SR-700 DC-100/600 DA-300/600/1200 BC/SC/MU Battery Charger
Q1. Why there is always low input voltage alert or alarm but the battery is full?

A1. Use larger input cable size and shorten its length as the voltage drop across the input
cables affect the sense voltage at the input of the inverter. Especially under heavy
loading condition.

Q2. What cable size should be used?

A2. In order to reduce the voltage drop across the input cables, following minimum cable sizes
of about 1 metres are recommended for different inverters.
Model 12V Input 24V Input
DA-300 AWG#12 AWG#14
DA-600 AWG#10 AWG#12
DA-1200 AWG#8 AWG#10

Q3. Can the inverters connect to common electrical/electronic appliances?

A3. DA series inverters are MCU based inverters with digital contorl. This enhances
the implementation of modified sine output with higer line fundamental frequency
(50Hz/60Hz) component. It is suitable for most electrical/electronic appliances
such as flourescent lamps with standard ballast or electronic ballasts, electric
hand-drills, electric fans, heaters, hair dryers, heat guns, pumps, etc.. The maximum
current linear derating factor is approximately 1A/deg C.

Q4. How to calculate the output power for specific loading?

A4. It is easier to calculate the output power for resistive load such as heaters and
light bulbs . More attention must be paid on inductive and capacitive load (i.e. power
factor is not equal to one) such as flourescent lamp with standard ballast and motors.
It is better to use only about half the rated power of the inverter for inductive or
capacitive load. Below is a typical example for DA-300-12-2 to power flourescent lamps
with standard ballasts.
Input Volt. Input Current Flourescent Lamps Output Volt. Output Current Calcuated VA
12VDC 10A 2 x 40W 220VAC 0.75A 165VA
12VDC 15A 3 x 40W 220VAC 1.15A 253VA
12VDC 19A 4 x 40W 220VAC 1.52A 334VA

Q5. Why the inverter always OVP?

A5. OVP is activated when a high voltage is detected at the output of the inverter. It usually
happens under inductive load and load with switching cuurent. The problem may be solved by
shorten the output cable connecting to the load.

Q6. What is the body temperatuer of the inverter at rated output power?

A6. The body temperature is about 25 deg. C above ambient temperature at rated output power.

Q7. Why a DA-300 inverter cannot start with a 12V 30A power supply under full load condition?

A7. Power supply with current limit decreases its output voltage when the drawn current exceeds
its limit. Under full load condition, the surge current can be several times that of the
steady current. This activates the current limit of the supply and triggers the under voltage
protect of the inverter. It is recommended to use batteries to power the inverter.

Q8. Why the input terminals of the inverter get hot?

A8. The contact resistance between the input cables and the input terminals of the inverter is
too large. Always connect the input cables with tags of large surface areas. Do not just strip
the cables and wrap them on the terminals.

Q9. Where should the earth/ground wire of the electric appliance be connected to?

A9. Since the inverter is powered by DC power, therefore there is no earth/ground connection for
electric appliance. Just leave the earth/ground wire unconnected.

Q10. How to identify the live and neutral terminals from the output of the inverter?

A10. There is no need to identify between live and neutral terminal at the output of the inverter.

Q11. Will the inverter be damaged with wrong dc input polarity?

A11. The inverter is protected against wrong dc input polarity. It will not function when the input
is connected wrongly.

Q12. Can several inverters be connected in parallel or series?

A12. Do not connect two or more inverters in parallel or series as they are not synchronized. This
will damage the inverters.

Q13. What is the advantage of digital control inverter as compare with the analogue one?
A13. Digital control inverters are more robust. They can withstand more serve and varying loading
condtions as compare with the analogue inverters. Also they are more stable under the software

Q14.. How to calculate the capacity of the battery for a known loading?

A14. It is very difficult to calculate the capacity (AH) of the battery used for a specified load
because it is depended on the battery conditon. A typical example for rated output powers with
160AH 12V and 24V batteries are for reference.
Model Rated Output Power 12V 24V
DA-300 250W 6 hours 12 hours
DA-600 500W 3 hours 6 hours
DA-1200 1000W 1.5 hours 3 hours