Section 8
--- Electrical Systems - House
The Executive 2005
368
Battery Voltage & Current
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 pres-
sure. 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
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 buck-
et. 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 possi-
ble. 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.
Summary of Contents for Executive 2005
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Page 30: ...Section 1 General Information The Executive 2005 30 NOTES...
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Page 92: ...Section 2 Driving Safety The Executive 2005 92 Weight Label 100179D...
Page 98: ...Section 2 Driving Safety The Executive 2005 98 020254...
Page 101: ...Driving Safety Section 2 The Executive 2005 101 020263 WEIGHT RECORD SHEET 020262...
Page 102: ...Section 2 Driving Safety The Executive 2005 102 WEIGHT RECORD SHEET 020262...
Page 103: ...Driving Safety Section 2 The Executive 2005 103 010763d 010689d VIEWS Front Rear...
Page 104: ...Section 2 Driving Safety The Executive 2005 104 010687e 010688c Roadside Curbside...
Page 119: ...Driving Safety Section 2 The Executive 2005 119 NOTES...
Page 120: ...NOTES 120 The Executive 2005 Section 2 Driving Safety...
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Page 132: ...Section 3 Exterior Interior Care The Executive 2005 132 Fabric Specifications Charts...
Page 133: ...Exterior Interior Care Section 3 The Executive 2005 133...
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Page 135: ...Exterior Interior Care Section 3 The Executive 2005 135...
Page 136: ...Section 3 Exterior Interior Care The Executive 2005 136 Ralph Lauren Fabrics Optional Package...
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Page 204: ...Section 4 Appliances The Executive 2005 204 NOTES...
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Page 264: ...Section 5 Equipment The Executive 2005 264 NOTES...
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Page 299: ...Water Systems Section 6 The Executive 2005 299 TYPICAL WATER BAY 040496c...
Page 301: ...Water Systems Section 6 The Executive 2005 301 NOTES...
Page 302: ...Section 6 Water Systems The Executive 2005 302 NOTES...
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Page 321: ...LP Gas Systems Section 7 The Executive 2005 321 NOTES...
Page 322: ...Section 7 LP Gas Systems The Executive 2005 322 NOTES...
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Page 380: ...Section 8 Electrical Systems House The Executive 2005 380 Wiring Systems Interfaced...
Page 381: ...Electrical Systems House Section 8 The Executive 2005 381 NOTES...
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Page 419: ...Electrical Systems Chassis Section 9 The Executive 2005 419 ENGINE NO START FLOW CHART...
Page 420: ...Section 9 Electrical Systems Chassis The Executive 2005 420 NOTES...
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Page 523: ...Chassis Information Section 10 The Executive 2005 523 METRIC U S CONVERSION CHART...
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Page 529: ...The Executive 2005 Index...
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Page 538: ...Index The Executive 2005 538 NOTES...