WindyChuffer
Registered user
This why i always hook up accessories direct to battery with ignition switched relay. At least you are in control (as opposed to a german software goblin that decides to randomly eat your battery).
the OEM bmw batttery is fine.
At each exhaust camshaft there is an centrifugal-force-driven decompression facility which facilitates the start-up process. This makes it possible to save weight in the starter motor and battery.
So the BMW chap came out ... got it started off jump pack then took out for 20min spin before putting battery checker on and all came back as a good battery. I had a accessory cable on the DIN plug but no accessory he thinks that has drained battery must say Im not convinced as if it has nothing connected its just an extension to the DIN plug ... Anyway on the AC BMW the DIN did not work with ignition off i guess the LC one is opposite I need to check. Anyway taking it down to dealer tomorrow they have agreed for new battery as Im off on 4000m trip in just over a week and not having nagging doubts every morning ....
Sorry just realised Ive double posted similar comment .... Im new on here![]()

The OEM battery is 12ah.
That is pathetic........especially on a large capacity bike with an advanced electrical system that has a parasitic draw on it.
The Motobatt direct replacement is MBYZ16H, it will cost less than 60 quid and it's 16ah.
Even that is pretty low powered.....the Motobatt on my 1150 is 22ah.
12 is ridiculously underpowered for the bike.
OK got bike back now and the explanation given makes sense but I guess Im not the only person who has done this so surprised Ive not heard more about it.
I left and accessory cable plug into the DIN socket next to dash, although nothing was attached to the cable (i.e. phone) the cable had a voltage regulator in-line. This was enough to keep the can-bus line open and as such one or some of the bikes ECU's didn't go to sleep and this is what drained battery.
If you plug into the DIN and turn ignition off it will delivery 12V. If you turn ignition off and then plug into DIN socket you get nothing.