I've used older similar 25 A model CTEK charger for many years without problems. In constant use some 7 A CTEK models have failed on me after a few years. If I would have to choose now I would probably go with Victron Energy blue smart charger.

Actually coding these older vehicles doesn't require power source. It takes such a short time and coding is not so voltage dependent. Programming/flashing is a different thing where stabile voltage is paramount.

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E39 530dA -02 M-Sport Messing metallic
E53 X5 3.0dA -06 Sport Stratus grey
E70 X5 40d -12 M-Sport Space grey