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flat battery

35091 Views 78 Replies 21 Participants Last post by  DONDERA
hello guy!
proud CX-30 FWD owner here in Europe, love this car and Mazda generally, coming after 4 years with Mazda 3 (y)

I got this car 3 months ago, a few days back, being at work and having the car close to me, because at times I needed stuff from inside, I decided to keep it unlocked with the keys inside and this was for 12 hrs.

I finished my duty and when I was about to go ... boom, no power whatsoever :confused:

the car service arrived quickly and helped me to start the car, all good then, they checked the alternator and seem to be OK as well but what may have happened?

I suspect the in-car lights might have been on but still, I couldn`t expect the battery to drain that much, the ext lights were surely off so, did anyone encountered such issue?

Dan
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as far as I know, the interior lights switch off after a few minutes, even when the keys are inside (if all doors are closed shut).

I would take it up with Gasan, your official Mazda dealer (I'm a fellow Maltese) as it's definitely something with the said battery or else, the whole key/radar interior system which detects the keys inside (in order not to let you accidentally lock the said keys)
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Hi Dan, It does seem like it was a dead battery, but you can never be too careful with going to a dealer and getting it checked out.
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an update ...
long story short, faulty main battery :confused:

the first check-up revealed nothing faulty as the "engine malfunction" message that I`ve had after the second battery failure has disappeared and the technician cloud have not identified any fault, probably did not properly check the battery as I have suggested them ... then a third flat battery occurred, I started the car with a power bank, the same error appeared and I went straight away to the dealer. This time they said that the hybrid battery is faulty and needs to be ordered and to use the car without keeping it unlocked :unsure: but ... after several minutes waiting to get the car back, they returned saying that the car refuses to start even with the help of the power bank lol ... I said ... guys, just give me a backup car and let me go to work eh ..

Next day miracle, they called back saying that the main battery was faulty this time, they replaced it and ... it looks ok now, I can keep my car unlocked with or without the fob inside.

I am still concerned, guess I will check again by keeping it unlocked for longer although I am forced to drive almost every day.

You may try this as well and let us / me know how it goes.

thanks for your insights :)
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Hi Dan,

I've had similar problems in that my battery has died after the alarm has gone off for no apparent reason. This has happened on 3 occasions and my car is now back at the garage for a second time. They have already fitted a new battery but again the alarm went off and the car was completely dead. I couldn't open the door or put the alarm off using the key. It goes off after 10 long repeats. On one occasion the alarm went off even though the battery was apparently dead! It is certainly loud enough. I was given a replacement mazda 3 and even though I hadn't driven it the alarm went off at 7.30 in the morning. Am I doing something wrong? The keys are kept in the house and the car in the drive. I have had a mazda 121, 323, 626, 5 and Cx3 without any problems. Any ideas please?
Hi Dan,

I've had similar problems in that my battery has died after the alarm has gone off for no apparent reason. This has happened on 3 occasions and my car is now back at the garage for a second time. They have already fitted a new battery but again the alarm went off and the car was completely dead. I couldn't open the door or put the alarm off using the key. It goes off after 10 long repeats. On one occasion the alarm went off even though the battery was apparently dead! It is certainly loud enough. I was given a replacement mazda 3 and even though I hadn't driven it the alarm went off at 7.30 in the morning. Am I doing something wrong? The keys are kept in the house and the car in the drive. I have had a mazda 121, 323, 626, 5 and Cx3 without any problems. Any ideas please?
I, too, had a dead battery issue and was told that Mazda was aware of the problem and thought it was caused by the car searching for something. I may have left it unlocked but the fob was well away. My audio had already crashed so it may have been on an endless search for Pandora.

My metal key didn't work because it had never been cut for the car. Mazda sent a code and the dealer cut it.

A "Global System Reboot" had me back on the road and so far/so good. I do make sure it's locked.
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I, too, had a dead battery issue and was told that Mazda was aware of the problem and thought it was caused by the car searching for something. I may have left it unlocked but the fob was well away. My audio had already crashed so it may have been on an endless search for Pandora.

