CAUTION! INVERTER's must be connected only
to batteries with the corect output voltage
The 12 volt INVERTER must be connected only to a 12 volt battery
system
The 24 volt INVERTER must be connected
only to a 24 volt battery system.
Battery Sizing
There are a number of different standards for rating battery
energy storage capacity. Automotive starting batteries are normally
rated by cranking amps. This is not a relevant rating, for continuous
use. Deepcycle batteries are rated either by reserve capacity in
minutes or by amperehour capacity.
Battery reserve capacity is a measure of how long
a battery can deliver a certain amount of current  usually 25 amperes.
For instance, a battery with a reserve capacity of 180 minutes can
deliver 25 amperes for 180 minutes before it is completely discharged.
Amperehour capacity is a measure of how many amperes
a battery can deliver for a specified length of time usually 20
hours. For example, a typical marine or RV battery rated for 100
amperehours can deliver 5 amperes for 20 hours (5 amperes x 20
hours = 100 amphrs).
Actual battery capacity decreases as discharge current
increases. A battery rated at 100 amperehours which can deliver
5 amperes for 20 hours, may deliver 20 amperes for only 4 hours,
resulting in an actual capacity of 80 amperehours. For this reason,
it is difficult to compare rated amperehour capacity with battery
reserve capacity. For example a battery with a reserve capacity
of 180 minutes has the following calculated ampere hour capacity
180 min. Divided by 60 = 3 hr., 3 hr. x 25 amps =
75 amphrs
However its actual amperehour rating will be closer to 100 amperehours
because it is rated at the discharge current required to get 20
hours of operation (about 5 amperes).
To determine the battery capacity you require,
follow these steps:
STEP 1 For each piece of equipment you will be operating
from 2500W INVERTER, determine how many watts it consumes. This
can normally be found on a label on the product. If only the current
draw is given, multiply the current draw by 115 (or 225) to get
the power consumption in watts.
STEP 2 For each piece of equipment you will be operating
from 2500W INVERTER, estimate how many hours it will operate between
battery charging cycles.
STEP 3  Calculate total watthours of energy consumption,
total hours running time, and average power consumption as in the
following example.
STEP 4  Using the chart below (Table 3 ), find the battery
size that will give you the required operating time at the calculated
average power consumption. For instance, from the example below,
the required operating time is 6 hours and the average power consumption
is 387 watts. From the chart, the smallest battery size which will
give more than 6 hours of operation at a power level between 300
and 400 watts are two 400 amphr. batteries in parallel, which offers
between 10 and 12 hours of operating time.
