Battery Charge Time & Consumption Rate - Holiday Navigator 2003 Owner's Manual

finite capacity will start to lose the ability to hold pressure as the level of water
in the tank drops. Think of siphoning water from a bucket. As the level of the
water drops, the volume of water exiting the siphon slows down.
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 pressure
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 electricity
and the water tank with the battery electrolyte.
The level of the tank could be thought of as the rate of the reaction occurring
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 possible.
With no loads the discharged electrolyte will be 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. Hopefully, this explanation
will clarify 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 slowly 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 depleting battery
reserves. Commercial type batteries bridge the gap of deep cycle and engine
batteries. Commercial batteries release medium amounts of current 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 shortens
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
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Electrical Systems - House
Battery Charge Time
& Consumption Rate
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