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Discussion Starter · #1 ·
With no warning symptoms my 2014 was totally dead Sunday morning, after last driving it the previous Friday. No indicator lights, no ticks, horn, trunk release, nothing. When I put a charger on, it seemed to show a fully dead battery, so I assumed it had succumbed to the Texas heat. But I left the charger on just to see what would happen, and about an hour or two later the charge indicator came on. After 12 hours charging, the car is now running fine. (But info, radio presets, even automatic windows had to be reset.) After a little bit of driving there's no hint that the battery was ever low.

I think I may have used the dome light on Saturday, but it's hard to imagine that if I forgot to turn it off it would so totally drain a battery overnight, right?

It's a MT with 22K. My concern is what caused the sudden drain -- and whether it'll happen again. And something makes me wonder whether it was actually some sort of computer issue, and the battery was never really drained (but was reset by the charger somehow). Is this possible? The charger has just an idiot light that's supposed to gradually change from yellow to green -- but to me it always looked just yellowish-green, so I couldn't tell what was actually happening. During the first hour on the charger, that light was not on at all -- only the red power light, which, I believe, indicated no charging. I did not try to start the car until it had been on the charger overnight.

Ring a bell with anyone?
 

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All I can say is drive it till it happens again. If it doesn't happen with a week then something drained the battery. If it happens again I would get the battery checked. Don't know where you live but here in Thailand the battery is only under warranty for 1 year. The heat really kills batteries. Had to replace mine after 2 years and only had 15,000km on the car.
 

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Discussion Starter · #4 ·
Ok, thanks. No sign yet of a weak battery. I'd never thought a battery could seem so completely dead and then be brought back to full health. Maybe does the Mazda somehow turn off the entire electrical system when the battery has discharged past a certain point? Weird.
 

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I had read on this forum that a Garmin portable GPS unit would not use enough current to kill the battery so I left mine plugged into the 12 volt outlet. I went out one morning and my battery was so dead that the door wouldn't even unlock except manually by key. Nothing would work. My new car was only about 3 months old. I charged it for about 6 hours and haven't had any problem since. Of course I didn't leave the GPS plugged up again.
 

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Some newer cars have a battery protection program, programmed so that at a certain point it will shut down all systems, allowing just enough juice to start the car. However, I do not know anything about Mazda's system.
 

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Discussion Starter · #7 ·
I had read on this forum that a Garmin portable GPS unit would not use enough current to kill the battery so I left mine plugged into the 12 volt outlet. I went out one morning and my battery was so dead that the door wouldn't even unlock except manually by key. Nothing would work. My new car was only about 3 months old. I charged it for about 6 hours and haven't had any problem since. Of course I didn't leave the GPS plugged up again.
Yeah, that doesn't seem right. I'll bet @Road Trip is on to something re the whole system shutting down at a certain point. My worst-case scenario was (possibly) a dome light left on for less than 24 hours. And that leads to a battery so dead it can't even power an indicator light?

But I would have thought our experiences would have been a lot more common around here if Mazda had intended for there to be a shutdown response. So, I'm still confused, but I'll be awfully carefully with the dome lights from now on.
 

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After I signed the papers for my 2015 which was on showroom floor display, a salesman got in to drive it to the garage for prep and found the battery was dead. They looked around for a problem and found the little dome light inside had been turned on by some looker and no one noticed. The sales manager said, "This is embarrassing." It happens.
 

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After I signed the papers for my 2015 which was on showroom floor display, a salesman got in to drive it to the garage for prep and found the battery was dead. They looked around for a problem and found the little dome light inside had been turned on by some looker and no one noticed. The sales manager said, "This is embarrassing." It happens.
This. I see it all the time in the showrooms. Last year parked a car, and let a little one sit in the front seat. Tried to start a car next day but just the dash lights came on, the brake paddle was super stiff and car would not start. Immediately looked at the dome lights to discover that one of them was pressed on. I found out hard way that there is no battery protection when the dome light is pressed on.
 

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I have a 2016 sp25 and found this morning my headlights had turned on over night. They are always in "auto" and when I locked the car they were off. Had to jump start the car and it recharged OK but I'm not going to use the auto system again
 
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