July 8, 2007: The new version of the American AN/PAS-13 thermal sight is a wonder to behold, as it enables infantry to see through darkness, mist and dust storms, because it can make out differences in heat. But these useful devices have a downside, they go through batteries at a prodigious rate. The AN/PAS-13 actually comes in three sizes, to accommodate longer ranges of some weapons. The smallest one, weighing 1.8 pounds, is used on your basic M-16 or M-4 assault rifle. This sight has a range of 550 meters, uses 4 AA batteries (lithium, as used in cameras). That gets you about 5.5 hours of use. These batteries weigh about twenty per pound and cost the government about $1.50 each. Now consider that your average infantry battalion will have several hundred of these sights. Do the math. It adds up. On many operations, a unit will use more batteries than ammo. These batteries are slightly heavier, and four times more expensive, than 5.56mm rifle ammo.

The next version weighs 2.8 pounds, has a range of 1,100 meters and is used in 5.56mm and 7.62mm machine-guns. This sight requires six AA batteries (for 6.5 hours). The heaviest version weighs 3.9 pounds, has a range of 2,200 meters, and is used by heavy machine-guns and snipers. This one also requires six AA batteries (for 6.5 hours).

When possible, the troops try to rely on the thermal sights in armored vehicles, as these run off the vehicle electrical system, and can go all night without worrying about any battery issues.

The new version of the sight will start showing up in Iraq and Afghanistan by the end of the year. Unless there is a much improved new version in the next few years (no one is sure, engineers can be unpredictable), the army plans to buy as many as 150,000 AN/PAS-13 sights (at a cost of over $10,000 each). Battery cost not included.