Auxiliary Power Units
Auxiliary Power Units (APUs) are units added to trucks to reduce reliance on the main diesel engine for electrical power, heat and air conditioning, maintaining batteries at full charge, or keeping the main engine coolant at close to operating temperature. The use of an APU can lower fuel costs by up to 90% compared to idling on the main engine and reduce emissions.
There are many different brands of APUs on the market but they generally fall into three types:
A key consideration for APUs is installed cost versus payback. Technology suppliers may offer calculators to estimate the payback time for a specific application. See, for example, the calculator at Kohler.