Battery Charge Time & Consumption Rate; Calculating Run Times - Monaco DIPLOMAT 2004 Owner's Manual

DIPLOMAT 2004
Battery Charge Time
& Consumption Rate
8 •320
When the tank is full it is capable of feeding more "pressure" to the pump
inlet due to gravity, and the pump always has enough water available to
maintain its rated pressure and volume. However, if the water tank gets low
the pump will not have enough water volume coming in to maintain 12 psi at 15
GPM. If the loads are removed from the pump by closing the valve on the
outflow, even with low pressure in the tank the pump will eventually pres-
sure up to 12 psi. It will just take it longer to get there. When the valve is
opened the pump will sustain 12 psi for a brief period, but since the tank is no
longer feeding the pump as fast as needed the pressure will eventually drop.
This analogy can be restated by replacing the pump with a battery, pressure
with voltage, volume with amps, outflow valve with a switch, water with electrici-
ty and the water tank with the battery electrolyte.
The level of the tank could be thought of as the rate of the reaction occur-
ring in the electrolyte. When the battery is fully charged the electrolyte has
an excess of reactions taking place to feed the battery terminals. This tapers
off with time as the electrolyte is spent, so maintaining voltage becomes pos-
sible. With no loads, the discharged electrolyte is capable of producing close
to the rated voltage, but only after a period of time has elapsed for enough of
a reaction to take place to bring the voltage back up. This explains why a
battery measured at rest can indicate close to its rated voltage, but will not
run a load.

Calculating Run Times:

Calculating run time figures when operating 120 Volt AC electrical items
with an inverter can be exponential. This is due to battery characteristics.
Flow characteristics of electrons vary with different battery types and
chemical compositions. Deep cycle batteries are generally designed to slow-
ly release a majority of their charge capacity. Deep cycle batteries are rated
in amp hours (Ahrs) with the discharge occurring over an extended period of
time before the battery is charged. Engine starting batteries are designed to
quickly release large amounts of current for short durations, without deplet-
ing battery reserves. Commercial type batteries bridge the gap of deep cycle
and engine batteries. Commercial batteries release medium amounts of cur-
rent over a longer period of time but they are not designed to cycle their
charge capacity.
The working range of a deep cycle battery is between 50 and 100% state
of charge (SOC). Deep cycle batteries should not be cycled below 50% state
of charge. Discharging a deep cycle battery below 50% state of charge short-
ens the life of the battery. Deep cycle batteries use an amp hour rating which
is usually calculated over a 20 hour discharge interval. For example: A deep
cycle battery with a rated capacity of 100 Ahrs. is designed to release current at
the rate of 5 Amps per hour. Multiply a 5 Amp load over a 20 hour discharge
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