My metal key didn't work because it had never been cut for the car. Mazda sent a code and the dealer cut it.

A "Global System Reboot" had me back on the road and so far/so good. I do make sure it's locked.
Thanks for that.

I was wondering if there was any way a mobile phone could interfere with the computer and affect the battery. I have my phone connected by Bluetooth to the car and also have android auto. Could they possibly be the problem?
Hi Dan,

I've had similar problems in that my battery has died after the alarm has gone off for no apparent reason. This has happened on 3 occasions and my car is now back at the garage for a second time. They have already fitted a new battery but again the alarm went off and the car was completely dead. I couldn't open the door or put the alarm off using the key. It goes off after 10 long repeats. On one occasion the alarm went off even though the battery was apparently dead! It is certainly loud enough. I was given a replacement mazda 3 and even though I hadn't driven it the alarm went off at 7.30 in the morning. Am I doing something wrong? The keys are kept in the house and the car in the drive. I have had a mazda 121, 323, 626, 5 and Cx3 without any problems. Any ideas please?
I am pretty sure that a brand new battery would never have such drain issues in a matter of hours be it from "seeking of communicating with the fob", alarm or anything else, to me it looks like a battery fault. In my case, it died 3 times when actually should have not happened, with the fob inside or away, with the car locked or not, this massive drain should have not happened.
Since it has been replaced, I left the car unlocked for several times, with the fob inside or away, no drain occurred, fingers crossed and as a precaution, I purchased a powerbank gadget :sneaky:
I don`t have an alarm although I wish to, for now, the way I use the car, isn`t a must.
I am pretty sure that a brand new battery would never have such drain issues in a matter of hours be it from "seeking of communicating with the fob", alarm or anything else, to me it looks like a battery fault. In my case, it died 3 times when actually should have not happened, with the fob inside or away, with the car locked or not, this massive drain should have not happened.
Since it has been replaced, I left the car unlocked for several times, with the fob inside or away, no drain occurred, fingers crossed and as a precaution, I purchased a powerbank gadget :sneaky:
I don`t have an alarm although I wish to, for now, the way I use the car, isn`t a must.

My new battery died 2 weeks after having been installed. The alarm went off and all electrics failed again. Had to use the manual key to open door. That's hard enough! Currently waiting to get the car back again. I hope your problem is solved.
My new battery died 2 weeks after having been installed. The alarm went off and all electrics failed again. Had to use the manual key to open door. That's hard enough! Currently waiting to get the car back again. I hope your problem is solved.
Did you get that "engine malfunction" error message on the dashboard? I remember the technicians weren`t able to identify the issue without that error, or at least this is what they said ... I also remember that one of them said that a sign of faulty battery or battery low charging is the i-stop not kicking in, it used to do that on me. However, I didn`t consider it an issue thinking that it needs a little time to work, well now the i-stop is functional after a few minutes of driving; previously it used to not work even after 20 min.
Thanks for that.

I was wondering if there was any way a mobile phone could interfere with the computer and affect the battery. I have my phone connected by Bluetooth to the car and also have android auto. Could they possibly be the problem?
I am suspicious; compounded by the fact that my phone is a Huawei and Android Auto won't work on it. (US) My audio crashed first; stuck on Pandora but no sound. My Sirius trial had just expired so I thought maybe a glitch had occurred. I had started the car, it was looking for Pandora but when I looked at my phone I noticed the battery was low so I plugged it into the USB. Apparently this is a no-no as it doesn't know where to connect to Pandora so I suspect this was a contributing factor.

The next morning is when I found the battery dead. After the Reboot, Pandora works well but I haven't tried to charge the phone in the car yet . . . Has anyone else had any problem charging their phone via the USB?
I am suspicious; compounded by the fact that my phone is a Huawei and Android Auto won't work on it. (US) My audio crashed first; stuck on Pandora but no sound. My Sirius trial had just expired so I thought maybe a glitch had occurred. I had started the car, it was looking for Pandora but when I looked at my phone I noticed the battery was low so I plugged it into the USB. Apparently this is a no-no as it doesn't know where to connect to Pandora so I suspect this was a contributing factor.

