Good afternoon,

So when I bought the car 2 months ago at 112k miles the battery was low and the terminals corroded. We removed the battery and cleaned it and it seemed fine. The battery was last replaced at 72k miles 3 years ago. Recently I started it up and it seemed a bit slow and took it to my mechanic for some other repairs and had him check it and he said the CCA (cold crank amps) were low and I needed a new battery. I picked up the car and it started fine but I called the Auto Club to test it and they told me the idle voltage was low and most likely the car needed a new alternator (results below). I bought a new battery since it was suspect at 3 yrs old and the mechanic tested the charging voltage with and without load and was getting inconsistent results. He told me it was reading okay at idle but under load with A/C and lights it was reading 12 something so charging not normal. Sorry I don't have specifics. It took it to Autozone to double check and they said the alternator failed their test. Anyway I'm going to have the mechanic replace it and alternators aren't cheap at $350 so hopefully this will fix it. Thanks for reading my story and any input would be much appreciated. The previous owner had the car serviced mostly at a dealership so I'm surprised I inherited this problem but stuff happens. Maybe the slow cranking battery was a warning sign the day I bought it but I just figured it had been sitting around not being driven. I had the car inspected but not sure if he checked the charging system or not.


Service Call:
Date: 6/18/2025
ID: 561808

Test Data:
Overall Result: GOOD & PASS
The battery has useful life remaining.
State of Health: 85%
State of Charge: 100%
Voltage: 12.81 V

Battery Details:
Type: FLOODED
Set Capacity: 600 CCA/SAE
Measure Capacity: 512 CCA/SAE

System Details:
Starter Voltage: NORMAL / 10.44 V
Idle Voltage: LOW / 13.24 V
Idle (with load) Voltage: NORMAL / 13.64 V
Diode Ripple: NORMAL / 0.33 V

 

my car is a 2016 cx5 grand touring AWD.

 

Looks pretty good to me. The drop in CCA is expected but well within acceptable range for an engine that size. Might pay to check earth connections.

 

So I was ready to have mechanic install a new alternator and decided to take it to another shop for a second opinion. Glad I did....they tested it and said the car was fine. I was very impressed with the shop and the service writer was very familiar with Mazda's. Shop is located in Fullerton, CA and I plan to go there in the future. Many shops I have spoken to didn't seem familiar with Mazda's...I'm hoping that's a sign they don't break down much.

 

Good to hear. Sounds like they know the correct procedure for testing SMART chaging systems. I have seen very experienced mechanics replacing alternators then say the new one is no better.

 

You should name the shop. Any service shop that does good work should be promoted.

It not a Mazda thing it is lack of Diagnostic Training . To many old school mechanic that think they know how to work on any vehicle . Sadly makes the auto service industry as a whole look unprofessional.
Thats why in the shop I manage if we can’t find your problem in an hour you don’t pay us. And my techs don’t get paid either. lol. This year all my techs earned their money.

 

Fisk Automotive in Fullerton, CA Joel helped me. And thanks to all of you especially Charlescrown for the info on SMART alternators. I had done a lot of research on this issue and didn't read or hear anything about SMART type alternator systems until now. Now I know why the voltage readings varied and were hard to interpret. The Mazda is running good now!

 

Yea when they first came out (long time ago now) many got replaced because tech's didn't know what readings to get and were going off the old 14.5 volts. I have put many alternators on a test bench and yes it takes quiet a bit of power to drive them at full output so yes there is probably a fuel saving and power gain under certain driving conditions so it's understandable why most manufacturers use them.

 

https://www.fiskauto.com


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