Hello, there is something I do not understand when charging lead acid batteries (or batteries in general). Somehow chargers intrigue me... Specifically it is about my motorcycle's battery, it's a 7Ah one. When I connect a mains charger to the battery the voltage gradually rises (it takes hours) from let's say 12.6V to 13.2V. The charger is of 600mA output. However when the battery is connected to the engine and rev the engine, the voltage instantly rises to 13.2V-13.8V not gradually. What does this mean? What is the difference of charging type that motorcycle's electrical system does compare to the mains charger?