7 series battery problem

[turbobloke]

Over the past couple of months I've been getting 'charge battery' warnings. Right now and with a new BMW sourced battery coded in, it's flat in two days. The car is an E65 750 sport. Clearly something is draining the battery! I've also had sensor type warnings (e.g. PDC) which don't appear when the battery is freshly charged. Also the SatNav has an intermittent error where the map is swapped for a screen of tiny pastel coloured characters in narrow rows and columns. The issue for me (not a tech at all) is that it willbe likely that some of the issues are due to the low battery affecting control units and sensors, so it's not obvious what single problem could be a cause of the drain on the battery - compared to what could be an effect of it. Has anyone solved anything similar? Any ideas either way? All rational input will be very welcome! I'm asking before the car goes in to my local (very good) BMW independent specialist, hopefully to save on diagnostic time, but that will happen at some point and it would be good to suggest a probable cause up front. TIA.

[danb79]

Do you have comfort access / soft close doors?

If so they tend to be the main culprit with battery drains on the E65s

This was the exact issue I had on my E65 730D M Sport a good few years back

Have you also used the accessory switch in the boot, on the panel above the battery to dumb down the accessories; that will help to stave off any battery drains etc

[turbobloke]

danb79 said:

Do you have comfort access / soft close doors?

If so they tend to be the main culprit with battery drains on the E65s

This was the exact issue I had on my E65 730D M Sport a good few years back

Have you also used the accessory switch in the boot, on the panel above the battery to dumb down the accessories; that will help to stave off any battery drains etc

Thanks, very helpful, I have comfort access (keyless?) but not soft close. I'll chase down that accessory switch.

[danb79]

turbobloke said:

danb79 said:

Do you have comfort access / soft close doors?

If so they tend to be the main culprit with battery drains on the E65s

This was the exact issue I had on my E65 730D M Sport a good few years back

Have you also used the accessory switch in the boot, on the panel above the battery to dumb down the accessories; that will help to stave off any battery drains etc

Thanks, very helpful, I have comfort access (keyless?) but not soft close. I'll chase down that accessory switch.

Deffo try the accessory switch first

But really the best way to fix this is to unplug the comfort access handles and leave them unplugged (tape up the connectors etc)

The wiring perishes in the handles and shorts; causing the battery drain etc

You access them by the bung on the side of the upper door. Pop that out, shine a torch in the hole and you'll see a tab with a hole in it; use a 90º pick tool to get hold of it and pull it towards you, that releases the door handle and it just slides out.

To reconnect; pop the door handle back in and slid the tab forward, locking it in place again

[turbobloke]

Thanks!