First: If battery voltage drops and if the HVAC fan will not function, placing a cover on the grill is not a remedy. E.g., Higher radiator core temps will not increase battery temp / voltage.
Second: The places in Canada with average low December temperatures anything like you suggest are places like Yellowknife (-27C), Inukjuak (-21C) and Winnipeg (-11C).
So, unless one has a 335d in one of these places (and why would you chose a 2-wheel drive diesel in one of these places anyhow?) it seems highly unlikely that the scenario you suggest would arise. Not that is was not cold where you were, but that is not a common environment and, your low voltage issue is not related to radiator core temp. Accordingly, while batteries will experience a cold-related voltage drop- the system should carry the proper voltage once recovered from starting / glow plug load. Perhaps your car has a battery / charging system issue.
Would this thing even start at -30C unassisted?
Last edited by ihbase; 01-01-2013 at 08:11 PM.