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Battery Size
B–3
Battery Size
Importance Battery size or capacity is as important as the battery type for efficient
operation of your loads. Xantrex recommends that you purchase as much
battery capacity as possible.
Battery
Capacity
Standards
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, either
“amp-hours” (“Ah”) or “reserve capacity” in minutes.
Battery Reserve Capacity Battery reserve capacity is a measure of
how long a battery can deliver a certain amount of current—usually 25
amps. For example, a battery with a reserve capacity of 180 minutes can
deliver 25 amps for 180 minutes before it is completely discharged.
Amp-hour (Ah) Capacity Amp-hour capacity is a measure of how
many amps a battery can deliver for a specified length of time—usually
20 hours. For example, a typical marine or RV battery rated for 100 Ah
can deliver 5 amps for 20 hours (5 A x 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 (for example, 50 A for 2
hours, or 200 A for 1/2 hour), but usually the capacity figure given is only
accurate at the specified rate (20 hours).
To calculate the battery capacity you require, read “Estimating Battery
Requirements” on page B–4 and “Battery Sizing Example” on page B–4,
and then complete the “Battery Sizing Worksheet” on page B–5.
CAUTION
The PROwatt 1000 must only be connected to batteries with a
nominal output voltage of 12 volts. The inverter will not operate from
a 6 volt battery and will be damaged if connected to a 24 volt battery.
PROWatt100.book Page 3 Friday, January 5, 2001 3:03 PM