Monaco SIGNATURE 2001 series, Owner'S Manual

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NOTE: Any time you add more than one or two ounces
of distilled water per-cell per-thousand miles, check the
motorhome charging system for overcharging. Prolonged
overcharging generates excessive heat inside the battery,
which buckles the plates and destroys the battery. It is a fact
that over 50% of battery failures are caused by overcharging.
Why does the voltage on a discharged battery measure the same as a fully
charged battery until the loads are applied? The simple answer to this might
go as follows: A battery creates electrical power by converting energy from a
chemical reaction into electrical energy. As this reaction slows down the bat-
tery voltage will drop. In a lead acid battery the electrolyte conductivity (how
well electrical current can flow through it) changes. The same current may be
available but the rate of the reaction decreases, causing a voltage drop.
Another way of looking at this is to use the analogy of a water pump
(a battery is an electric pump). The pressure in PSI (pounds per square inch)
that a pump delivers is like a battery’s voltage. The volume of water in GPM
(gallons per minute) is like the electrical current. Let’s look at a 12 PSI pump
with no loads (the pump is running but the outflow valve is turned off). The
pump will run and the internal pressure of the pump will build up to some
point higher than 12 PSI. When the valve is opened, and the water is free to
flow into the loads, the pressure will drop to the rated output pressure of 12
PSI, but only if the load is not too big. If the pump is designed to maintain
12 PSI at 15 GPM, and a load demanding 20 GPM is connected, the pump
will not be able to keep up and the pressure will get sucked down to a lower
PSI. If the load is reduced or removed the pump will catch up and return to
its rated 12 PSI pressure. If the pump has an infinite source of water, such as
a lake or the water utility (this is like the grid, no battery), the pump will
never run out of pressure. If the pump never runs out of pressure, and is
operated at or below it’s 15 GPM level, it will hold 12 PSI. However, a pump
that is connected to a water tank with a 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,
Electrical Systems - House
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S I G N A T U R E 8 • 2 1 6
Battery Voltage &
Current