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Truck Trailer Refrigeration Electrical Components

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Presentation on theme: "Truck Trailer Refrigeration Electrical Components"— Presentation transcript:

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

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