Battery bank, Planning – Outback Power Systems GS4048A Installation Manual User Manual
Page 9
Planning
7
Battery Bank
When planning a battery bank, consider the following:
Cables: Recommendations for battery cable size and length are shown on page 20. The maximum length
will determine the placement of the battery bank. Other local codes or regulations may apply and may take
priority over OutBack recommendations.
Battery Type: The Radian inverter/charger uses a three-stage charge cycle.
~ The cycle was designed for lead-chemistry batteries intended for deep discharge. These include
batteries for marine, golf-cart, and forklift applications. They also include gel-cell batteries and
absorbed glass-mat (AGM) batteries. OutBack Power recommends the use of batteries designed
specifically for renewable energy applications. Automotive batteries are strongly discouraged and will
have a short life if used in inverter applications.
~ Each stage of the charging cycle can be reconfigured or omitted from the cycle if necessary.
This programming is performed using the system display. The charger can be customized to charge a
wide range of battery technologies including nickel, lithium-ion, and sodium-sulfur batteries.
~ The Radian inverter/charger is designed to work with a 48-volt battery bank. Before constructing a
battery bank, confirm the nominal voltage of individual batteries.
Charger Settings and Maintenance: A vented battery enclosure may be required by electric code and is
usually recommended for safety reasons.
It may be necessary to use a fan to ventilate the battery enclosure.
Batteries must be regularly maintained according to the instructions of the battery manufacturer.
Bank Size: Battery bank capacity is measured in amp-hours. Determine the required bank specifications as
accurately as possible, beginning with the items below. This avoids underperformance or wasted capacity.
These ten items are obtainable in different places, summarized in Table 2 on the next page. Some of the
information is specific to the site or application. Some can be obtained from the battery manufacturer.
Information on OutBack products is available from OutBack Power Technologies or its dealers.
A. Size of load:
B. Daily hours of use:
C. Days of autonomy:
D. Application: This often helps define or prioritize the previous three items. Off-grid systems often
require enough capacity to last for an extended period before recharging. Grid-connected systems
frequently need only enough capacity for short-term backup during outages.
E. Conductor efficiency: Wire size and other factors
will waste power due to resistance and voltage drop.
Typical acceptable efficiency is 96 to 99%.
F. Inverter efficiency: Radian specifications list
“Typical Efficiency” to help estimate operating loss.
IMPORTANT:
Battery charger settings need to be correct for a given battery type. Always follow
battery manufacturer recommendations. Making incorrect settings, or leaving them at
factory default settings, may cause the batteries to be undercharged or overcharged.
CAUTION: Hazard to Equipment
Batteries can emit vapors which are corrosive over long periods of time. Installing the
inverter in the battery compartment may cause corrosion which is not covered by the
product warranty. (Sealed batteries may be an exception.)
Any losses are essentially amp-hour
capacity that the system cannot use.
The battery bank size can be
increased to account for losses.
These are the most basic
and essential factors used
to determine bank size.