Check your battery before charging:
The 5V 120mah and 5V 400mah Charger are suitable for 5V KR808d battery.
The 4.2v 420mah Charger is suitable for 4.2v battery.
The 808D USB Charger with IC protect for 808D thread electronic cigarette Battery
1. 808d Universal USB charger.
2. Short circuit protection, over charge protection.
Input:DC 5V 500mA
Output:DC 5V 120mA