start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 39, the reader should be able to: • • • • Describe how a battery works List the precautions necessary whenever working with batteries Explain how to safely charge a battery Discuss how to perform a battery drain test Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: absorbed glass mat (AGM) battery • ampere-hour (Ah) rating • antimony battery electrical drain test • BCI calcium • cells • cold-cranking amperes (CCA) • conductance testing • cranking amperes (CA) deep cycling • dynamic voltage electrolyte • element flooded cell battery Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: gassing • gell battery • grids ignition off draw (IOD) test jump-starting lead dioxide (peroxide) • lead sulfate • load test • lowwater-loss battery maintenance-free battery • marine cranking amperes (MCA) • meniscus open circuit battery voltage test Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: parasitic load test • partitions • pasting • porous lead radial-grid design • recombinant design battery • reserve capacity (RC) sealed lead-acid (SLA) battery • sealed valve regulated (SVR) battery • sediment chamber • separators • specific gravity • sponge lead valve regulated lead-acid (VRLA) battery Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Everything electrical in a vehicle receives its current from the battery The battery is one of the most important parts of a vehicle and is the foundation for the entire electrical system Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PURPOSE OF A BATTERY The primary purpose of an automotive battery is to provide a  source of electrical power for starting and for electrical demands  that exceed generator output.  The battery is a voltage stabilizer because it acts as a reservoir  where large amounts of current (amperes) can be removed quickly  during starting and replaced gradually by the generator during  charging The battery must be in good (serviceable) condition before the  charging system and the cranking system can be tested. It is  important to test the vehicle battery before further testing of the  cranking or charging system Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 BATTERY CONSTRUCTION Most automotive battery cases (container or covers) are constructed  of polypropylene, a thin (approx. 0.08 inch [.0 millimeters] thick),  strong, and lightweight plastic. Industrial and truck batteries are  constructed of a hard, thick, rubber material Inside the case are six cells (for 12­volt), each  with positive and negative plates. Built in the  bottom are ribs to support the lead­alloy plates  and provide space for sediment to settle.  Figure 39–1 Batteries are constructed of plates grouped into cells, installed in a plastic case This sediment chamber, prevents spent  material from causing a short circuit between  the plates at the bottom of the battery.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 GRIDS Each positive and negative plate in a battery is constructed on a  framework or grid of lead. Lead is soft and must be strengthened  by adding antimony or calcium for battery use. Grids hold the  active material and provide electrical pathways for the current  created in the plate Maintenance­Free versus Standard Battery Grids  A normal  battery uses up to 5% antimony in the plate grids to add strength.  The more amount of antimony, the more gassing (hydrogen and  oxygen gases released), and the more water the battery will use Maintenance­free batteries use calcium instead of antimony,  because 0.2% calcium has the same strength as 6% antimony.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Low­maintenance batteries use a low percentage of antimony (about  2% to 3%) or antimony only in positive plates and calcium for  negative plates The percentages that make up the alloy of the plate grids constitute  the major difference between standard and maintenance­free  batteries. Chemical reactions inside each battery are identical  regardless of type of grid material used Radial­Grid Design  Some batteries use a grid design with only  vertical and horizontal strips. The battery plate creates electricity  from chemical energy, and this current must flow from where it is  generated to where it connects to the outside battery post The current must move over and up along the grid strips Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 It Could Happen To You! - Part of Figure 39–27(b) A schematic drawing of the same memory saver Some experts recommend using a 12-volt lantern battery instead of a small 9-volt battery to help ensure that there will be enough voltage in the event that a door is opened while the vehicle battery is disconnected Interior lights could quickly drain a small 9volt battery Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 BATTERY ELECTRICAL DRAIN TEST The battery electrical drain test determines if some component or  circuit in a vehicle is causing a drain on the battery when  everything is off. This test is also called the ignition off draw  (IOD) or parasitic load test. This test should be performed  whenever one of the following conditions exists: Whenever a battery is being charged or replaced (a battery  drain could have been the cause for charging or replacing  the battery) Whenever the battery is suspected of being drained  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PROCEDURE FOR BATTERY ELECTRICAL DRAIN TEST The fastest and easiest method to measure battery electrical drain is  to connect an inductive DC ammeter that is capable of measuring  low current (10 mA). Here is an example of a clamp­on digital  multimeter being used to measure battery drain.  