Hi

Got up this morning to a flat battery (5.6v) after locking car last night with key fob button.  Charged battery and took it for a run - all seemed good.

Tonight noticed that my media player was showing an active bluetooth connection to SYNC.  Checked the car and saw that the display clock was lit.  Car was still locked, but key fob button wouldn't unlock it - had to use key in lock.  Started engine OK, but the remote locking isn't working and the SYNC display is still lit.

I've turned off Bluetooth in the car.  Expecting to have to charge the battery again tomorrow morning.

Any ideas why and how to track down issue would be gratefully appreciated.

Disconnect the battery for 20 minutes. Then reconnect.

When you charged the battery did you leave it connected on the car ?

Hi and thanks - I disconnected the +ve lead only.  I'll do both tomorrow if it needs charging.

The BMS module is confused.

If you need to charge the battery in future, leave it connected to the car. Connect the positive lead of the charger to the positive terminal of the battery, then connect the negative lead of the charger to the chassis earth point near the battery. Do NOT connect the negative lead of the charger direct to the battery negative terminal.

Tomorrow after disconnecting and reconnecting the battery you should also reset the BMS (You don't need to do that if the battery is cahrged on the car).

 

 

Thanks for the info - battery is 9.5V this morning - so charger is connected as you suggested.

Ok.  Charged the battery and then placed my multimeter in series on the positive cable.  It's drawing 2A - so definitely a drain somewhere.

Pulled each fuse in turn in the engine bay - fuse F5 dropped the reading - so the issue is in the glovebox fusebox.

Pulled each of those in turn - Fuse 28 - I don't have start/stop, which implies either F19/21/23/24 - none of them reduce power drain if pulled though.

Close... But no cigar.... Yet !

mmmm...... very difficult to trace this kind of fault. Couple of things to remember while doing this (a) keep the car key/fob well out of range of the car, otherwise the car will sense the key and wake-up certain modules. (b) After you switch off and lock-up the car it take about 20 minutes for all modules to power down and go to sleep.

To fault find on this is a real problem, you need to sit inside the car with everything powered down, then wait 20 minutes before starting to look for the power drain.

Little tip which speeds up checking each circuit is to set your multimeter to mV and then measure across the fuse whilst it is still plugged in. If the circuit is live and there is a current going through the fuse then you will measure a mV drop across the fuse. Doing this saves you having to pull each fuse and will give an acurate result.

55 minutes ago, unofix said:

mmmm...... very difficult to trace this kind of fault. Couple of things to remember while doing this (a) keep the car key/fob well out of range of the car, otherwise the car will sense the key and wake-up certain modules.

Wow... What sort of range ?  I keep the keys overnight (house) about 10 ft from the car (driveway) - line of sight through a window !

Hi Simon, 10ft through a wall is probably far enough away. You can test it yourself if you have keyless entry. Leave the key in the house and go out to the car and try the doors.

If you are doing fault finding on the car just keep the key away from it otherwise it will start to turn some modules to a ready state.

If your battery is reading 9.5 Volts, arrange a memorial service for it and order another one.