Power Bright ERP3500-12 - Manuel (Page 8)

Sizing the Battery
To determine the minimum battery bank 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 wattage that the inverter has to provide (as above).
2. Estimate the number of hours the appliances will be in use between
battery recharges. This will differ depending on appliances. As an
example, a typical home-use coffeemaker draws 500 watts during its
brew time of 5 minutes, it maintains the temperature of the pot at about
100 watts. Typical use of a microwave oven is only for a few minutes.
Some longer operating time appliances are lamps, TV's, computers and
refrigerator/freezers.
3. Determine the total watt-hours of energy needed. Then multiply the
average power consumption in watts by the number of hours of run time.
For example: 2000 watts for 10 hours = 20,000 watt hours.
Using the 2000 watts (or 100 Amps) for 10 hours example as above,
then 100 amps is needed for 10 hours. This provides us with the basic
amp-hours (AH) of battery that is required. Ten hours at 100 amps
equals 1000 Amp Hours (AH). This answer is just a beginning because
there are other conditions that determine actual run time. These include:
• AC appliance load and time in use (basic Amp Hour)
• 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)
• Age and condition of the batteries (older batteries lose capacity
(amp hours)
• Compliance with turning off unnecessary AC and DC loads.
If there is any doubt about sizing the battery bank, it is safe to over
estimate the amp hour requirements of the battery bank.
Note:
The type of batteries you use to power your high power inverter is important.
Operating a high-power inverter will routinely discharge batteries and they will
require frequent recharging. Batteries used to start engines are not designed
to repeatedly charge and discharge. PowerBright
TM
recommends using “deep-
cycle” or “marine” rated batteries.