Merry Xmas everyone, I've managed to piss off most of my neighbours over Xmas seeing as my alarm has been going off whenever it felt like it and no one bothered to tell me. I found out today and now found my car is dead, no power in the battery, last time i drove the car (a week ago) the car didn't want to unlock on the keyfob until i moved the fob close to the window. The battery is current indoors on charge so will check if the alternator is working later, could it simply be a knackered battery ? one chap did say that no lights were flashing, my car was simply making loud beeps ?
Car alarm going off then dead battery.
- Thread starter tuco
- Start date
The absence of flashing indicator lights when alarm triggered may be because that function has been coded out just leaving the siren operating when alarm is triggered. Did the indicators ever flash when the alarm was triggered in the past?
If they worked before it could be its down to the low battery, maybe gone into transport mode, when you refit the battery fully charged check to see if the A/Con has all the fan speeds working, if they dont work then suspect it will have put itself into transport mode. If thats the case there was a recent post about resetting that using BMW Scanner 1.4. INPA will also reset it to normal if you have that software.
Probably fecked then.tuco said:
Battery back in car and volts dropped to 10.1V when car was started, then rose to 14.50V whilst idling(alternator working). Reading 12.68V when i turned the car off, I'll check the voltage again in a bit to see if it has dropped, car is used once a week at best (35 miles round trip for food) and the only thing i can think off that might drain the battery is the Pure DAB i fitted earlier this year (powered off the cig socket, left plugged in) The fact the battery dropped low enough that i couldn't unlock the car or get any lights to show on the dash does concern me though (battery damage ?) that i might just get a new one https://www.tayna.co.uk/car-batteries/bosch/s5a08/ sensible ?
tuco said:
I had very similar on my 3 series the week before Xmas, mine was reading 10.1V via the secret menu so I replaced the battery and all been good since
Can’t do it and disservice, was the original 2006 battery
OP, I recently experienced exactly what you have described and also due to alarm issues. My battery was completely dead, no dash lights, radio, key fob activity, nothing. Recharged it, disconnected the bonnet sensor as I believe that’s where the problem was, battery has been fine since (5 weeks), even though I also only use the car about once a week.
Cut out the alarm by using the actual key to lock the car, as that doesn’t arm it. If all is well, after a week or so use the fob, if the battery goes flat, the alarm is the problem.
Cut out the alarm by using the actual key to lock the car, as that doesn’t arm it. If all is well, after a week or so use the fob, if the battery goes flat, the alarm is the problem.
The battery voltage is only half the story, the capacity is also important (Ah rating). When a battery has been completely discharged and left in that state for any length of time the plates get heavily sulphated and can’t easily be recovered. So even though the voltage looks ok you will find the capacity drastically reduced so it won’t even last more than a few days with the car parked up before it’s flat again. Time for a new battery for sure.