Figure 39–28 This mini clamp-on digital multimeter is being used to measure the amount of battery electrical drain that is present In this case, a reading of 20 mA (displayed on the meter as 00.02A) is within the normal range of 20 to 30 mA Be sure to clamp around all of the positive battery cable or all of the negative battery cable, whichever is easiest to get the clamp around Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Procedure for battery electrical drain test using a test light: Make certain that all lights, accessories, and ignition are off Check all vehicle doors to be certain that the interior  courtesy (dome) lights are off Disconnect the negative () battery cable and install a parasitic load tool as shown here Start the engine, drive vehicle about 10 min, using lights, accessories and radio Figure 39–29 After connecting the shutoff tool, start the engine and operate all accessories Stop the engine and turn off everything Connect the ammeter across the shutoff switch in parallel Wait 20 minutes This time allows all electronic circuits to “time out” or shut down Open the switch— all current now will flow through the ammeter A reading greater than specified (usually greater than 50 milliamperes [0.05 amperes]) indicates a problem that should be corrected Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Turn off the engine and all accessories including the under­hood  light Connect an ammeter across the parasitic load tool switch and  wait 10 minutes for all computers and circuits to shut down Open the switch on the load tool and read the battery electrical  drain on the meter display Results: Normal—10 to 30 mA (0.02 to 0.03 A) Maximum allowable—50 mA (0.05 A) CAUTION: Using a voltmeter to measure battery drain is not  recommended by most vehicle manufacturers. The high internal resistance  of the voltmeter results in an irrelevant reading that does not provide the  technician with adequate information about a problem Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Be sure to reset the clock and antitheft radio if equipped.  Figure 39–30 The battery was replaced in this Acura and the radio displayed “code” when the replacement battery was installed Thankfully, the owner had the five-digit code required to unlock the radio Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: Many electronic components draw a continuous, slight amount of  battery current the ignition is off. These components include: Digital clocks Electronically tuned radios for station memory and clock circuits  (if the vehicle is so equipped) The engine control computer (if the vehicle is so equipped), through  slight diode leakage The generator (alternator), through slight diode leakage.  These components may cause a voltmeter to read full battery voltage if it is  connected between the negative battery terminal and the removed end of the negative battery cable Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 FINDING THE SOURCE OF THE DRAIN If there is a drain, check and temporarily disconnect the following: Light under the hood Glove compartment light Trunk light If after disconnecting all three of these components the battery  drain can draw more than 50 milliamperes (0.05 A), disconnect one  fuse at a time and leave it disconnected until the draw is reduced Continue to disconnect the power­side wire connectors from each  component included in that particular circuit until the test light goes  off. The source of the battery drain can then be traced to an  individual component or part of one circuit Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 WHAT TO DO IF BATTERY DRAIN STILL EXISTS If all the fuses have been disconnected and the drain still exists, the  source of the drain has to be between the battery and the fuse box.  Common sources of drain under the hood include the following: The generator  Disconnect generator wires and retest. If the  excessive battery drain stops, the problem is a defective  diode(s) in the generator The starter solenoid (relay) or wiring near its  components. A common source of battery drain, due to high  current flows and heat, which can damage wire or insulation Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 HIDDEN BATTERIES Many vehicle manufacturers today place the battery under the  backseat or under the front fender. Often, the battery is not visible  even if it is located under the hood.  Whenever testing or jump­ starting a vehicle, look for a battery access point as shown here Figure 39–31 Many newer vehicles have batteries that are sometimes difficult to find Some are located under plastic panels under the hood, under the front fender, or even under the rear seat The jump-start instructions indicate that the spare tire hold-down bolt is to be used as the ground connection if jump-starting is necessary Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Why Should a Discharged Battery Be Recharged or Replaced Before Further Testing? A discharged or defective battery has lower voltage potential than a good battery that is at least 75% charged A weak battery could prevent the charging voltage from reaching the voltage regulator cutoff point This lower voltage could be interpreted as indicating a defective generator (alternator) and/or voltage regulator If the vehicle continues to operate with low system voltage, the stator winding in the generator (alternator) can be overheated, causing alternator failure Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 BATTERY SYMPTOM GUIDE See this guide on Page 416 of your textbook.  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY Maintenance­free batteries use lead­calcium grids instead of lead  antimony grids to reduce gassing When a battery is being discharged, the acid (SO 4) is leaving the  electrolyte and being deposited on the plates. When the battery is  being charged, the acid (SO4) is forced off the plates and back into  the electrolyte Batteries are rated according to CCA and reserve capacity All batteries should be securely attached to the vehicle with hold  down brackets to prevent vibration damage Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Batteries can be tested with a voltmeter to determine the state  of charge A battery load test loads the battery to one­half of its CCA  rating A good battery that is at least 75% charged should be able to  maintain higher than 9.6 volts for the entire 15­second test  period A battery drain test should be performed if the battery runs  down Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458