- Slides: 56
Battery Safety • No smoking sparks or flame near a battery. This can ignite hydrogen gas from battery. • No jewelry should be worn when working around batteries. • Disconnect grounds when servicing the battery or electrical system when able.
Safety Cont. • Never charge a frozen battery. The rapid expansion of frozen electrolyte can cause battery explosions. • Charge batteries only in well ventilated areas to allow the dispersal of hydrogen gas.
Battery after explosion
Safety Cont. • Allow hot batteries to cool down before any service. Overheating can be caused by charging too rapidly or at too high a charge rate. • Before charging make sure the charge is off. Don’t plug the charger into the outlet with the leads attached to the charger.
Safety Cont. • Never lay tools on or near battery. Use a fender cover on top of the battery while working near the battery to prevent tools from contact posts. • Do not get battery acid on clothing. • Wash hands immediately after handling batteries.
Electrolyte • Mixture of sulfuric acid and distilled water • Poured into each cell until plates are covered • Warning: electrolyte causes serious burns or blindness if it comes in contact with your skin or eyes!
• Operate the starter, ignition, and fuel injection during cranking • Supply electrical power when the engine is not running • Supply electrical power when current demands exceed alternator output • Act as a capacitor (stabilize voltage) • Store energy for extended periods
Battery Ratings • Cold cranking amps (CCA) – Amps available at 0 F • Cranking amps – Amps available at 32 F • Reserve capacity – Time in minutes before battery is discharged • BCI group – Size and post configuration
Example BCI Group LWH Polarity 24 10. 3, 6. 8, 8. 9 24 F 75 95 R 10. 3, 6. 8, 8. 9 9. 1, 7. 3 15. 6, 6. 9, 7. 5 L/H pos R/H pos Terminals Top SAE Side SAE Top SAE
Cold Cranking Amps Rating • Current the battery can deliver for 30 seconds at 0 ºF (-18 ºC) while maintaining terminal voltage of 7. 2 volts (1. 2 volts per cell) • Expressed as cold cranking amps (CCA) • Indicates ability to crank the engine at cold temperatures • Typical applications: – 305 CCA for small 4 -cylinder engine – 450 CCA for 8 -cylinder engine
Cranking Amps • • Abbreviated CA Cranking amps available at 32 ºF CA typically about 20% higher than CCA Don’t go by CA rating in cold climates
Ratings Decal 2
Battery Voltage • Open circuit cell voltage is 2. 1 volts • Cells are connected in series • A 12 -volt battery has 6 cells and an open circuit voltage 12. 6 volts
• As battery temperature drops, output is reduced – chemical process is slowed – battery cannot produce as much current
Side Post – Less Obvious
Capacity Testing • Applies ½ CCA for 15 seconds • Battery must be at least 75% charged • Can be used to destroy good batteries
Conductance Testing • Midtronics tester • Passes a small amount of a/c through battery • Quick and easy • Not 100% • Can also test starter and generator (sorta)
Sulfation Test • Charge at 30 -40 amps for three minutes • Check voltage with charger running • Should be less than 15. 5 V • More than 15. 5 V indicates plates not taking a charge
Factory AGM Batteries • Cannot be charged at a high rate • Used in HEV and EV • Not used to crank the engine
Replacement AGM • Requires special charging rates • Cannot be used to replace cranking batteries in many applications
Parasitic Draw • Key-off battery drain • Some is normal, about. 050 -. 075 A (50 – 70 m. A) • May be higher • Too much = discharged battery
Key-Off Memory • • Clock Radio presets Memory seats, mirrors, climate, steering…. Engine control module – idle, fuel control…. Transmission control module – shift tables… Anti-theft system RKE SAS and more…
Parasitic Draw Testing Precautions • Leave battery connected if possible • Vehicle may require an hour or more to shut modules off • Any disturbance (proximity of smart key) can cause vehicle to wake up • Read service info for specific vehicle
Parasitic Testing • Keep meter or test light connected • Remove one fuse at a time and note draw • If draw decreases, problem is likely in circuit protected by that fuse • Following wiring diagram for the fuse to isolate components
Parasitic Draw by Voltage Drop • Measure the voltage drop at each fuse • Refer to the voltage drop – draw table
Battery Cycling • Repeated charging and discharging • Deep cycling – going from a very low charge to full charge – can shorten service life
Battery Inspection and Tests • • OCV – should be 12. 6 or above Insure correct CCA Check corrosion/leakage/voltage loss Check hold down condition Conductance test Capacity Parasitic draw
Battery Leakage Test
Battery Cleaning Wash with baking soda and water, and do not let debris enter filler openings
GM-Style Hold Down
Import Hold Down
Battery Terminal Test