Battery/Alternator trouble?

floridavet

Member
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Mazda CX-5
Just curious if anyone more knowledgeable than me has any ideas on what is wrong with my CX5. I live in a smaller town so most the mechanics are closed for the weekend but I'm going to take it in Monday.

Background history I replaced my battery in January 2017.
Car has been great it is a Cx5 (2015) with 50k miles. Yesterday my wife goes to start it after work and the electronics turn on inside but it won't start. One of her coworkers pushes in the fuses in the cabin (which I don't think made a difference) but the car then started and she drove home. This morning I get in and it starts. I make a short 5 minute drive to the store, pick up some things, and drive back no problem. About an hour later I go to get back in the car and it won't start (but all the electronics inside work). Hmmm. I jump start it and it works fine. Drive it around for 30 minutes and stop at Advance Autoparts to see if the battery is bad and needs to be replaced. It tests good. They even take it out, charge it all the way up, test it again and it tests fine.

They put the battery back in and I notice the power locks aren't working (they won't unlock the car but will lock it and that is true of the interior ones and the key fob). I drive it the 15 minutes home and then turn it off. I try the power locks one more time and hit unlock and they automatically click back and forth a few times and then work. The fob works now as well. I tried starting the car again after turning it off and it worked. We will see if it starts up when I try to go out in a few hours.

The guy at AA said it is probably the alternator. Does that sound right? Thanks.
 
An easy way to check if the alternator is charging the battery is to hook up a multimeter/voltmeter to the battery posts while the car is running, you should be getting a voltage reading of around 14 volts.
 
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Don't have an answer to your problem but I wouldn't suspect a bad alternator.Auto parts store employees aren't noted for giving accurate advice.What you don't want to do is unjustly condemn a good factory OEM alternator (or any original factory part) and replace it with a chain store/aftermarket one that won't last.Aftermarket auto parts quality is a real crapshoot these days. Jmaz
 
If you have power outlet nearby, do yourself a favor and buy smart battery charger /maintainer, particularly if you're short tripping it like that. Hook it up, on car, whenever is possible, and leave it for as long as you can. Any battery stays way more happy if it is charged fully. Some smart chargers can achieve just that.
 
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Why was the battery replaced to begin with? Are the battery cable clamps in good shape, like no corrosion or anything, and are they tight enough? I agree with Jmaz about the alternator diagnosis, or lack of.
 
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Just curious if anyone more knowledgeable than me has any ideas on what is wrong with my CX5. I live in a smaller town so most the mechanics are closed for the weekend but I'm going to take it in Monday.

Background history I replaced my battery in January 2017.
Car has been great it is a Cx5 (2015) with 50k miles. Yesterday my wife goes to start it after work and the electronics turn on inside but it won't start. One of her coworkers pushes in the fuses in the cabin (which I don't think made a difference) but the car then started and she drove home. This morning I get in and it starts. I make a short 5 minute drive to the store, pick up some things, and drive back no problem. About an hour later I go to get back in the car and it won't start (but all the electronics inside work). Hmmm. I jump start it and it works fine. Drive it around for 30 minutes and stop at Advance Autoparts to see if the battery is bad and needs to be replaced. It tests good. They even take it out, charge it all the way up, test it again and it tests fine.

They put the battery back in and I notice the power locks aren't working (they won't unlock the car but will lock it and that is true of the interior ones and the key fob). I drive it the 15 minutes home and then turn it off. I try the power locks one more time and hit unlock and they automatically click back and forth a few times and then work. The fob works now as well. I tried starting the car again after turning it off and it worked. We will see if it starts up when I try to go out in a few hours.

The guy at AA said it is probably the alternator. Does that sound right? Thanks.

There are 2 switches or interlocks that must be pressed in order for the car to start as normal.

1 is the BRAKE PEDAL SWITCH.
2 is the PARK/NEUTRAL interlock.

If either of these switches are failing or failed the car will turn on but will not start.

for #1 you can verify that the brake pedal is being depressed firmly.
for #2 you can verify that the gear lever is in the P or N position.
 
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To OP, do you have push-button engine start? And when you said the engine wont start did the engine crank at all? If the engine didnt crank at all I believe one of the switches mentioned by mazdadude above or push-button or key ignition switch may have intermittent bad connection. Theres a TSB on bad transmission interlock switch which makes your engine wont crank but Im not sure if that applies to your 2015 CX-5. With only 50K miles alternator and starter usually are not the suspect of the problem.
 
If it is working now it could have been loose or poorly connected battery cables that was fixed by removing and reconnecting the battery. If you drive the car regularly for 20 miles are so you should not need a battery charger/tender.
 
Why was the battery replaced to begin with? Are the battery cable clamps in good shape, like no corrosion or anything, and are they tight enough? I agree with Jmaz about the alternator diagnosis, or lack of.


The car wouldn't turn on and the battery registered as dead. Jump started it and drove it to get the battery replaced. It was 3 years of ownership in Florida and another 1.5 in Iowa.

Yesterday I cleaned the terminals and put the clamps back on and tightened them. Hoping that will fix the problem.
 
