I changed out the factory Panasonic at the 5-1/2 mark because it was getting weak when starting in cold weather. It was November and winter was still ahead. I think the 5 year mark (approximately) is being proactive to avoid breakdowns.
2017 CX-5 Died on the Highway
- Thread starter clownshoes2
- Start date
I never wait 5 years, 36 months for me. Won't take the chance after couple times where battery just died at the worst time.
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- 2020 CX-5 GT AWD
My understanding is that once you start the engine, basically, you can ( don't do it!) disconnect the battery and the engine will run, forever. Forever equals the amount of fuel in you tank. If your car dies suddenly, my limited understanding tells me that your alternator stopped working at some point and you did not catch the red light indication right away. The alternator puts out AC while the battery and the car is using DC so there must be a rectifier in between otherwise it wouldn't work. It could have been the belt, maybe the rectifier portion of it, something along those parts. Battery wasn't getting the DC anymore. Kept driving until the battery drained and the engine died. In addition to the red warning light on the dashboard, I have a usb charger with a voltage display plugged in the cigarette lighter. You can see the live voltage put out by your electric system and spot any voltage drop before it becomes a serious problem.
My understanding is that although the alternator charges the battery, the battery is still needed to supply the voltage to excite the field coils in the alternator.
Jack Rabbit
Banned
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- 18 Mazda CX5 AW
Please note that this is based on pre-2008 models before all these new systems.
Have had both happen.
1. Like the OP's situation,
My vehicle just stopped completely during highway driving - had to drift to side of road - bad alternator hence dead battery. Replaced alternator.
2. Single digit temperatures. Battery dead, jump started vehicle to get to work. Vehicle drove to work on what must have been alternator power. Got to work, came back out 30 minutes later to run a work errand. Vehicle wouldn't start. Was dead battery. Replaced battery. Alternator lasted for many years.
Ime, once vehicle is running, alternator will continue to provide power to engine to create sparks and keep vehicle running.
With these newer vehicles however, perhaps there is safety mechanism built into vehicle to stop vehicle so that any
sensitive electronic systems
aren't damaged ??
Perhaps, the alternator could continue powering the vehicle but is shutdown by the ECU ?
This is most likely a question that only the mazda engineers can answer.
imo, OP should still watch for an intermittent failing alternator.
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clownshoes2
2017 CX-5 GT No Tech - 2023 CX-30 GT NA
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- CX-5
Well, the vehicle seems to be running ok. I asked if they checked the charging system (AVR) test and they said the alternator seems to be charging. We drove it home yesterday and it didn't stop, and it started ok this morning and my wife hasn't called to say the car is dead so, there is the possibility that it WAS just a bad battery.
clownshoes2
2017 CX-5 GT No Tech - 2023 CX-30 GT NA
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- CX-5
That's all I can do. They replaced the battery and checked that the system is charging (and it is). I can't ask them to do more than that if the alternator is intermittently going bad.
Yep, for me it's 4 years, and I get a battery rated higher in CCA than the original.
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- '17 CX-5 Select
Once running, a normally operating alternator will generate all the power needed to run the vehicle, and provide it's own excitation. It's not a perpetual motion quandary, as the engine is providing the energy, burning gasoline, to spin the alternator rotor.
The issue is that the alternator output has lots of ripple, which modern electronics don't tolerate well. Injectors, ignition coils, pumps and solenoids have relatively large current demands and generate lots of current transients on the 12v power buss. The battery performs critical smoothing of this ripple, and does so until its internal resistance gets too high, typically correlative with hours in service, number of deep discharge/charge cycles, extreme cold & heat, etc. When the internal resistance, or post connection resistance gets too high, the ripple can be large enough to cause module or sensor malfunction, and subsequent drivability and stall issues. The tired battery may have enough reserve to start the car, but the electronics may not be happy when the vehicle is running.
Further, many modern charging systems depend on a good battery to supply ALL the vehicle power needs for short periods, reducing charging current and engine load, both to manage the battery service life better and for fuel savings. The PCM lowers the charging current, where the net current flow is from the battery reserve.
In cases like the OP, it may not have been the battery itself, but the post connections that haven't been disturbed in 5 yrs and have 5 yrs of battery acid fume exposure. Those connections, of course , are disturbed and usually improved when one installs the new battery.
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
VERY well said AVC!
I have been getting my batteries at Walmart since they would die within the warranty timeframe and I’d get some discount on the replacement due to the pro-rating of the old battery. The last time I had to get a new battery, the warranty was down to two years so I said I’d just bring it in before the two year mark and get a new one. But I forgot to do it and the battery lasted over 4 years. When I went to replace it, Walmart was checking to make sure the battery that you were turning in was actually dead. My clever plans foiled again!
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