1. Car charger adapter with voltage detection function: Normal car battery voltage is 12.5V the generator operating voltage after starting should be 14V ± 0.7V; If voltage is lower than 12V it might be battery aging / circuit leakage or vehicles not used for a long time; The instantaneous voltage of twisting the key to light a fire should not be less than 9V if it is you may change the battery or charging for it (according to the battery operating time and service time); After startup if the voltage is below 13V the generator may be a problem with the generator belt slippage or electricity or vehicle overloading (you can try to turn off all electrical appliances); If the voltage is higher than 14.8V or above 15V the generator can not automatically adjust the voltage and quickly turn off. 2. Dual-USB charging interface supports charging for two USB devices at the same time.