Electrical Information
Vehicle
Page3-2
Crestline
Manual
9/20/2007
Coach
Charging/Electrical Systems
There are five components common to the electrical charging circuits of eachmodel of ambulance
built byCrestline.
These items are:
1)O.E.M factorybattery
2)Dedicated conversionbattery
3)Highoutput alternator
4)Battery isolator
5) Fast idle throttle control
On all Ford chassis, only diesel engines are approved for ambulance usage. Thus, the Ford
ambulance preparation package includes dual factory batteries, and dual factory installed 110 amp
alternators. On 2004 and newer Ford chassis’, bothOEM batteries comemounted to the passenger
side frame rail andCrestline installs them in the stepwell of the conversion frame. The ambulance
batteryandbattery isolator are supplied and installedbyCrestline.
FactoryBatterySystem
TheO.E.M. factorybattery systemprovides power to the factorycircuits and accessories only. This
includes the headlights, instrument cluster, signal lamps, engine electrical circuits, etc. Since this
battery is the primary power source for starting the engine, it is essential to connect the voltage
regulator to this battery. Thus the regulator ensures that the alternator supplies enough current to
maintain a fully charged factory battery for ease of starting. This is the case regardless of whether
the alternator is installedby the chassismanufacturer or byCrestline.
To ensure satisfactorybatteryperformance, battery terminal cleanliness is essential.
DedicatedConversionBattery
The ambulance battery is typically installed in an exterior compartment on the left hand side of a
modular ambulance body. This batteryprovides power to all conversion circuits. This includes all
warning lights, sirens, patient compartment lights, heater andA/C, etc. Since the current drain due
to the ambulance load is often prolonged, the ambulance battery is aDeepCycleR.V typematched
to this type of load. The alternator provides charging current to this battery through the battery
isolator; thevoltage is regulated to the same level as that on the factorybattery.
HighOutputAlternator
The Ford ambulance prep package comes completewith two 110-ampOEM alternators. These are
necessary to supply the large current demand of a modern ambulance. The alternator must have
enough capacity at high operating temperatures tomeet or exceed the entire electrical load imposed
byan emergency response situation.
To ensure satisfactory alternator operation, it is essential to check the alternator belts frequently for
correct tension.
