2007~2015 CX-9 Intermittent battery indicator light

[FlogDolfinG]

Fairly new to the forum and to CX-9’s. Just bought a 2011 AWD Touring a couple weeks ago, 138k miles. Reading up on the potential problems and quirks (getting ready to change the PTU fluid soon).

Anyway, I’m wondering if anyone here would have had a similar situation as what has happened over the last couple days. In brief, the battery indicator light has been coming on intermittently. It seems to be when I’m driving it for a long time and it is hotter outside. I have a voltage gauge on my power outlet on the front console, and the voltage is reading a fairly steady 13.5 - 13.8 volts, regardless of if the light comes on or is off. For instance today, I drove a long trip (3hours) and it was coming on for ~15-30 seconds, then would go off for a few minutes, then on….etc. the temperature outside was in the high 70s-80. Then it seemed like when the temperature got lower, like low 70s or below, it stopped happening.

Again, looking at my voltage gauge, there was no apparent voltage difference between light on and off. The battery isn’t showing any sign of being weak (engine starts fine). I have read where a loose alternator belt can cause intermittent charging issues, but I would assume I would see a voltage drop if that were happening?

 

[puma]

Usually yes, the voltage should lower to 12,7 if the alternator stops working. Weird issue, i suppose it has to do with what reads the voltage but no idea what it is

 

[Maxmodem]

I had same issue after buying my 2009 cx9. It turned out when someone replaced the alternator they didn't tighten up one of the bolts on it that connected to a power cable. I don't know if you have the same issue but it would be worth checking the alternator to see if everything is bolted down tight.

 

[kornholio]

I would like to know what is the normal charging voltage when the alternator is operating properly?

 

[hw4ng3r]

I would like to know what is the normal charging voltage when the alternator is operating properly?

Typically, 12V batteries have a "resting voltage" (fully charged with car off) ~12.6 V and when the engine is running (without issues), it'll rise to somewhere in the 13.5 to 14.5 V.

The battery needs at least ~13 V to charge.

 

[PTguy]

A lead acid nominal 12 volt battery is 100% charged at 12.6 volts. As said above charging voltage to force power into the cells is in the high-13 to mid-14 volt range. The noted 13.5 to 13.8 volts is good. I don't know where the alternator indicator is connected, as said above, you might look for loose or dirty connections.

 

[yrwei52]

Fairly new to the forum and to CX-9’s. Just bought a 2011 AWD Touring a couple weeks ago, 138k miles. Reading up on the potential problems and quirks (getting ready to change the PTU fluid soon).

Anyway, I’m wondering if anyone here would have had a similar situation as what has happened over the last couple days. In brief, the battery indicator light has been coming on intermittently. It seems to be when I’m driving it for a long time and it is hotter outside. I have a voltage gauge on my power outlet on the front console, and the voltage is reading a fairly steady 13.5 - 13.8 volts, regardless of if the light comes on or is off. For instance today, I drove a long trip (3hours) and it was coming on for ~15-30 seconds, then would go off for a few minutes, then on….etc. the temperature outside was in the high 70s-80. Then it seemed like when the temperature got lower, like low 70s or below, it stopped happening.

Again, looking at my voltage gauge, there was no apparent voltage difference between light on and off. The battery isn’t showing any sign of being weak (engine starts fine). I have read where a loose alternator belt can cause intermittent charging issues, but I would assume I would see a voltage drop if that were happening?

If the charging voltage is fine, the other reason which triggers the “battery warning indicator” is the inferior or failing built-in rectifier in the alternator.

Since you just bought your 2011 AWD Touring, other than changing the gear lube in the front transfer case (PTU) ASAP and more frequently (might as well the rear differential), not sure how are you going to prevent the inevitable water pump failure which could ruin your engine. May be you should change the “internal” “timing-chain driven” water pump now ($$$$$) unless you have a proven document that the water pump on your 3.7L V6 has been replaced.

 

[FlogDolfinG]

Water pump…I guess I’ll deal with that if ever it happens.

Update on the light….drove another long trip, and it was pretty warm outside, and it didn’t come on once. So, it’s fixed for now I guess. I didn’t do anything to it, so…

 

[yrwei52]

Water pump…I guess I’ll deal with that if ever it happens.

It will happen. If you don’t want to deal with it right now, just change the coolant with correct type and the engine oil and hope the best, Check the coolant and oil frequently for any sign of mixing, or send the old oil sample to a lab for UOA checking for coolant existence. Remember if the “internal” water pump in your V6 is leaking and you let the oil mixed with coolant in the engine long enough, the whole engine is ruined.

Update on the light….drove another long trip, and it was pretty warm outside, and it didn’t come on once. So, it’s fixed for now I guess. I didn’t do anything to it, so…

Nothing will fix it by itself. For now you can just monitor the Battery Warning Light and hope it won’t lit.