Monaco LaPalma Owner's Manual page 324

charge (SOC). Deep cycle batteries should not be cycled below 50% state of
charge. Discharging a deep cycle battery below 50% state of charge shortens the
life of the battery. Deep cycle batteries use an amp hour rating which is usually
calculated over a 20 hour discharge interval. Example: A deep cycle battery with
a rated capacity of 100 Ahr is designed to release current at the rate of five amps
per hour. Multiply a 5 amp load over a 20 hour discharge period equals the rated
100 Ahr capacity. These discharge figures are calculated with the battery starting
at 100% state of charge with the battery at 80º F when the discharge cycle begins.
Increasing the discharge load applied to the battery from five amps to ten amps
on a 100 Ahr battery does not yield 10 hours of discharge time. This is due to the
internal reactions which occur when a battery is discharging. Actual discharge
time for a 10 amp load may be closer to eight hours of discharge time. Increasing
the load applied to the battery to 20 amps will not yield five hours discharge time
but may be less than three hours. It might be understood as a point of diminishing
return.
battery amp hours available is not an equal trade up when voltage is inverted and
amperage is calculated. When the inverter is used to operate an AC load, it uses
approximately ten times the DC current needed from the battery when inverting
12 Volts to operate the 120 Volt item. Also, a small inverter loses approximately
10% of its efficiency when inverting. For example: When using the inverter to
operate an AC electrical item, which has a current draw rating of 2 amps, the
inverter will use over 20 amps DC power from the batteries.
television is rated at 200 watts at 120 Volts. Calculate watts to amps. Divide 200
watts by the operating voltage of 120. This equals 1.6 amps. Multiply 1.6 amps
AC current by a factor of ten the inverter will use. This equals 16 amps DC
battery current. Add the revised 10% efficiency loss figure. This calculates to a
total of 17.6 amps DC. If the battery bank capacity is rated at 500 Ahrs, actual
elapsed time to the suggested 50% state of charge would net viewing time for the
television at approximately 13 hours in ideal conditions.
battery bank when the discharge process begins. Ambient temperature, combined
with other working loads such as lights and parasitic loads applied to batteries,
affect run times. Calculating the exact run time is not precise due to all the
variables and equations involved; however, an approximate time figure can be
obtained. Proper battery maintenance and charge cycles affect battery
performance. Observe the battery condition with hydrometer and voltage
readings. Use only distilled water when filling batteries. To achieve the highest
quality of battery performance and longevity keep batteries in their proper
operating range.
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The working range of a deep cycle battery is between 50 and 100% state of
Calculating applied loads to an inverter to approximate run time from the
Determining Current Consumption:
First determine the amount of current used by an AC item. For example: The
The run time figure will vary greatly with the actual state of charge of the
Electrical Systems
2004 • LaPalma