Electrical Information
Vehicle
Page 3-2
Crestline
Manual
1/11/2006
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, onlydiesel engines are approved for ambulance usage. Thus, theFord ambulance
preparation package includes dual factory batteries, and dual factory installed 110 amp alternators.
On 2004 and newer Ford chassis', both OEM batteries come mounted to the passenger side frame
rail and Crestline installs them in the step well of the conversion frame. The ambulance battery
andbattery isolator are suppliedand installedbyCrestline.
FactoryBatterySystem
The O.E.M. factory battery system provides power to the factory circuits 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 toconnect thevoltage 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 thechassismanufacturer or byCrestline.
To ensure satisfactorybatteryperformance, battery terminal cleanliness is essential.
DedicatedConversionBattery
Theambulancebattery is typically installed inanexterior compartment on the left hand sideof amodular
ambulancebody. Thisbatteryprovidespower toall conversioncircuits. This includes allwarning 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; the voltage is
regulated to the same level as that on the factorybattery.
HighOutputAlternator
The Ford ambulance prep package comes complete with two 110-ampOEM alternators. These are
necessary to supply the largecurrent demandof amodernambulance. Thealternatormust haveenough
capacity at high operating temperatures to meet or exceed the entire electrical load imposed by an
emergency response situation.
To ensure satisfactory alternator operation, it is essential to check the alternator belts frequently for
correct tension.
Battery Isolator
Thebattery isolator,which is located in the ElectricalControlCentre, allows thealternator tocharge the