The next morning is when I found the battery dead. After the Reboot, Pandora works well but I haven't tried to charge the phone in the car yet . . . Has anyone else had any problem charging their phone via the USB?

My phone is a Huawei p30 Pro and works fine with android auto.
My phone is a Huawei p30 Pro and works fine with android auto.
Yes, I understand it's a US issue. I should have been more clear.

Apparently the 5G concerns have been addressed somewhat so maybe there's hope.
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Did you get that "engine malfunction" error message on the dashboard? I remember the technicians weren`t able to identify the issue without that error, or at least this is what they said ... I also remember that one of them said that a sign of faulty battery or battery low charging is the i-stop not kicking in, it used to do that on me. However, I didn`t consider it an issue thinking that it needs a little time to work, well now the i-stop is functional after a few minutes of driving; previously it used to not work even after 20 min.

The first time I got about half a dozen warnings before the engine died in the drive. Every other time I couldn't get into the car without using the manual key and nothing came up on the screen. The fob didn't work when put on the start button. Luckily it only ever failed to start in my drive. I always leave the car in gear when parking.
The first time I got about half a dozen warnings before the engine died in the drive. Every other time I couldn't get into the car without using the manual key and nothing came up on the screen. The fob didn't work when put on the start button. Luckily it only ever failed to start in my drive. I always leave the car in gear when parking.
No problem with the istop.
I too have a persistent battery problem.
Day after delivery in March, I couldn't unlock the vehicle using the fob or drivers door handle. Had to use the manual key.
Attempted to start the engine and nothing, except a few instrument cluster lights flashed randomly when I pushed the starter button.
DC volt meter on the battery showed 7vDC.
Mazda response called out who jump started the vehicle. No issues found that would have depleted the battery in a day, no cabin lights left on, all doors secured.

I left the battery on a 24 hour charge using a battery conditioner.

No issues since, till last week when three days after using the vehicle on a long journey, I couldn't again get access using the door handle nor key fob. Absolutely everything was dead and having used the manual key to gain entry, the dash was completely dark.
DC volt meter on the batter showed +2.4vDC. That's three days after using the vehicle. No heated seats, no lights, just lots of mileage, mostly at speed.
Mazda response called again. Jump started the vehicle and again, nothing found to cause the issue.

The car's booked in now to the supplying Dealer.
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I too have a persistent battery problem.
Day after delivery in March, I couldn't unlock the vehicle using the fob or drivers door handle. Had to use the manual key.
Attempted to start the engine and nothing, except a few instrument cluster lights flashed randomly when I pushed the starter button.
DC volt meter on the battery showed 7vDC.
Mazda response called out who jump started the vehicle. No issues found that would have depleted the battery in a day, no cabin lights left on, all doors secured.

I left the battery on a 24 hour charge using a battery conditioner.

No issues since, till last week when three days after using the vehicle on a long journey, I couldn't again get access using the door handle nor key fob. Absolutely everything was dead and having used the manual key to gain entry, the dash was completely dark.
DC volt meter on the batter showed +2.4vDC. That's three days after using the vehicle. No heated seats, no lights, just lots of mileage, mostly at speed.
Mazda response called again. Jump started the vehicle and again, nothing found to cause the issue.

The car's booked in now to the supplying Dealer.
Sounds very similar to my problems. I couldn't find anything left on and checked to make sure everything was off. I followed Mazda's advice on keeping the car running during lock down. It all seemed fine until the alarm went off again. Currently on my 2nd battery waiting to see what happens next. I'm still waiting to get mine back from the garage. Good luck!
Does anyone else find their battery is dead after the alarm goes off?
That's odd Paul... I'm too planing a 2k miles across Europe this summer, guess if anything happens, I'll... 🤔 I have a powerbank thing for just in case, weird how these battery failures happens
It appears that the issue with batteries and alarms are not just reserved for the Cx30. Apparently the 3 cx3 6 and cx5 have all had similar problems.
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