Reason for flat ND battery

  1. My model of MX-5 is: ND
  2. I’m based near: Hereford
  3. I’m looking for technical help or recommendations on: Battery issue

Hi guys, recently picked up a 2018 2.0. I daily drive it for work, and coming from an RX-8, I was hoping for some solid Mazda 4-cylinder reliability, eheh. Well I went to drive home from work a few days ago, and… nothing! Start-stop button didn’t work (didn’t even light up), central locking dead, yada yada. Phonecall and slightly mad girlfriend later, checked the battery and it was at 3 volts, oh dear. Jump started it (with her Mazda 3, of course :grin: ) and all seemed well.

Upon further reflection that night, I think I might have inadvertently left it in ACC ignition mode for 4 or 5 hours with the heated seats and blowers on - I parked up with roof down, and put it back up after 10 mins or so. Engine was off, so I pushed the start button twice to get the windows back up, and then I guess must have walked off like an idiot. I’m sure I remember locking it, though…

Anyway, I just wanted some closure really - is there really no timeout or anything on the ACC mode, and is this the likely reason I had a flat battery, do ya think?

Ta, Joe

If you have the Mk4 RF, this could be the known problem…

The 2017 RF suffered from flat battery from leaving your cruise control on i:e the display in the dash but it would take a long time for the battery to go flat only showed up on cars that was weekend toys I know I had one …that was a soft ware fix …but if you left the ING on and tryed to lock it my would not lock and sounded a warning bleep as it would if you left your keys in the car and try to lock it so unless you left your car unlocked cannot see it being that but the ND DO SEEM TO Suffer a lot more problems than the other models for such a young car so much so I gave up on mine sold it back TO THEM and brought a NC

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Ah yes I’ve read about the RF battery issues - I have a softtop, forgot to mention. By ACC I mean accessory mode, could be calling it the wrong thing, but whatever it’s called after pressing the start button twice without starting the engine. Thanks though.

HI Joe. Yes, I have walked off and left the ignition in the same position as you on my soft top ND shortly after I first had it, and even more absent mindedly I also forgot to connect the smart charger, net result, flat battery. However if I do things correctly no problems, and it’s now just over 5 years old. So don’t worry too much, it’s not something going wrong it’s just caused by the design of the system. Also it’s worth remembering that every time you start the car you need to drive around 6 - 8 miles to replace the energy used by the battery, so if you’re doing short journeys be careful. Get a “smart” charger if you haven’t already got one! Good luck!

ACC switches off after 25 minutes.

Although there is obviously some dark current in the OFF position, I have left my car (2017 soft top) parked for up to 3-4 weeks and it has still restarted normally so I don’t think it’s excessive. Short journeys with everything on? HRW and heated seats will be the biggest ‘normal’ drain.

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