It all depends upon what type of battery is used. For example, a lead-acid battery that provides 12V, has 6 cells. Each cell provides approximately 2V. For lead-acid batteries, it's roughly 2.2 Volts per cell charging Voltage, or in this case 13.2V. The charger must have more Volts than the battery so the electrons flow to the battery. Using a DC to DC power booster probably won't work. It's not designed to be a battery charger. Sure, it will put some charge into the battery, but you will run the risk of and exploding battery from over charging.