XSeries-forum

You really need to put the battery on a smart charger before you fit it- even new they can sometime take 24 hours to get to 100%, if you’ve got a charger hook it up until it is properly charged.

Did you fit a new resistor for the heater yet?

New resistor fitted a few days ago, blower all seems to be working ok now.
I'm going to put a clamp meter around the cable under the bonnet and see what happens over a couple of hours, I'll also measure the voltage of the battery over the same period, it might not be precise but it will give me some idea of whether there is a drain on the battery.
If there's a better way of doing it then I'm all ears.
I will also connect up a smart charger overnight anyway, just to make sure the battery is 100% charged.

Just done a very quick check with the clamp meter, first picture shows with engine running
Second shows with the engine is off.
I then thought it might be a dodgy bonnet sensor or something, so I set the alarm with the bonnet open and nothing happened, as in, no warning etc. Should there not be a warning to say something is open.
I did the same with the door, set whilst it was open, same, no warning .
I then alarmed the car and opened via the key and the alarm sounded as it should.
I find that all a bit strange that I'm not getting a warning about something being open.

Sure I just posted but it didn’t appear, apologies if it appears twice!

You might have to get one of those adapters so you can check the current draw on each fuse way, after the car has gone to sleep after 16 minutes.

I take it the little orange light by the gearstick does go out?

I think X5Sport might know about how to do it, I’ve defined seen it described on the forum before, there some way of doing it without waking the car up I think

Not sure about the alarm thing to be honest, when I locked mine with the bonnet open and the charger connected I don’t think it made any objections or warnings

Do you mean this light?
How long before it should go out?

Just checked and the light is out.

Yes, It goes out after 16 minutes- that’s when the car is asleep, and you should be down to something like 0.1a current draw if I remember rightly - don’t quote me on that number though!

Id bypass the bonnet sensor as these used to be a favorite for setting the alarm off on other bmw's It seems it only goes off when the alarm is armed so locking it manually at night may be the way forward for now .

Bonnet switch is a very common culprit on the E53. They get wet and corrode inside which causes problems. Asleep the car should be less than 100mA depending upon what options are fitted. Some can be below 80mA.

I don’t remember my alarm going off if I locked the car with the bonnet open, but it would go if the switch was touched (reacting to a changed state from when armed). Two presses of the key fob lock button disables the interior sensor - in case that might be the issue?

Battery is hooked up to the optimate overnight, so hopefully a fully charged new battery by morning, car is locked via the key, not the remote, we don't have many neighbours, but I don't want to annoy the few we do have with the alarm going off in the early hours of the morning.
I'll try a few things that have been suggested and gradually eliminate things.

Wed morning battery was reading 12.6v after being hooked up to optimate overnight, used the car wed for a couple of journeys.
Locked the car using the key, not setting the alarm, this morning its reading 12.3v.

I have a Bluetooth battery monitor on mine and 12.3v is what it shows but that is when the car has been standing all week.
Never checked it a day after running it.
Did you wake the car up ?? and then check the voltage as it will drop a bit when you wake it.

All I did was open the door with the key, not sure if that fully awakens the beast or just stirs him gently, lol.

Have now checked the voltage several times, it seems that even opening the car via the key takes a bit out of the battery initially, then when the car goes into sleep mode again the voltage comes back up to 12.6v.
So it would appear that the battery drain was either down to a tired battery, ( I've since fully charged the old battery up to 12.6v but the indicator on the top of the battery is still showing that it needs charging ), or it's something alarm related, ( as I've only been locking the car via the key for the last couple of days ).

As soon as you open a door, or trigger the locks it wakes some of the systems up. That will pull the voltage down until the car goes to sleep again.