Look at the brand. The car out of the big factory long life, reliable quality, some electric bike parts will do very well, save maintenance costs.
Look at the appearance. Look at the color. How new is it? Do not buy too old, batteries are basically useless, do not listen to the seller said how many kilometers can ride. In the case of a newly changed battery, he was asked to provide an invoice for the purchase of the battery. You have to try it by yourself, don’t ride slowly, you can’t try out the quality of battery.
Look at the voltage indicator of the battery (that is, the electricity pointer) to drop fast or not. If the drop is fast and slow again, it means the battery is not good. The battery is good if you come back quickly. It’s useless to drop back.
Circuit part check, including lamp, horn, total switch, electric handle, brake power cut, charger, battery box, etc. Try headlights, turn lights, brake lights, instrumentation, and each switch is working. In addition, listen to whether there is abnormal noise when riding, running with or without power, and riding for a certain time to see if the heat is abnormal, if there are conditions, check the motor current. See if the current is in the normal range. If the current is too large, the motor aging is serious.