Holiday 2002 NEPTUNE, Руководство пользователя

Страница: 243 / 344

Electrical Systems - House
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2 0 0 2 N E P T U N E
8 • 243
6. Corrosion:
Corrosion from spilled or splashed electrolyte form deposits that
can conduct electricity and can cause battery drain. Clean off all
corrosion, especially around the battery terminals and on the top of
the battery. Prevent accumulation by coating the terminals and the
exposed metal cable connectors with high temperature grease.
7. Overcharging:
Overcharging rapidly converts water to gas and decreases the elec-
trolyte’s water content as the water evaporates. The electrolyte
level drops and becomes more acid in content. This subjects
the plates to a higher concentration of sulfuric acid and results
in early battery failure.
NOTE: Any time more than one or two ounces of distilled
water is added 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 over-
charging.
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 battery
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. 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 its 15 GPM level, it will
Battery Voltage &
Current