Utvärdering av laddningskoncept för lastbilsbatterier
When drivers overnight in the truck lots of electric energy is consumed by heaters, fans, lights and other extra equipment. If the engine is not running, this energy is taken from the lead/acid batteries of the truck which then needs to be recharged during operating hours. The fact that the charge acceptance of the lead/acid batteries is dependent on the temperature makes it hard to fully recharge the batteries at lower temperatures. A negative charge balance can lead to starting problems within a few days use in cold climate.In this thesis work, the effects of different battery charging concept are evaluated on the most common Scania battery (175Ah). A battery model is implemented in Matlab and some simulations of charging are made. Some tests are made in a real truck but the evaluation of the charging methods is mainly based on battery tests made in the laboratory.The methods and procedures for battery testing that were derived during this work are an important part of the results. The variations of charge acceptance with temperature are investigated. The effects of charging at a higher voltage than used today is also evaluated. We find that it is better to raise the temperature of the batteries rather than raise the charging voltage, even though both lead to a better charge acceptance. The internal heating of the batteries during charging are examined and the preliminary results indicate a thermal loss of approximately 10% of the energy the battery is charged with. The thermal loss in percent is the same at room temperature as at -10°C and -20°C.