The transformer with two coils can not be used, it can only be used for alternating current, can not be used for direct current, if it is instantaneously increased to 10 can use ballast, there will be high voltage between power and power, but permanent improvement, or add a few batteries. It can be connected with a wire, not necessarily a battery box.
According to the basic principle of the circuit, the way to change the voltage of the lithium battery is usually to increase or reduce the number of series batteries to change the voltage value, when the series battery is increased, the voltage increases and the voltage decreases after the series battery is reduced, but the battery used must be the same voltage level of the battery