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Batteries

CHAPTER. Batteries. 5. Instructor Name: (Your Name ). Objectives. Work safely around batteries Explain the fundamentals of how a lead acid battery produces a voltage Describe the series aiding and series opposing voltage source connection

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Batteries

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  1. CHAPTER Batteries 5 Instructor Name:(Your Name)

  2. Objectives • Work safely around batteries • Explain the fundamentals of how a lead acid battery produces a voltage • Describe the series aiding and series opposing voltage source connection • Explain the process of battery discharging and recharging • Explain how battery internal resistance effects battery terminal voltage

  3. Objectives (continued) • Define typical battery rating such as CCA and reserve capacity • Safely recharge a battery using a battery charger • Test conventional and low maintenance batteries • Jump start a truck using the correct procedures

  4. Objectives (continued) • Service a truck battery box • Describe recombinant batteries • Discuss lithium-ion batteries utilized in hybrid vehicles

  5. WARNING Sulfuric acid is a hazardous substance that can cause blindness and serious chemical burns to the skin. Always wear approved eye protection and protective clothing when handling, charging, servicing, or testing batteries.

  6. Lead Acid Batteries Fundamentals • A battery supplying current to a circuit is said to be discharging • Conventional current flow is from battery positive, through the load and back to battery negative • When a battery receives current flow in the opposite direction of flow it is said to be charging • An alternator is typically used to charge a truck battery

  7. Battery Recharging Figure 5-2 Battery recharging.

  8. Four Main Functions of a Truck Battery • Batteries supply electric current when the truck engine is not running • Batteries supply current to the engine starter motor • Batteries supply current flow when the engine is running and the electrical load exceeds the alternator output. • Batteries stabilize the system electrical system smoothing out voltage spikes

  9. Internal Battery Components • Lead acid batteries are filled with electrolyte which is a mixture of water and sulfuric acid • Battery plates are submerged in the electrolyte • Positive battery plates are constructed of lead peroxide (PbO2) • Negative battery plates are constructed of sponge lead (Pb) • The grid for both negative and positive plates are is usually made of lead calcium

  10. Positive and Negative Battery Plate Figure 5-3 Positive plate and negative plate.

  11. Combining Plate to Form a Cell Figure 5-6 Combining plates to form a cell.

  12. Series and Parallel Voltage Sources • Voltage sources connected in parallel, positive terminal to positive terminal and negative terminal to negative terminal, will assume a common voltage • Voltage sources connected in series, positive terminal to negative terminal will produce a voltage equal to the sum of the individual voltage sources

  13. Battery Cells Connected in Series • 12V truck battery cells are approximately 2.1 volts each • There are 6 cells connected in series • The total voltage for the 6 series connected cells is approximately 12.6 volts

  14. Battery Discharge Chemical Reaction Figure 5-12 Battery discharge chemical action.

  15. Battery Charge Chemical Reaction Figure 5-13 Battery recharging chemical action.

  16. Battery Case and Components Figure 5-14 Case partitions separate cells. Figure 5-15 Assembled battery components.

  17. Battery Terminal Types Figure 5-16 Types of battery terminals: most trucks use stud-type terminals.

  18. Connecting Multiple Batteries • Two 12V batteries connected in parallel, positive to positive and negative to negative, will have 12 volts with higher current • Two 12V batteries connected in series, positive to negative, will have 24 volts with the same current • Two 12V batteries connected in series can be connected in parallel with two more 12V batteries connected in series to get higher current. This is a series-parallel connection.

  19. Internal Resistance of a Battery Figure 5-20 Simple series circuit with two resistors, illustrating battery internal resistance. Figure 5-21 High battery internal resistance.

  20. Cranking Requirements Versus Battery Capacity in Cold Weather Figure 5-24 Engine cranking requirements versus battery current capability in cold weather.

  21. WARNING A battery that is frozen must never be recharged or jump started because it could explode. Batteries must be thawed to room temperature before recharging.

  22. Battery Ratings • Cold Cranking Amps- The amount of current a battery can supply for 30 seconds at 0°f and maintain 1.2V per cell (7.2V for a 12V battery) • Cranking Amps- The amount of current a battery can supply for 30 seconds at 32°f and maintain 1.2V per cell (7.2V for a 12V battery) • Reserve Capacity- the amount of time a battery can supply 25A and not drop below 1.75V per cell (10.5V for a 12V battery)

  23. BCI Group Numbers, Dimensional Specifications, and Ratings Figure 5-27 Sample BCI group number pages.

  24. Battery Recharging • Charging current flow to the battery must be opposite of discharging current flow • Charging voltage must be higher then the battery voltage • Current supplied by a battery for a period of time is expressed in ampere hours • During recharging some electrolyte is converted to hydrogen and oxygen gas • If a battery is charged at too high a current rate it can overheat warping plates, lose excessive amounts of water, and even explode

  25. Current Flow in a Charging Circuit is Opposite of That When a Battery is Discharging Figure 5-28 Direction of current flow passing through a battery to recharge the battery.

