E53 battery drain advice please.

[Estoril daz]

Hi,

I'm having trouble with my battery, it's slowly draining and causing problems starting the car. I have tested battery and is showing 14.5v whilst car is running, then an average of between 10-11v with car off.

Car is entering sleep mode, fans off etc and all seems well.

Iv ran a parasitic drain test and it's showing 0.03a when asleep, however the nav drive cycled on during the test and shot up to 3.00a.

I'm not sure why it came on, or even if it should. It span the disk for approx 30sec then shut off.

This did not awaken the car though.

Any thoughts?

[X5Sport]

Your battery is down one one cell.  A good, fully charged battery should be 12.6V.  Anything between 10-11V needs replacing.  It should be checked from under the bonnet, four hours or more after last use and with the car asleep (leave the bonnet open and lock the car).

Your alternator seems fine with those figures.  And the sleep drain looks OK too.

Unlocking the car, or opening a door etc will cause the Nav Comp to spin up.

If your battery has a 'tell-tale' window on it then it might well be yellow in colour indicating a dying battery.  Also check for the production date code (4 digits) for week/year and if it's four or more years old then it is EOL.  6 years is doing very well if it's that old.

Richard

[Estoril daz]

I shall replace the battery as I agree it's the main problem.

My concern is the nav unit but it's probably just me worrying, I just can't see why it may cycle on for 30 seconds then shut off again whilst nothing had been pressed or touched... (Still in sleep mode)

Thank you

[X5Sport]

It might be because that generation took so long to start up, any change on the car causes it to leap to life...just in case?

[Estoril daz]

Makes sense to me, I'm sure it's just the battery.

Will order one now.

Thank you for your help.