I've had a 36 series earth X in our apex for about 5 years. It won't hold a charge anymore and is getting swapped out whenever I get motivated (snow is a little sparse here in central mn). It always started the sled even at -25f. Cycle the key, let the pump run, sit for a few seconds, do it again, and third time go for the start. If it was really cold it might require,two start try's but always went. Key seemed to be the prime sequence, letting the battery do a little work to remind it what it's job is, and then holding the key in the crank position till it was actually running.