If possible, find a way to get the coldest possible air to that heatsink. Peltier coolers generate a limited temperature differential, so the cooler the hot side can be kept, the cooler the cold side will be. (Koolatron says 22 to 25 degrees C is typical of their coolers.) I used a Mobicool can cooler (about 20 watts, 22 degree C rated) at work, and in the winter months it would get a can of pop frosty cold, but in hot weather all it could manage was "cool". I've been thinking of scavenging the Peltier cooler from a Koolatron "pro trucker" cooler (maybe 40 to 55 watts?) and turning that into a can cooler. Preferably one that holds several cans if not a six pack.