could just be the time coming off the charger, being either the alternator or battery charger. The temperature coyld also be a factor. When trying to sample like you did, charge one afternoon and retest in the morning when all has cooled off. This will simulate more or less like a normal drive cycle. The difference will be, that after charging with the charger the battery should be completely charged. A normal drive cycle may not leave you with a fully charged battery.
When you charge a battery with a charger there will be residual voltage left over. The battery should rest a while before testing.

 

[ShadowsPapa]

The first time I replaced both auxiliary and main battery at the same time. Made sure they were trickle charged to 100% first.

Why didn't you properly charge them instead of a trickle? Trickle chargers, maintainers, tenders and so on aren't the same.
Use a real battery charger capable of 10amps and charge it - don't trickle them.
Stop charging with a trickle charger. Get and use a good AGM battery charger.

Disconnect everything - pull the IBS.
Charge with a real charger - not trickle - both batteries.
Let them sit a while and then check the voltage. Should be at ~12.8 volts
Put everything back.
This puts the IBS back on correctly charged batteries. It will then take roughly 4 hours of sitting, with the fob clear away from it to prevent things from waking up, and a startup cycle or two, for the IBS to learn.

When the IBS goes bad, it will almost always store a code.
13.11 volts is a surface charge. (depending on the battery, some actually run close to that normally)
12.8 (or "about that") is correct for a fully charged AGM depending on BRAND and so on. Some will check higher, some on the lower end of that, but a target of ~12.8 is good.

 

[FlatRonnie]

When trying to sample like you did, charge one afternoon and retest in the morning when all has cooled off.

That makes sense. I will try this and see what I get. Thank you!

 

[FlatRonnie]

Why didn't you properly charge them instead of a trickle? Trickle chargers, maintainers, tenders and so on aren't the same.
Use a real battery charger capable of 10amps and charge it - don't trickle them.
Stop charging with a trickle charger. Get and use a good AGM battery charger.

Honestly, you're the first person that has mentioned this. I Figured that if I use a battery maintainer and it brings it up to 13.11 volts and says it's fully charged that was good? The only times ever use a maintainer really was when I first got the batteries, and recently when I was trying to diagnose. Do you have any recommendations for a decent battery charger?

I will try your recommended procedures. Do you have any idea what would have cause the P00FD (battery ""b"" state of charge performance) Code in the first place? Keeping in mind that I had both batteries replaced at the same time less than a year ago...

Thank you for the help!

 

[ShadowsPapa]

Honestly, you're the first person that has mentioned this. I Figured that if I use a battery maintainer and it brings it up to 13.11 volts and says it's fully charged that was good? The only times ever use a maintainer really was when I first got the batteries, and recently when I was trying to diagnose. Do you have any recommendations for a decent battery charger?

I will try your recommended procedures. Do you have any idea what would have cause the P00FD (battery ""b"" state of charge performance) Code in the first place? Keeping in mind that I had both batteries replaced at the same time less than a year ago...

Thank you for the help!

Battery "B" is the auxiliary battery. It's failing a test during startup.
It means the battery isn't charged or staying charged when the PCM does a quick battery check during cranking.
Might be time for a load test - batteries can have a good voltage at rest, but drop like a rock with any load at all.

 

[FlatRonnie]

Battery "B" is the auxiliary battery. It's failing a test during startup.
It means the battery isn't charged or staying charged when the PCM does a quick battery check during cranking.
Might be time for a load test - batteries can have a good voltage at rest, but drop like a rock with any load at all.

Ok , I have an Odessey AUX battery, which I will be replacing. I did notice upon removal that there was exterior corrosion on the positive terminal. Bad connection maybe?

 

[ShadowsPapa]

Ok , I have an Odessey AUX battery, which I will be replacing. I did notice upon removal that there was exterior corrosion on the positive terminal. Bad connection maybe?

Yeah, very possible.

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