They build a unit today that senses the temp on the engine and it is started automatically to keep the prime mover at a temperature that will prevent freezing, and yes a good set of batteries are needed.
On the other hand having dealt with air starting systems for large diesel generators they run on 250 pounds of air, cold diesels are sometimes hard to start and most of those systems had both an AC powered compressor and a DC powered unit, one problem in the winter, air tank controls freeze from the accumulated water that occurs when air compressors charge up storage tanks.
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