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To OP, do you have push-button engine start? And when you said the engine won’t start did the engine crank at all? If the engine didn’t crank at all I believe one of the switches mentioned by mazdadude above or push-button or key ignition switch may have intermittent bad connection. There’s a TSB on bad transmission interlock switch which makes your engine won’t crank but I’m not sure if that applies to your 2015 CX-5. With only 50K miles alternator and starter usually are not the suspect of the problem.


Yes it is a push start. Your thoughts might explain why it didn't originally start for my wife and then did. Thanks for the advice.
 
Well it is at the shop now (wouldn't start again this morning) so we shall see! Will update in case anyone else has this problem.
 
Having a similar issue. Wife drove CX5 all day and at her last stop it would not start. Lights nice and bright. Jumped it and we went to dinner a minute away. I figured I would have to jump it again but it started right up. Drove it 40 miles, stopped and started driving an additional 15 miles with no issues.
 
Having a similar issue. Wife drove CX5 all day and at her last stop it would not start. Lights nice and bright. Jumped it and we went to dinner a minute away. I figured I would have to jump it again but it started right up. Drove it 40 miles, stopped and started driving an additional 15 miles with no issues.

Decided to change the battery today, lost my free SAT that I had for 3 years! Had to subscribe to get it back. All good now.
 
Ok I promised an update and finally have it.


So I took it to the shop and after 2 hours they decided that we had left a cabin light on and that was draining the battery. I thought it odd because we were in the car for multiple days and I swear we looked at the lights and didn't notice them on. Even drove it at night and you'd think we'd notice it. But I thought I've done stupid things before why not this time? We took it home and the car worked fine for two weeks.

Then this Tuesday bam wife goes to start it when leaving work and it won't start again. She gets a jump and lets me know with some colorful words that the lights are not on when I ask. So I drove the car to the dealership to have them look at it since I needed a recall done anyway. They tell me the battery failed their test. So I bring the battery back to Advance Auto Parts. They say it tests fine so I can't replace it under warranty.

So here is the kicker. When I replaced my battery last year I just went in to Advance Auto Parts. They looked up my model, gave me some options, I picked one on the cheaper end, they installed it and I left. The fishy thing was the battery I picked wasn't the same dimensions and they told me they couldn't put the battery box on it because of that. I don't know much about cars so I took the "professionals" word for it. Now when I go in today the guy says he thinks my problem is the cold crank amps on this battery is only 540 and the cold crank amps on the OEM battery was 640, on top of that without the battery box there is no insulation on the battery. I live in Iowa, it gets cold. Now things are all making a bit more sense, the car always started when in the garage but all the times it wouldn't it was outside and cold. The last two weeks we had a bit of a heat wave for December and then it started to get cold again. So armed with more knowledge I bought a Group 35 battery (instead of the 26R that was in it) elsewhere and so far it is running fine. Hopefully that was the problem. It ended up costing me 200 bucks for the battery and that initial visit to the mechanic and I consider that a tax on me not doing my own research before trusting them to help me pick out a battery. I asked them why would the 26R even be a choice if it isn't up to standards and doesn't fit in the factory space? Who knows. Expensive lesson learned and hopefully this solves the problem.
 
There is a bit of luck getting a good battery but in Iowa you probably need the 35/640 amps or more...
 
Ok I promised an update and finally have it.


So I took it to the shop and after 2 hours they decided that we had left a cabin light on and that was draining the battery. I thought it odd because we were in the car for multiple days and I swear we looked at the lights and didn't notice them on. Even drove it at night and you'd think we'd notice it. But I thought I've done stupid things before why not this time? We took it home and the car worked fine for two weeks.

Then this Tuesday bam wife goes to start it when leaving work and it won't start again. She gets a jump and lets me know with some colorful words that the lights are not on when I ask. So I drove the car to the dealership to have them look at it since I needed a recall done anyway. They tell me the battery failed their test. So I bring the battery back to Advance Auto Parts. They say it tests fine so I can't replace it under warranty.

So here is the kicker. When I replaced my battery last year I just went in to Advance Auto Parts. They looked up my model, gave me some options, I picked one on the cheaper end, they installed it and I left. The fishy thing was the battery I picked wasn't the same dimensions and they told me they couldn't put the battery box on it because of that. I don't know much about cars so I took the "professionals" word for it. Now when I go in today the guy says he thinks my problem is the cold crank amps on this battery is only 540 and the cold crank amps on the OEM battery was 640, on top of that without the battery box there is no insulation on the battery. I live in Iowa, it gets cold. Now things are all making a bit more sense, the car always started when in the garage but all the times it wouldn't it was outside and cold. The last two weeks we had a bit of a heat wave for December and then it started to get cold again. So armed with more knowledge I bought a Group 35 battery (instead of the 26R that was in it) elsewhere and so far it is running fine. Hopefully that was the problem. It ended up costing me 200 bucks for the battery and that initial visit to the mechanic and I consider that a tax on me not doing my own research before trusting them to help me pick out a battery. I asked them why would the 26R even be a choice if it isn't up to standards and doesn't fit in the factory space? Who knows. Expensive lesson learned and hopefully this solves the problem.

The thing about that battery insulation is that (for the most part) it's to protect the battery from underhood heat, not to keep the battery warm in the cold weather.

I see that you checked and cleaned the battery terminal connectors. What about the other ends of those cables? The ends that connect to the car? All of these connections should be cleaned with a wire brush and have some type of contact preservative applied.
 
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