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Battery Information
Battery Bank Sizing
Battery capacity Battery size or capacity is just as important as the battery type selected for use
with the RS3000. The batteries are the most important part of your system, so
Xantrex recommends that you purchase as much battery capacity as possible. A
large battery will extend running time and ensure that your inverter/charger
delivers full rated surge.
Xantrex recommends a minimum battery size of 200 amp-hours (Ah) for
moderate loads (<1000W) and greater than 400 Ah for heavy loads.
See “Estimating Battery Requirements” below for information on a more detailed
calculation.
About Amp-hours A number of different standards are used to rate battery energy storage capacity.
Automotive and marine starting batteries are normally rated in cranking amps.
This is not a relevant rating for continuous loads like an inverter. Deep-cycle
batteries use a more suitable rating system such as amp-hours (Ah).
Amp-hour capacity is the number of amps a battery can continuously deliver
during a specified number of hours. It is represented by the product of the two —
amps multipled by hours.
A typical marine or RV battery rated for 100 Ah can deliver 5 amps for 20 hours
(5A × 20 hours = 100 Ah). This same battery can deliver a higher or lower current
for less or more time, limited approximately by the 100 Ah figure (50 A for 2
hours or 200 A for 1/2 hour), but usually the capacity figure given is only accurate
for the specified duration (20 hours).
Estimating Battery Requirements
Calculating Battery Size
Step1: Compute
Amp-hours
For each appliance, compute the number of amp-hours that will be used between
charging cycles, as follows:
1. Obtain the wattage. If the wattage is marked on the nameplate rating, use that.
Otherwise, multiply the marked voltage and amperage:
WATTS = VOLTS × AMPS.
2. Obtain the Watt-hours by multiplying that amount by the hours the appliance
will be used:
WATT-HOURS = WATTS × HOURS.
3. Obtain the amp-hours that the appliance requires by dividing that amount by
10 (the factor for the RS3000, which is a 12-volt system):
BATTERY AMP-HOURS USED = AC WATT-HOURS/10
For example, a 100 W light bulb that is used for 4 hours will use 400 watt-hours
(Wh) and the inverter will consume approximately 40 Ah from a 12 volt battery.