Absolutely dont use lipos in cold as it severly depletes there charge. The cold does not hurt the battery, it just lets the charge deplete much quicker. As for your charging system.....look at the cost of lipo batteries used in motor vehicles, the cost is really high as there is a built into the battery a regulator so it can be charged off your vehicle, thus the high cost! From my search those that have spent the money on lipos for there vehicles have not been impressed with them. We need to remember that lipos are designed for high draw electrical use, they discharge at a high rate but maintain voltage for a longer period of time, perfect for radio control toys but do we really have high draw in our vehicles?? For that same reason the batteries charge differently, they reach max volts quickly, but then require a slow charge to build up the amps, just oposite of a standard battery.
In our tools like drills you find the drill capable of full power for a much longer time then suddenly stop as a lipo cannot drop below 3.7 volts per cell, if it does the battery wont charge back up. Full charge is 4.2 volts per cell.