Commercial Long-Haul Truck with Sleeper (Class 8 - USA) Battery System
Over their lifetime, the starting batteries for a Class 8 truck must consistently deliver high cold cranking amps, which can be especially challenging during extremely cold weather. With the engine off due to idling restrictions, a high cycle reserve capacity is required to support key-off loads such as lighting, dashboard electronics, GPS and monitoring systems. The alternator is the sole charging source.
Battery failure is most commonly caused by acid stratification, extreme temperatures and destructive over-the-road vibration. Acid stratification naturally occurs in flooded lead-acid starting batteries and leads to a decline in capacity and charge acceptance. AGM technology and acid mixing technology for flooded lead-acid will mitigate acid stratification. A maintenance-free spill-proof battery is highly desirable.
‘Hotel’ loads in the truck sleeper should be supplied by a separate bank of ‘House’ batteries which will be deeply cycled regularly. House batteries should be sized to support the hotel loads over a standard rest period (8-10 hours). House batteries need to support the surge current of the inverter during load startup. The alternator charges house batteries, but after the starter batteries have been charged. Undercharging of the house batteries can occur due to undersized cabling and the voltage drop across the battery isolator/combiner. Trucks with inverter-charger systems can usually be plugged into ‘shorepower’ to ensure correctly and fully charged house batteries. State of Charge (SOC) monitoring will be helpful to the truck driver.