Storage and Transfer
Auxiliary and Back Up Batteries explained
Auxiliary Battery Overview
Modern vehicles with CO2 reduction technologies, high levels of specification, and new electronic driver aids may feature an auxiliary battery alongside the main vehicle starter battery or high voltage system battery on Hybrid and electric vehicles. Auxiliary batteries vary in size and specification dependent on the demands placed on it by the vehicle electrical system and can be used as a safety back-up to support the main battery when required or to provide voltage for specific vehicle systems all of the time.
Internal Combustion Engine Auxiliary Battery
Mercedes E and S Class vehicles feature driver aid systems such as Sensotronic Brake Control (SBC). This system is a brake by wire system that converts driver brake pedal pressure into electrical signals and uses a control module, hydraulic pump, accumulator and pressure distribution valves to apply exactly the right amount of braking pressure to each wheel dependent on inputs from various sensors and vehicle driving conditions.
As this system relies on electrical power and a minimum system voltage to apply the brakes the vehicle is equipped with an auxiliary battery as a safety back-up which becomes operational in the event of the main starter battery becoming too low or a charging system failure.
Hybrid Vehicle Auxiliary Battery
Most Hybrid vehicles such as the Toyota Prius feature a conventional 12 Volt auxiliary battery in addition to the high voltage hybrid system battery.
The 12 Volt battery is not used for engine starting or to power the traction motors but is used to supply power to:
· Accessory systems
· Audio systems
· Computer controls
Electric Vehicle Auxiliary Battery
Electric vehicles such as the Mitsubishi i-miev feature a conventional 12 Volt auxiliary battery in addition to the high voltage traction battery.
The auxiliary battery is not used by the traction motor but is charged by the traction battery and is used to support all of the electrical systems on the vehicle with the exception of:
· Air conditioning
· Heating system