DHC BT2400 Manuel De L'utilisateur page 21

What is CCA (COLD CRANKING AMPS)?
The current in amperes which a new fully charged battery can deliver for 30
seconds continuously without the terminal voltage falling below 1.2volts per cell,
after it has been cooled to 0OF and held at that temperature. This rating reflects
the ability of the battery to deliver engine starting currents under winter conditions.
What is AMPERE-HOUR?
The unit of measurement of electrical capacity. A current of one ampere for one
hour implies the delivery or receipt of one ampere-hour of electricity. Current
multiplied by time in hours equals ampere-hours.
What is Cylinder Compression Ratio?
Correct functioning of the engine depends on many factors like correct sensor
readings and proper functioning actuators. The Engine itself also needs to be in
good condition.
It is essential to the running of the engine that it has sufficient compression.
The compression provided by the rising piston is determined by the ratio of two
volumes: the volume swept by the cylinder as it compresses, and the volume
remaining in the combustion chamber at top-dead-center. This ratio is called the
compression ratio.
The compression is also determined by the effectiveness of the seal between the
cylinder's wall and the piston, and this seal is maintained by the piston rings.
The same applies to the seating of both the inlet and exhaust valves. Piston rings
are made of centrifugally spun cast iron, which produces a radial pressure
forming the seal. Cast iron is also used for its excellent self-lubricating properties.
Compression Ratio = Cylinder Volume divided by Chamber Volume.
A typical compression is between 120 and 200 psi.
What could cause a low cylinder compression?
1. An ineffective seal between the cylinder and the piston.
2. Poor seating of the inlet and exhaust valves.
3. Broken or seized piston rings.
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