  26. Battery Recharging Safety • When a battery is recharging explosive hydrogen gas is given off • Jewelry or tools that make contact between positive and negative posts of a battery can cause severe burns • Gold necklace chains that contact a battery while working can turn molten in a flash and leave a scar • Make sure the AC power cable to charger is properly grounded

  27. Ground Terminal on Battery Charger Power Cable Figure 5-30 Battery charger ground terminal prevents electric shock.

  28. Battery Charger Connection • Always switch off and unplug the charger before making or interrupting any connections at the batteries • Connect the battery charger cables to the battery terminal adaptors • Plug the battery charger into the a wall outlet • Switch the battery charger to the appropriate setting • Reverse the order when disconnecting the battery charger

  29. Battery Testing • Battery specific gravity is the weight of the volume of any liquid compared to an equal volume of water • Electrolyte is a mixture of 36% sulfuric acid to 64% water which equals a specific gravity of 1.256 to 1.280 at 80°F • When specific gravity is measured with a hydrometer it must be compensated for temperature differences above or below 80°F • A refractometer can also be used to measure specific gravity

  30. Measuring Specific Gravity With a Hydrometer Figure 5-32 Drawing electrolyte from a conventional battery.

  31. Specific Gravity Temperature Correction Chart Figure 5-34 Specific gravity temperature correction chart.

  32. Measuring Specific Gravity With a Refractometer Figure 5-36 Optical refractometer. Figure 5-37 Specific gravity measurement with optical refractometer.

  33. Built in Hydrometers • Low loss water batteries do not have access to the cells to test specific gravity • Many low water loss batteries have a built in hydrometer • A built in hydrometer only indicate if the state of charge is above 65% in one cell • Green indicates at least 65% charge • Dark indicates 65% or less charge • Clear indicates low electrolyte level

  34. Built In Hydrometer Figure 5-38 Built-in battery hydrometer.

  35. Surface Charge • A surface charge is hydrogen bubbles that form on the plates of the batteries • These bubbles rapidly dissipate when the battery is discharged • The surface charge causes higher than normal voltage • A nearly discharged battery can appear to be fully charged

  36. Open Circuit Voltage Test Figure 5-39 Open-circuit battery terminal voltage versus state of charge.

  37. Carbon Pile Battery Load Tester Figure 5-40 Carbon pile battery load tester.

  38. Battery Charging and Testing Stud Adaptors Figure 5-41 Battery charging and testing stud adapters.

  39. Temperature Versus Acceptable Load Test Chart Figure 5-42 Temperature versus acceptable load test voltage chart.

  40. Midtronics EXP Battery Tester Figure 5-43 Midtronics EXP Battery test.

  41. Cable Connections For Jump- Starting a Vehicle Figure 5-45 Cable attachment order for jump-starting a 12V truck with another 12V truck.

  42. Battery Connections • Draw diagram, mark, or take digital photo prior to disconnecting batteries • Disconnect first and reconnect last all smaller cables that are attached to the battery connections • Before disconnecting batteries make sure everything on the truck is turned off first • Remove negative cable first • Connect the positive cable first • There will usually always be a small spark when the ground cable is connected

  43. Removing Label to Access Filler Caps on Low-Maintenance Batteries Figure 5-46 Removing label to access filler caps on low-maintenance batteries.

  44. Battery Maintenance Inspection Items Figure 5-47 Battery maintenance inspection items.

  45. Recombination Batteries Figure 5-48 Recombination battery.

  46. Charging Current Decreases as Battery Charges Figure 5-49 Charging current decreases as battery is recharged.

  47. Summary • Batteries store and transform energy. • Batteries are some of the most hazardous components found on trucks. • Lead acid batteries contain two different types of lead along with an electrolyte made of sulfuric acid and water. • The two types of lead are formed into plates. A group of plates are connected in parallel to form a cell. The cells are connected in series. A 12V battery has six cells connected in series. Each cells produces a voltage of about 2.1V.

  48. Summary (continued) • Batteries have internal resistance. The internal resistance varies depending on several factors, including temperature and battery state of charge. Battery internal resistance causes the battery terminal voltage to decrease as the current supplied by the battery increases. • No-load or open circuit voltage refers to the terminal voltage of a battery that is not supplying any current. This no-load voltage can be used to indicate the battery state of charge.

  49. Summary (continued) • There are several battery ratings. CCA indicate how much current a fully charged battery can supply continuously for 30 seconds and still maintain a terminal voltage of 7.2V. Reserve capacity is another rating and indicates how long (in minutes) a battery can supply a 25A load and still maintain a terminal voltage of 10.5V.

  50. Summary (continued) • Batteries are charged by causing a current to flow through the battery. A combination of time and current flow is necessary to recharge a battery. • Specific gravity refers to the weight of electrolyte compared to and equal volume of water. The measurement of specific gravity using a hydrometer can be used to determine a battery state of charge in conventional batteries.

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