© 2012 Delmar, Cengage Learning Battery Service Chapter 27

© 2012 Delmar, Cengage Learning Objectives Inspect a battery and recommend and needed service Service a battery Perform a variety of tests on a battery and make a diagnosis from the results Select the best charge rate and recharge a battery Perform battery service safely Safely and correctly jump-start a car

© 2012 Delmar, Cengage Learning Introduction Batteries last an average of three to five years –Manufacturers provide a code to tell where and when a battery was made Letters A through M represent the month Number represents the year

© 2012 Delmar, Cengage Learning Battery Inspection Inspect the following: –Date code on battery label –Battery case condition –Level of electrolyte –Condition of cables and terminals –Battery holddown and tray –Built-in hydrometer

© 2012 Delmar, Cengage Learning Battery Service Replenish water through holes on the top –Use clean filtered water Lead oxidation is often found on positive post –Reduces or stops flow of current Corrosion looks like white powder –Battery acid is corrosive –Neutralized with a base such as baking soda New batteries may be shipped dry –Add new electrolyte and allow to sit 15 minutes

© 2012 Delmar, Cengage Learning Replacing a Battery Disconnect ground cable first –Do not twist battery posts –Remove hold down clamp and lift the battery out Causes of increased resistance –Battery acid vapors and air –Terminal clamp can be replaced if corroded Holddown bracket –Must hold the battery firmly in place Reinstall the battery and holddown clamps –Check that the battery starts the car

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Battery Testing: Measuring a Battery’s State of Charge Hydrometer: tests strength of electrolyte –Compares weight of liquid to weight of pure water –Batteries can freeze in cold weather Low charge battery freezes at 19°F Fully charged battery will not freeze Reading the hydrometer –Follow guidelines Built-in hydrometer batteries –Included in some maintenance free batteries

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Battery Testing (cont'd.) Refractometers: more accurate and versatile –Electrolyte is placed on measuring prism Open circuit voltage –Can determine if battery has sufficient charge Before testing, remove surface charge Remove terminal clamps Check voltage across positive and negative terminals Fully charged: 12.6 volts or higher Less than 12.4 volts: recharge

© 2012 Delmar, Cengage Learning Battery Charging Constant volt charger reduces charging current while maintaining output voltage Rate of charge: fast or slow –Keep charging voltage below 15 volts Sulfation: lead sulfate in plates becomes hard and resists recharge Slow charge: only way to completely recharge a battery –Impractical unless battery is removed from vehicle

© 2012 Delmar, Cengage Learning Storing a Vehicle When a vehicle is left for a month at a time without being started –Battery is still being discharged Half charged battery can often start an engine during warm weather –Hard on the battery –Presents extra challenges for the alternator Disconnect the battery any time it is not to be used for ten days or more

© 2012 Delmar, Cengage Learning Battery Capacity Tests Battery conductance testing –Means of quickly testing if a battery can conduct current –Indicates the amount of battery plate surface available to react chemically with electrolyte –New battery conducts 110%-140% its CCA rating –Can detect shorts and open circuits in cells –Reliable, but may give false positive result

© 2012 Delmar, Cengage Learning Battery Capacity Tests (cont’d.) Battery load testing –Battery capacity test that can be done to a battery with at least a 75% state of charge Volt-amp tester (VAT) –Used by some shops for the battery load test –Has a voltmeter, an ammeter, and a variable carbon pile rheostat –Amount of current flow through the cables is usually sensed by an inductive pickup

© 2012 Delmar, Cengage Learning

Battery Drain Test/Parasitic Load Parasitic load: circuit that causes a battery to drain –Electronic components draw small amounts of current at all times Test by using an ammeter that can read tenths of amp: less than A is acceptable Using a test light: one candlepower or smaller is acceptable Dirty battery can also cause a drain –Test with a voltmeter between the negative battery post and the top of the case

© 2012 Delmar, Cengage Learning

Battery Jump-Starting Dead batteries in good condition are common –Remove and recharge Jumper cables –Use high-quality braided-copper jumper cables –Best jumper cables are rope stranded Jump-start procedure –Connect hot cable first and ground cable last Do not connect other end of negative cable –When engine starts, disconnect the ground Remove cables in reverse order

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Hybrid Battery Service Low-voltage electrical system supplies power to control high-voltage modules –Also supplies power to engine and accessories Some hybrids use conventional battery –Mounted under the hood Others use small 12-volt auxiliary battery –Located in trunk –Absorbed glass mat (AGM) battery AGM batteries cannot be fast charged Trickle-charged at maximum of 3.5 amps

© 2012 Delmar, Cengage Learning Hybrid Battery Service (cont'd.) Most batteries are guaranteed for eight years or 100,000 miles –Replacement battery packs: $3,000 to $8,000 –Recharging requires dealership service Intake vents for battery cooling –Often on a shelf above the back seat If vents are blocked the battery will get hot Vehicle will run only on gasoline engine

© 2012 Delmar, Cengage Learning Hybrid Battery Service (cont'd.) General hybrid safety –Know what is safe to touch Orange means high voltage –System is dangerous when key is in –High-voltage battery pack contains high voltage even after depowering –Keep one hand in your pocket and do not lean against the car –Do not wear rings or watches –Wear insulated gloves