2Objectives Work safely around batteries Explain the fundamentals of how a lead acid battery produces a voltageDescribe the series aiding and series opposing voltage source connectionExplain the process of battery discharging and rechargingExplain how battery internal resistance effects battery terminal voltage
3Objectives (continued) Define typical battery rating such as CCA and reserve capacitySafely recharge a battery using a battery chargerTest conventional and low maintenance batteriesJump start a truck using the correct procedures
4Objectives (continued) Service a truck battery boxDescribe recombinant batteriesDiscuss lithium-ion batteries utilized in hybrid vehicles
5WARNINGSulfuric 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.
6Lead Acid Batteries Fundamentals A battery supplying current to a circuit is said to be dischargingConventional current flow is from battery positive, through the load and back to battery negativeWhen a battery receives current flow in the opposite direction of flow it is said to be chargingAn alternator is typically used to charge a truck battery
8Four Main Functions of a Truck Battery Batteries supply electric current when the truck engine is not runningBatteries supply current to the engine starter motorBatteries 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
9Internal Battery Components Lead acid batteries are filled with electrolyte which is a mixture of water and sulfuric acidBattery plates are submerged in the electrolytePositive 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
10Positive and Negative Battery Plate Figure 5-3 Positive plate and negative plate.
11Combining Plate to Form a Cell Figure 5-6 Combining plates to form a cell.
12Series and Parallel Voltage Sources Voltage sources connected in parallel, positive terminal to positive terminal and negative terminal to negative terminal, will assume a common voltageVoltage sources connected in series, positive terminal to negative terminal will produce a voltage equal to the sum of the individual voltage sources
13Battery Cells Connected in Series 12V truck battery cells are approximately 2.1 volts eachThere are 6 cells connected in seriesThe total voltage for the 6 series connected cells is approximately 12.6 volts
14Battery Discharge Chemical Reaction Figure 5-12 Battery discharge chemical action.
15Battery Charge Chemical Reaction Figure 5-13 Battery recharging chemical action.
16Battery Case and Components Figure 5-14 Case partitions separate cells.Figure 5-15 Assembled battery components.
17Battery Terminal Types Figure 5-16 Types of battery terminals: most trucks use stud-type terminals.
18Connecting Multiple Batteries Two 12V batteries connected in parallel, positive to positive and negative to negative, will have 12 volts with higher currentTwo 12V batteries connected in series, positive to negative, will have 24 volts with the same currentTwo 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.
19Internal Resistance of a Battery Figure 5-20 Simple series circuit with two resistors, illustrating battery internal resistance.Figure 5-21 High batteryinternal resistance.
20Cranking Requirements Versus Battery Capacity in Cold Weather Figure 5-24 Engine cranking requirements versus battery current capability in cold weather.
21WARNINGA battery that is frozen must never be recharged or jump started because it could explode. Batteries must be thawed to room temperature before recharging.
22Battery RatingsCold 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)
23BCI Group Numbers, Dimensional Specifications, and Ratings Figure 5-27 Sample BCI group number pages.
24Battery RechargingCharging current flow to the battery must be opposite of discharging current flowCharging voltage must be higher then the battery voltageCurrent supplied by a battery for a period of time is expressed in ampere hoursDuring recharging some electrolyte is converted to hydrogen and oxygen gasIf a battery is charged at too high a current rate it can overheat warping plates, lose excessive amounts of water, and even explode
25Current 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.
26Battery Recharging Safety When a battery is recharging explosive hydrogen gas is given offJewelry or tools that make contact between positive and negative posts of a battery can cause severe burnsGold necklace chains that contact a battery while working can turn molten in a flash and leave a scarMake sure the AC power cable to charger is properly grounded
27Ground Terminal on Battery Charger Power Cable Figure 5-30 Battery charger ground terminal prevents electric shock.
28Battery Charger Connection Always switch off and unplug the charger before making or interrupting any connections at the batteriesConnect the battery charger cables to the battery terminal adaptorsPlug the battery charger into the a wall outletSwitch the battery charger to the appropriate settingReverse the order when disconnecting the battery charger
29Battery TestingBattery specific gravity is the weight of the volume of any liquid compared to an equal volume of waterElectrolyte is a mixture of 36% sulfuric acid to 64% water which equals a specific gravity of to at 80°FWhen specific gravity is measured with a hydrometer it must be compensated for temperature differences above or below 80°FA refractometer can also be used to measure specific gravity
30Measuring Specific Gravity With a Hydrometer Figure 5-32 Drawing electrolyte from a conventional battery.
31Specific Gravity Temperature Correction Chart Figure 5-34 Specific gravity temperature correction chart.
32Measuring Specific Gravity With a Refractometer Figure 5-36 Optical refractometer.Figure 5-37 Specific gravity measurement with optical refractometer.
33Built in HydrometersLow loss water batteries do not have access to the cells to test specific gravityMany low water loss batteries have a built in hydrometerA built in hydrometer only indicate if the state of charge is above 65% in one cellGreen indicates at least 65% chargeDark indicates 65% or less chargeClear indicates low electrolyte level
34Built In HydrometerFigure 5-38 Built-in battery hydrometer.
35Surface ChargeA surface charge is hydrogen bubbles that form on the plates of the batteriesThese bubbles rapidly dissipate when the battery is dischargedThe surface charge causes higher than normal voltageA nearly discharged battery can appear to be fully charged
36Open Circuit Voltage Test Figure 5-39 Open-circuit battery terminal voltage versus state of charge.
41Cable Connections For Jump- Starting a Vehicle Figure 5-45 Cable attachment order for jump-starting a 12V truck with another 12V truck.
42Battery ConnectionsDraw diagram, mark, or take digital photo prior to disconnecting batteriesDisconnect first and reconnect last all smaller cables that are attached to the battery connectionsBefore disconnecting batteries make sure everything on the truck is turned off firstRemove negative cable firstConnect the positive cable firstThere will usually always be a small spark when the ground cable is connected
43Removing Label to Access Filler Caps on Low-Maintenance Batteries Figure 5-46 Removing label to access filler caps on low-maintenance batteries.
46Charging Current Decreases as Battery Charges Figure 5-49 Charging current decreases as battery is recharged.
47Summary 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.
48Summary (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.
49Summary (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.
50Summary (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.
51Summary (continued)Surface charge refers to gas bubbles on the plates that can make a battery appear to be at a higher state of charge than it actually is. Surface charge must be removed before testing a battery.A carbon pile tester is used to load test a battery.