2017 Mazda CX-5 105,000 miles. Battery is just over a year old.

Daily driver said the the crank time seemed longer than usual. No CEL, Battery light, or codes. I had her take it to autozone to do a load test on the battery.

They said battery was fine but the alternator was dying, passing less than 12v. They said it also failed the charging system test.

I’ve been checking the battery after resting over night (between 12.33 and 12.55 regularly). When on, the battery 13.5+.

Today I tested the alternator with a multimeter and it was at 12.5v~ idle and around 13.6v while running.

While operating the vehicle myself trying to see if I noticed any other symptoms, I noticed that it shifts pretty hard in lower gears. It was also kind of hesitating/stuttering when first accelerating after sitting at a red light.

When I turned the radio/air conditioning off. The hesitating/stuttering stopped completely, and the hard shifting was still there but much less noticeable.

Not sure if the shifting/stuttering is a related symptom at all, just sharing as much info as possible to maybe diagnose what’s going on?

Attempting to attach a video of a multimeter recording during startup. Edit- can’t attach it for some reason, even below 20mb.

 

It could be a combination of both.
You don't say how old your vehicle/battery are.
Without lights and accessories, a "normal" Mazda alternator output is 13.8 - 14.3 volts at idle.
Normal battery voltage is 12.6 volts when fully charged.
The OEM batteries in these vehicles only last 3-5 years.
I had to replace my battery in less than two years.

 

Sorry about that... 2017 CX-5, about 105k miles. And the battery is just over a year old.

 

If the shop tested correctly then it would appear that your alternator is the issue.
Though if it has not been working correctly, for any length of time, it will have likely impacted your battery life.

 

Your basic information is pointing to the bad starting to fail.
You should have gotten a printed report from the battery load test. not just the person saying your battery is good.
They offer the free service, but it is not necessarily performed by someone that truly knows or understands what and how to do a proper battery load test.
I also am wondering about the no DTC? there is more area's in the ECU to look at then just pending DTC's. Nothing was mentioned about the other areas?????
With exactly what you explained is happening there would be indicators in the ECU.
I am not saying AutoZone FREE testing is not good customer service, but it does take some training to use and understand how -to and also to look at the overall battery condition which includes the terminals.
Their conclusion that your alternator is at fault is more pointing to a bad battery then the alternator!
The age of when you purchased the battery is NOT in any way how old the actual battery is.
You should also check the battery terminals both at the battery then the ground connects and starter or alternator.

You can not use your method of testing the alternator output. it is controlled by the ECU and it is not as simple as checking OLD SCHOOL way of voltage out put

Bottom line I recommend before you start guessing at what to replace seek out a service shop and have them do a proper testing of your battery and charging system. May not be free but if you use a shop that employees and ASE (current) you will be getting it done correctly.

It would suck if you replaced the battery and alternator and it turns out to be your ECU! $$$$$

ASE

 

PLEASE DONT POST A PICTURE OF YOUR VOLT/OHM METER READINGS..... This is an OBDII ECU operating system, and a video proposed is a waste of your time and members trying to help you.


I will say you have some skills if it were a vehicles pre OBDI(one.... not OBDII) (1994 and older) vehicles.

 

What ended up being the problem? My 2017 Mazda cx5 is doing the same thing. I've had the alternator replaced, but didn't solve the problem.

QUOTE=TurboTime;226450]2017 Mazda CX-5 105,000 miles. Battery is just over a year old.

Daily driver said the the crank time seemed longer than usual. No CEL, Battery light, or codes. I had her take it to autozone to do a load test on the battery.

They said battery was fine but the alternator was dying, passing less than 12v. They said it also failed the charging system test.

I’ve been checking the battery after resting over night (between 12.33 and 12.55 regularly). When on, the battery 13.5+.

Today I tested the alternator with a multimeter and it was at 12.5v~ idle and around 13.6v while running.

While operating the vehicle myself trying to see if I noticed any other symptoms, I noticed that it shifts pretty hard in lower gears. It was also kind of hesitating/stuttering when first accelerating after sitting at a red light.

When I turned the radio/air conditioning off. The hesitating/stuttering stopped completely, and the hard shifting was still there but much less noticeable.

Not sure if the shifting/stuttering is a related symptom at all, just sharing as much info as possible to maybe diagnose what’s going on?

Attempting to attach a video of a multimeter recording during startup. Edit- can’t attach it for some reason, even below 20mb.[/QUOTE]

 

Ok well that was a slight challenge to answer you question!

So to start off with no 2 vehicles issues are exactly the same! basically to many variables that influence problems.

Nuff said if all members cant understand that well ...


What, when, and miles was the last service done and was it a DIY or a service shop?

Did you get or if not get your battery load tested !

After that have a service shop scan your ECU for all the important information in 3 main areas'. DTC(s) x 2 area's and I/m monitor info is what is needed.

Then we can go from there.


PLEASE DO NOT randomly replace any parts before they have been verified as the problem or in the case of the charging system components shown to be the problem. More often that not it will cause other unrelated issues adding to the first unresolved one making it more difficult to diagnose the issues that started the random parts replacement.

 

Completely different scenario, but your comment about randomly replacing parts hit a note with me. My central heat was acting stange last week, gas was lighting then would suddenly flicker and go out. Called an HVAC company - who had done well for me in the past. The tech looked at the unit, did some testing and called his boss to conference video what was going on. He said the gas valve OR control board was bad. As the unit is still under warranty, he went and picked up both parts and replaced them sequentially. Neither part resolved the issue so I was still without a functioning heater after a full day or work on the unit. The owner came the next day and started checking things. He found the draft inducer motor was bad (not sure why the other tech didn't test this part in the begining). It took a 3rd day as it was late in the day and they couldn't get the part in time. What should have been a very easy diagnosis and repair took 3 days.

 

Obviously, the title of "TECH" was for impression and not earned?