Ramsond SunRay 1500 and 3000 Inverters
Instruction Manual (v. 34411)
©
Ramsond Corporation. All right reserved. Ramsond and Sunray are trademarks of Ramsond Corp.
Page 15.
Load Considerations
When an appliance with a motor starts, it requires a momentary surge of power. This surge of
power is the “starting load” or “peak load”. Once started, the appliance requires less power to
continue to operate. This is known as the “continuous load”. It is important to know starting
loads and continuous loads of appliances that will be powered by the inverter. Appliance power
is rated in watts. This information is usually stamped or printed on most appliances and
equipment. In some cases, a tool will be rated in amperes. To convert from amps to watts,
multiply: AMPS × 11 5 (AC voltage) = WATTS. Then multiply this number by 90% (the efficiency
of this inverter). This formula yields an approximation of the continuous wattage load of that
appliance.
The startup load of an appliance is a major factor of whether this inverter can power it. Startup
load is momentary. With many appliances, it is approximately twice the continuous load but
some appliance startup loads can be as high as eight times the continuous load. To determine if
an appliance or tool will operate with this inverter, run a test. This inverter will automatically shut
down in the event of an output overload, so there is no danger of damaging either the inverter or
the equipment. This inverter may not properly operate some appliances with either speed
control features or dimmer controls. Some appliance GFCI power cords will not operate properly
while powered by this inverter. The only way to be sure of proper operation is to try it.
Configuring the Battery Bank
To determine the minimum battery ampere-hour rating that you will need to operate appliances
from the inverter and any DC appliances powered by the battery bank, follow these steps:
1)
List the maximum continuous wattage that the inverter has to supply.
2)
Estimate the number of hours the appliances will be in use between battery recharges.
This will vary depending on appliances. For example, a typical home use coffee maker
draws 500 watts during its brew time of 5 minutes.
3)
It maintains the temperature of the pot, requiring 100 watts. Typical use of a microwave
oven is only for a few minutes. Some longer operating time appliances are lamps, TVs,
computers and refrigerator/freezers.
4)
Determine the total watt-hours of energy needed. This is done by multiplying average
power consumption in watts by hours of run time. For example: 1,500 watts for 10 hours =
15,000 watt hours. To get an estimate of the maximum current (in amps) that a battery
bank must be capable of delivering to the inverter, divide the load watts by ten. For
example a 1,500 watt appliance load will need 150 amps at 12 volts DC. Using the 1,500
watts (or 150 Amps) for 10 hours example as above, then 150 amps is needed for 10
hours. This provides us with the basic amp hours (Ah) of battery that is required. Ten
hours at 150 amps equals 1,500 Amp hours (Ah). This answer is just a beginning because
there are additional factors that determine actual run time. These include:
AC appliance load and time in use (basic Ah).
Cable gage and length (cable losses).
Charge level of the batteries (between use, chargers have to be
able to fully charge the batteries).
Temperature of the batteries (colder batteries provide fewer
amps).
