1. Main Features: 1. Input & output is fully insolated to endure impact of sensitive appliances and protect the inverter from being easily damaged. 2. High Surge: High surge current capability starts difficult loads such as TVs, camps, motors and other inductive loads. 3. Soft start: Smooth start-up of the appliances. 4. Pure sine wave output waveform: Clean power for sensitive loads. 5. Low total harmonic distortion: Below 5% 6. Stable working performance: Even in the situation of under voltage or over voltage, the inverter could endure 10% voltage fluctuation until it shutdowns. 7. Cooling fan with internal temperature sensor will turn on automatically when the inverters becomes warm and turn off after the temperature dropped. 8. LED indicator on the front panel shows the working and error state. 9. Digital displays indicate battery voltage and inverter output voltage. 2. Protect functions: 1. Over load protection 2. Over current protection 3. Over voltage protection 4. Low voltage protection 5. Surge protection 6. Short circuit protection 7. High temperature protection 8. Reverse connection protection 9. External fuse protection 10. Buzzer alarm function 3. Applicable for: ( Solar/Wind/Home System ) 1. Travel set equipment 2. Industrial equipment 3. Office equipment 4. Kitchen equipment 5. Household electrical equipment 6. Power tools 4. Technical Parameter:  Input: Input voltage: DC12V/DC24V/DC48V Working Voltage: DC10V-15V/DC20V-30V/DC40V-60V Input current: 333A/ 166A/83A Standby input power: 4200W Short circuit protection Digital display Indicator:  Inverter woking: green light on Inverter problem: no 110V/220v display Charging indicator: digital of voltage up slowly Charging process indicator: digital display charging voltage Turn off the switch when charging which charging battery faster Protection alarm:  Low input voltage alarm: buzzer Low input voltage protection: no display, buzzer and inverter stop working High input voltage protection: no output voltage display, have input display, inverter stop working. Over load protection: voltage drop to 55V-140V Abnormal temperature: no AC display, buzzer and stop working. Environment: High temperature protectioin: =70ºC Working Temperature: -10ºC~40ºC Cooling mode: Intelligent Temperature control Fan Package included: 1* QW-P4000UPS 1* battery clamp 1* spare part 1* english user manual 1* standard packing box 5. Warranty: 12 months    Quality stanstard: CE, RoHS