My battery is 5+ years old and dying, I would like not to lose all presets during the exchange. I am wondering if the current from a 2A float charger attached to the engine bay connector would be damaging to the electronics without a battery buffer attached to the aft power bus (obviously avoiding any metal contact to + connectors)? I do have the option of using another battery, just a lot more trouble.

 

The only thing you will lose is the auto up/down window and the hatch soft close when you do a battery swap on these cars, and both of these are very easy to reset.

 

And the float charger may not continue to work when you disconnect the battery. As Thunder Dump says, it’s really no big deal to disconnect the battery.

 

I can confirm that after I´ve disconnected the battery for many hours (flooded trunk) I did not lose anything but the auto windows function and the time/date setting.

 

You can also easily connect a second 12V battery across the engine compartment terminals while replacing the main battery, then all will be saved.

 

I tested this with my CTEK MXS 5.0 and as soon as the battery was disconnected the voltage across the leads dropped to zero. Easiest(?) to connect a spare battery to the underhood terminals. Or a real charger, of course.

 

I just swapped batteries…takes 5 minutes to set time and do a quick search on how to reset the auto windows (cause I didn’t remember). Easier than connecting another battery I say.