Location: Phoenix, AZ

Hi all. Trying to avoid the dealership like the plague.

Going on ~2 weeks now, my wife's CX-9 hasn't kept a battery charge. Battery was checked good by a shop on the initial instance and I've mostly had it on a tender when we weren't using since then. I ought to check at a shop again if it is still holding enough charge. If not on the tender, it will 100% not start after sitting overnight. In fact, it had a full charge this afternoon...my wife took it out for a 15 min drive, 1 hour appt and it wouldn't start on retry.

Charges to: 12.6
Alternator to: 14
Meter connected in series: 1.9a draw (after sitting for 30+ minutes).
---> Removing Fuse10 (Interior Box), 15a: drops to .01a (after ~45seconds).

Looking for advice on next steps. Connects to the audio system, not finding any tsb related.

 

Welcome to the forum
The battery charged voltage if that is stabilized has me wanting to retest.
Your alternator voltage is not a correct way to post its charging rate, but that's fine I understand the old school way of accessing a charging system. Your alternator charging rate is controlled and monitored via the ECU. So your will can measure voltage charging rates change constantly in seconds as the engine is running as various electrical system and components use power.
Electrical issues such as you are describing generally don't just happen without warning. However, my best suggestion is to have a shop do a basic diagnosis which they should find the issue at least... within an hour with few exceptions. Then you can decide to DIY or have it professional serviced?
I will say that your sitting voltage draw @+ 30 minutes if good but how long did it remain? seconds, minutes constant?
The #15 fuse I am sure you saw runs an accessory outlet so unless you have something plugged in you should not have the draw as you measured. So, I suggest the first thing is double check there is nothing plug into it. Then if not leave that fuse out as it does not appear from a casual glance support vital components If your battery voltage remains stabilized at 12.6+ then you need to start the long process of determine why that circuit powered by #15 fuse is causing a ghost draw.
However, I still advise you to let a competent shop in Automotive electrical diagnosis find the problem for you.

Disclaimer: Naturally my responses is really more or less guessing because most electrical system with a current draw really require the physical presents of the vehicle to do a few basic tests not covered completely in my response.

 

Edit: thinking you misread my original maybe. Fuse is #10, 15a fuse.

thanks for the reply. Per this wiring diagram I’m only seeing audio system, which aux plug are you referring to? Other than a USB Plug in for her phone, she shouldn’t have anything.

 

Yes I did.
The info I referred was for fuse 15. So the Aux port/connector does not apply.
Fuse #10
Depending on the sound system? Is it Bose or other?

 

Bose system.

 

Bose system integrates a few power systems that is controlled and viewed by the heads-up supply.
I wish I could help more but it was a challenge for me and other professionals when converted my BOSE sound system to separate and use none Bose amplifiers and speaker and audio input from the Mazda head unit and still maintain the heads-up control feature. We ran into all sorts of challenges having to re- distributed power systems. It took about 2 months working with a Bose Tech support, the actual engineers at Rockford Fosgate and Audio Control to build the and adapt to Mazda sound system.
If your power drain has to do with your BOSE sound system integration it the heads-up display and security system you will either get very lucky and find your parasitic drain or you may need to find a Auto stereo shop that is very experienced with factory BOSE system or a dedicated Auto Electric Service shop?

 

edit: confirmed the Bose system stops after pulling the fuse. Again, the whole entertainment screen gets wiped as well.

Running the car without the fuse in = no main entertainment screen. I still hear beeps from the proximity sensors when backing up though. Are we sure it’s tied to the whole Bose system?

 

I did not say all of them.
When you pulled the fuse you confirmed the voltage drain stopped?

 

Testing currently. Battery was on a tender last night and I have pulled the fuse this morning. Will check voltage every few hours

 

Unfortunately, Mazda claims they were unable to replicate. They had it for 5-6 days. Car hasn’t given us issues in since. The only thing that we were guilty of was leaving the fob in the car when in the garage. Although, during testing I did remove it.



My only thought is that my original battery was actually bad and the weak battery was unable to fully put things to sleep? (I’m having to convince myself of this).