The battery car charger is normal, and the reason for burning 3842 and the field effect tube with the load may be that the current is too large due to the load, which exceeds the carrying capacity of the charger.
When the battery car charger is in the no-load state, the current is small, and the charger can work normally.
However, when the load is connected, the current will increase, if it exceeds the rated current of the charger, it will cause the charger to overload, which will burn out 3842 and the field effect tube.
In order to solve this problem, you can consider the following points: 1. Check whether the rated current of the charger and the current demand of the load match, if not, you can replace the appropriate charger or reduce the load current.
2. Check the heat dissipation of the charger. If the heat dissipation is poor, take heat dissipation measures, such as adding heat sinks or fans, to improve the heat dissipation effect of the charger. 3. Check whether the circuit design and components of the charger are normal. If there are damaged or aging components, they need to be replaced and repaired in time. In short, the battery car charger is normal, but the reason for burning 3842 and the field effect tube with the load may be that the load is too large leading to the overload of the charger, and it is necessary to check the current matching, heat dissipation and circuit design, and carry out the corresponding repair and adjustment.
First fix the charger, do not connect the battery, but connect a 220V\/100W bulb to see if the output of the charger is normal.
Then check whether there is a short circuit inside the docking plug with the battery.
Remove the battery to see if there is a problem with the connection line, and measure whether the battery has voltage to determine whether it is an internal short circuit.