The book instructs you to conect a charger via the under bonnet posts.Busterboo wrote: ↑Mon May 21, 2018 10:58 pmCan you use it on an E89 through the cigarette lighter?mentalnerve wrote: ↑Sun May 13, 2018 12:37 pm I've got ... the ctek mxs7 £80 with the cigarette lighter plug ...
With the amount of electronics these cars have I won’t argue with their (BMW) instructions.
My charger was an cheapo under £10 job from Makro many years ago - designed for liesure batteries and golf carts - it cycles the battery but doesn’t fully charge nor discharge, something like 12.5v up to 13.5v it’s done the job over the last seven or eight years .
I used it over last winter and it started on the button in May - I did put the voltmeter across the posts once in a while and it was always in a positively charged state.