APU’s are units added to trucks to reduce the use of the main diesel engine to provide key services to a truck such as 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 of the main engine.
There are many different brands of APU’s on the market but they generally fall into three types:
Small Diesel APU – a small diesel engine powers belt driven accessories is used to provide services to the cab and main engine
Small Diesel-Electric – a small diesel engine runs a 120V generator that powers accessories. This technology is typically designed to also plug into “shore” power making for a zero emission tractor at some rest stops.
Battery-Electric – This all battery APU provides electricity to operate accessories and has a small diesel fired heater. The system is recharged either via the main diesel engine or shore power.
A key consideration for APU’s is installed cost vs. payback. Here are three technology supplier calculators that can be used to estimate the payback time for your specific application.
Some jurisdictions in British Columbia and elsewhere impose restrictions and fines on idling a truck’s main engine. APU’s may be a necessity for trucks operating in these jurisdictions.