2011 G37 Convertible battery drains after 2 or 3 days and won’t start. I replaced the battery about two years ago. It tests OK and the alternator is putting out 14 vdc. This seems to be intermittent and I’ve discovered that the top doesn’t cycle properly sometimes as well. When I push “open” the windows stay up, there is a motor sound for a few seconds and then it stops. I press close, there’s a motor sound which stops after a few seconds, and I get roof closed message. Now if I push “open”, the top cycles properly. I don’t know if these issues are related nor what to do next. Thanks!

UPDATE: After sitting for two days, the car started fine and the top cycled with no problem. Battery was 12.47vdc and alternator put out 14.44vdc. Had the alternator checked at Auto Zone and appears OK. I drove the car for 35 minutes and checked again: Battery 12.75vdc and alternator 13.38vdc. No error codes or other issues except that the top acted like before. Had to “recycle” to get it opened then closed again. I also failed to mention that the passenger air bag light flashes continuously indicating an air bag system fault.

 

Not sure on the windows / battery drain issue, unfortunately, but we've seen a lot of issues with the passenger presence sensor, which causes airbag light to go off. Worth checking whether it's something related.