1. Truck Trailer Refrigeration Electrical Components
CHAPTER 16
Truck Trailer Refrigeration Electrical Components
Instructor Name: (Your Name)

2. Learning Objectives Describe the construction of storage batteries
Work safely around storage batteries
Explain the two different ways in which batteries may be shipped from the manufacturer
Describe the three different types of batteries used today and how maintenance is performed on them
Explain how batteries are rated
Describe storage procedures for batteries
Explain testing procedure to ensure batteries can perform to rated performance level

3. Learning Objectives (continued)
Describe how a battery should be charged and list the steps involved in jump-starting a unit with a low battery
List the steps in removing and replacing a battery
Explain the function of the charging system
List the major components of a typical alternator and the function of the parts
Explain the function of a voltage regulator
Describe the steps of an alternator output test

4. Learning Objectives (continued)
List the steps involved in removing and replacing an alternator
Describe the two styles of starters used in the transportation refrigeration industry
Explain the purpose of an overrunning clutch
Describe the steps involved in performing a starter test
Explain the purpose of the various truck refrigeration safety switches

5. Battery Construction
Case filled with diluted solution of sulfuric acid and water
Positive and negative electrodes in the form of plates
Plates composed of lead or lead derived material
Batteries are divided into several cells, 6 cells for a 12 volt battery

6. Typical Battery

7. Cell Operation
When two dissimilar metals are placed in an acid bath, an electrical potential is produced across the poles
Voltage is produced due to a reaction between the plates and the electrolyte
The positive plate is composed of lead peroxide
The negative plate is composed of sponge lead
Electrolyte is a solution of water and sulfuric acid

8. Cell Operation (continued)
Six cell elements in a 12 volt battery
Each cell produces approximately 2.1 volts regardless of size and number of plates
Cells are connected in series to produce 12.6 volts

9. Single Battery Cell

10. Battery With Six Cells

11. Battery Safety
Keep flames and sparks away form batteries, do not smoke near batteries
Wear eye protection and rubber gloves to protect from chemical burns
Never connect or disconnect live circuits. Always turn off unit, battery charger or tester when attaching or removing leads
Batteries should always be installed in a vented battery box to vent hydrogen gas while charging

12. Battery Safety (continued)
Work in a well vented area when charging batteries
Always keep the battery upright to prevent spilling electrolyte
Never work alone on batteries, in case of accident

13. CAUTION
Battery electrolyte contains sulfuric acid, which can cause severe personal injuries (burns) and damage to clothing and equipment. If electrolyte is spilled or splashed on a person’s body or clothing, it must be immediately neutralized by washing with a solution of baking soda and water. The solution should be 0.25 pounds baking soda to 1 quart of water. Electrolyte splashed into the eyes is extremely hazardous. The eyes should be immediately held open and flushed with cool clean water for about 5 minutes, then seek medical treatment at once.

14. Battery Types; Conventional
Require the most maintenance
Water in electrolyte turns to a gas and must be replenished
Use only distilled water when filling a battery
Water level should be no higher than 1/8” (3.2 mm) below vent well
Damage can occur if electrolyte level drops below top of cell plates
Over filling can weaken electrolyte solution and battery

15. Battery Types; Conventional (continued)
Vaporized electrolyte can condense on top of case and discharge battery
Vaporized electrolyte can condense on top of case and corrode terminal and cables
Conventional batteries are easily overcharged
Conventional batteries perform well in a deep cycle application

16. Correct Electrolyte Level

17. Low Maintenance Batteries
Less maintenance then conventional batteries
Less electrolyte gasification
Less corrosion of terminals
More resilient to over charging
Shorter life in a deep cycle application

18. Maintenance Free Batteries
Designed to not require electrolyte replenishment under normal operating conditions
Terminal and cable ends almost maintenance free
Generally require higher voltage regulator settings then conventional and low maintenance batteries

19. Battery Ratings CCA
Performance rated by their cold cranking amps (CCA) designation
Load in amperes a battery can sustain for 30 0⁰ F (-17.8⁰ C) and not fall below 1.2 v per cell or 7.2 v on a 12 v battery
CCA indicates how much power a battery can deliver in extremely cold conditions

20. Cold Weather Effects on Battery

21. Battery Ratings; Reserve Capacity
The number of minutes a new fully charged battery at 80⁰F (26.6⁰C) can sustain a load at 25 amperes before battery voltage drops to 1.75 V per cell or 10.5 V for a 12 V battery.
Reserve capacity indicates how long a battery can provide enough power to keep ignition, head and tail lights, windshield wipers, and heater operating if charging system fails

22. Battery Rating; BCI Number
Battery Council International (BCI) a number indicates batteries physical dimensions
BCI number indicates the height, width, and length
BCI number is no indication of the batteries performance capacity
A batteries performance characteristic is determined by internal components

23. BCI Battery Dimensions

24. Battery Maintenance Check for loose terminals
Check for cracked or broken case
If case is broken replace immediately
Inspect case for dirt, moisture, and corrosion
Clean case and terminals with baking soda
Battery cable should be checked for cleanliness and tightness
Check electrolyte level, add water if low
Note: Even maintenance free batteries electrolyte levels should be checked monthly

25. Hydrometer Testing
Hydrometer tests the state of charge by measuring the specific gravity of electrolyte
A fully charged battery will have a specific gravity of at 80⁰F (26.7⁰C)
A hydrometer must be temperature compensated, add .004 for every 10⁰ above 80⁰F and subtract .004 for every 10⁰ below 80⁰F

26. Hydrometer Reading

27. Refractometer Testing
No temperature compensation needed
Wear eye protection when using refractometer
Extract a drop of electrolyte, place on lens of refractometer
Hold meter up to light and view readings
Electrolyte Reading
Reading % Charge

