Quote:
Originally Posted by rusty_tlc
I thought the 24V thing was because of the initial starting power required, ie it's easier to deal with 24V at a lower current than 12V at a higher current. The diesels use a lot more power at start because of the glow plugs right? I'm not sure how NATO figures into it.
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Not really so much because of the glow-plugs themselves. Their only purpose is to heat the engine on a cold day so that combustion can occur more easily. If the engine has already been run for a while and is at operating temperature, they may not light at all. Some bigger commercial type diesels don't even use glow-plugs.
I think the main reason for the military/NATO specification of 24V systems is the efficiency, lower weight, and usually lower cost of such systems. These factors come into more focus in heavy-duty use. In some cases I think you are correct in that the greater starting power can also be useful, especially in colder weather. Also, it has evolved as the standard of most/all militaries and allows for commonality on the battlefield (I picture a British Land Rover jump-starting an American Abrams tank, or maybe that should be reversed...).
The point I was trying to make was that the choice of a 24V system is not always related to the type of engine. Sometimes it is a functional specification, sometimes an organizational one, sometimes both. But either gas or petrol engines can run on either 12V or 24V.