By Paul Abelson, senior technical editor
The commercialization of inverters has increased the flexibility of electric power. By converting 12-volt direct current (DC) to household alternating current (AC) at 110-120 volts, truck owners can choose from among 12-volt appliances or less costly home appliances like small, safe ceramic heaters.
Electric power has gained popularity in recent years for several reasons. Inverters that once cost thousands now cost hundreds for even more capable units. Alternative sources for plug-in electric power are starting to be installed at truck stops, at company yards and at shippers and receivers. And advances in battery design let group 31 truck batteries do double duty. Absorbed glass mat (AGM) batteries have high density, pure lead plates that hold a strong charge for good starting but can be more deeply discharged like a marine battery.
AGM batteries are used in many hybrid heating, ventilating and air conditioning (HVAC) devices. A battery powered air conditioner coupled with a fuel-burning heater can provide hotel comfort without the noise and vibration of a generator or APU.
There are no limits when using plug-in A/C, the limitation with battery HVAC units is the power in the battery system. Most four-battery banks can run air conditioners in reasonable climates for the 10-hour mandatory rest period. But warmer climates shorten the time the A/C will run. For hotter climates and extended operations, Bergstrom added a small, quiet Kohler generator to their NITE system. With the generator, it’s the NITE Plus. When batteries deplete, the generator’s sole task is to recharge them.