Help me out guys…
About two weeks ago we left the range overnight at the pub and when we went to get it next morning it was completely flat wouldn’t even click just interior lights on. We had walked so walked home which is about a mile and about 7 hours later drove up in the m6 with some jump leads. Just for giggles I put the key in anyway and it started (although slow cranking) firstly how is that possible?

Anyway then it was running and the side steps had turned themselves off so o switched them back on…

Next morning it was hard starting again like dying battery and the Christmas tree dash was on and the steps had switched themselves off again like they do with a low battery. I drove around all day it was fine - I left the steps off…
I pushed it and drove for a further 10 days even with a couple of days between driving… no problem… this morning I turned the steps on… yesterday evening it’s dead and not even trying to crank…disabled the steps and it’s been fine today?

I’ve notice that when the steps are disabled the are both half out / half in? Any ideas what that means? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Hi Dan,
This is a familiar issue, especially at this time of year.
I suspect you have a combination of a weak battery and gummed-up steps.
The cold weather depletes battery capacity and the sluggish steps draw more current.
Leaving the car for several hours allows the battery to partially recover, and because the steps are then deactivated, when you unlock the car, there is just about enough juice to get it going.

Time for a new battery and a sidesteps relube, methinks!
(Better than getting marooned on a freezing night, far from home!)

Check the battery SOH first (not the battery SOC) before purchasing.

Buy a CTEK, and leave it plugged in as much as possible!  “If it ain’t broke, don’t fix it” -where’s the fun in that?