Quote:
Originally Posted by Teutonic
Thank you for your reply. Very long charges with those mechanisms working around is a no-no for me.
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With the way BMW has set up the 12v battery to be charged (hood open), the car is almost never in sleep mode. It seems to be always running something in the background. My CTEK MXS 5 has been in float mode most of time. According to CTEK, in float, the charger is providing a constant voltage charge to keep the battery maximally charged. In stage 8, which is pulse mode, the charger only sends a charge when the battery voltage drops below 95% due to self-discharge. My charger only went to pulse stage 8 once but then went back to stage 7.
I hooked up the charger to the terminals in the engine bay and closed the hood without latching it. I then selected AGM mode in the charger and plugged it into the wall. I then locked the doors but my BMW app says the car is unlocked. The charger was in stage 3, bulk charging phase, for about 16h. It got very warm in this stage and I was told by CTEK that is is normal. Once the charger got to stage 4, the charger rapidly advanced to stage 7.
STEP 7 FLOAT
Maintaining the battery voltage at maximum level by providing a constant voltage charge.
STEP 8 PULSE
Maintaining the battery at 95–100% capacity. The charger monitors the battery voltage and gives a pulse when necessary to keep the battery fully charged.