28. Open Circuit Voltage Test
Determines battery state of charge
Performed when battery is at rest, no load
Remove surface charge prior to test
Meter Reading Battery Condition
Fully Charged
% Charge
% Charge
% Charge

29. Battery Load Test
Load test gives true measurement of a batteries ability to perform
Battery must be fully charged
Load to 50% of rated CCA
Hold load for 15 seconds
Battery voltage should not drop below 9.6V at 70⁰F (21⁰C )
Replace battery if it falls below minimum specifications

30. Jump Starting
Connect to positive terminal of stalled battery
Connect to positive terminal of jumper battery
Connect to negative terminal of jumper battery
Connect to good chassis ground on stalled vehicle away form batteries
Disconnect jump cable exact reverse order used to connect them

31. Alternator Components
Stator
Three individual windings in a ring made of iron
Electrical impulses occur at different times to produce three phase current
Rotor
Rotating magnet that spins inside the stator
Wire coil between two interlocking iron sections mounted on a shaft
Each lobe is a north or south magnetic pole
Rotor is magnetized only when current is applied through slip rings and brushes

32. Alternator

33. Rotor and Stator

34. Alternator Components (continued)
Rectifier Diodes
Alternator produces alternating current
Rectifier diodes changes alternating current to direct current
Field diodes are used to separate field circuit from rectifier circuit
Voltage Regulator
Voltage regulator performs two tasks
Regulator excites the field coil
Regulator regulates the output voltage of the alternator to a set safe value during charging

35. Alternator Output Test
Output test checks alternators ability to deliver rated output of voltage and current
Performed if unit is over or under charging
Run unit at high speed
Adjust load to highest current with out dropping voltage below 12 volts
Read ammeter, reading should be with in 10% of the alternators rated output capacity
Always follow the load tester manufactures instructions when testing an alternators output

36. Alternator Removal and Installation
Always disconnect battery first
Identify positive an negative terminal before hooking up, reversed polarity can destroy rectifier diodes
Alternator belt should wrap around pulley a minimum of 100 degrees and be 90 degrees with face of pulley
Check belt tension by consulting the maintenance manual
If charging the battery on the unit, disconnect the positive cable to prevent damage to the alternator or voltage regulator

37. Alternator Installation
Belt to Pulley Alignment
Belt Engagement in Pulley

38. Starters
Two styles used in transportation refrigeration, conventional and gear reduction
Conventional starter pinion gear mounted on the motor armature
Conventional starter uses solenoid to pull plunger and lever to move pinion gear into mesh with ring gear
Gear reduction starter uses smaller high speed motor
Gear reduction pinion gear turn at 1/4 to 1/3 motor speed
Gear reduction solenoid acts directly on reduction gear and pinion gear
Overrunning clutch prevent damage to pinion gear once engine starts

39. Conventional Starter

40. Gear Reduction Starter

41. Overrunning Clutch

42. Starter Testing
Starter amp draw test ensures starter is in good condition
Starter amp draw test also test condition of batteries
Ensure batteries are in good condition and at a minimum of 50% charge
Use a suitable amp meter on the batteries
Disable the engine from starting during test
Crank engine and watch current draw
Cranking speed should be normal and current draw should not exceed manufacturers specification
Always follow the manufacturers recommendations for this test

43. Safety Switches
Low oil pressure cut out switch protects engine in the event of low or loss of oil
Installed in the oil galley of the engine
Engine shuts down if oil pressure drops below 15 psi
High engine coolant temperature switch is normally located in the cylinder head water passages
If engine coolant temperature rises to a preset point the bimetal switch contacts open circuit causing engine to shut down
Newer style can be an electronic switch that sends signal to the engines microprocessor

44. Low Oil Pressure and High Engine Temperature Switches

45. Safety Switches (continued)
High compressor discharge switch may be mounted in compressor cylinder head, discharge manifold, or line between compressor and condenser
High compressor switch will shut down engine if a preset discharge pressure is reached
Low compressor oil pressure switch shuts unit down in the event of loss of oil pressure in the compressor

46. High Pressure Cut Off Switch

47. Summary
Transport refrigeration equipment uses 12 automotive type storage batteries
Batteries work on principle that when two dissimilar metals in acid bath, and electrical potential is produced
Each cell of a battery produces 2.1 volt
12 V batteries use 6 cells connected in series
Always follow safety precautions when working around batteries
Batteries may be shipped from manufacturer as wet charged or dry charged

48. Summary (continued)
There are three classifications of batteries, conventional, low maintenance, and maintenance free
Batteries are rated by BCI rating, CCA rating, or reserve capacity
Batteries should be stored in a clean dry environment between 50⁰F and 60⁰F (10⁰C and 16⁰C)
Batteries can be tested by open circuit test, specific gravity and load test
If a battery has been discharged fast it should be charged fast, if it has been discharged slow it should be charged slow

49. Summary (continued)
Jump starting a vehicle is performed when the units battery is low and the unit must run. The battery will require maintenance as soon as possible
The charging system is responsible for recharging battery once unit is running and providing current for system loads
The rectifier converts alternating current to direct current
The voltage regulator controls alternator output voltage within a safe limit, as specified by equipment manufacture

50. Summary (continued)
An alternator output test confirms how many amps the alternator can produce when fully loaded, in comparison to rated output
Starters for refrigeration units fall into two different categories, conventional starters and gear reduction starters
An overrunning clutch protects the starter from excessive engine rpm by disengaging the pinion gear from the armature of the starter

51. Summary (continued)
Starters are tested by measuring the number of amps they draw when starting the engine, in comparison to the starters rated draw
Safety switches protect people from any personal injury as well as protect the unit from physical damage caused by running a unit under abnormal conditions