First check the charger output plug and battery box charging plug is not plugged in. If there is no problem, check if the fuse on the battery box is open or loose contact with the fuse holder. In addition, some models will be able to charge after the battery lock is opened.
If all the above faults are eliminated, consider whether the charger output line is open or not, and use the millimeter voltage to block the 200v block) to measure the charger’s no-load output voltage. It should be 41-44v (with 36v battery due to different chargers). If not, the charger output line may be open, and the charger will be turned on and replaced with an output line to remove the trouble.
Note: when changing the charger output line, you must pay attention to the original machine’s positive and negative poles do not connect.