CAPACITY OF A BATTERY

CAPACITY OF A BATTERYThe quantity of electricity which a battery can deliver during single discharge until its terminal voltage falls to 1.8 V per cell is called the capacity of a battery.

The capacity of battery or cell is expressed in ampere-hours and denoted by AH.CHARGE INDICATION A fully charged battery has a specific gravity of 1.28. However when it falls to 1.15, the battery is fully discharged. To get good life of battery keep the specific gravity more than 1.18.Specific gravity Condition1.280 to 1.290 100 % charged1.230 to 1.250 75 % charged1.190 to 1.200 50 % charged1.150 to 1.160 25 % chargedBelow 1.130 Fully dischargedBattery RatingsBatteries are rated 4 ways:CCA (Cold Cranking Amps)CA (Cranking Amps)RC (Reserve Capacity)AH (Ampere Hour)CCACold Cranking AmpsIndicates the ability of a battery to deliver a specified current at a low temperature. It is determined by the amount of current a fully charged battery can supply for 30 seconds at 0F without the voltage falling below 7.2 Volts CACranking AmpsThis is the same test as the CCA rating, except it is at a higher temperature (32F instead of 0F)RCReserve CapacityIt determines the time in minutes a vehicle can be driven after the charging system fails The length of time a fully charged battery (at 80F) can supply 25 Amps before the voltage falls below 10.5 VoltsAHAmpere HourThe amount of current a fully charged battery (at 80F) can supply for 20 hours without having the voltage fall below 10.5 VoltsHydrometerwith floatwith balls

HYDROMETER To check the specific gravity of sulphuric acid , an instrument called hydrometer is used. Which works on Archmedeies principle. However the state of battery can be checked by checking :Voltage : When the terminal voltage is 2.1 to 2.5 V per cell, the battery is fully charged. But when it become 1.8 V per cell, the battery is fully discharged.Colors of plates : When battery is fully charged , the anode is of chocolate color and cathode is of grey color. When battery is fully discharged the color of both plates is whitish.Voltage Tests Open Circuit

Turn on the headlights for 2 minutesTurn off the headlights and connect a voltmeter to the battery, red lead to positive, black to negativeIf the battery is good, it will read above 12.2 voltsIf below that, charge the batteryLoad Test ConnectionsMake sure the battery is fully chargedConnect the red lead or the VAT-40 to the positive terminalConnect the black lead to the negative terminalClamp the green clamp over the black leadVAT-40 Connections

Load TestingTurn the Load Increase control until the ammeter reads 3 times the amp-hour (AH) rating or one-half the cold-cranking ampere (CCA) rating Hold that reading for 15 secondsRead voltmeterA good battery will read at or above 9.6 voltsBattery should be at 70FCase Drain TestsUses a voltmeter with the black lead hooked to the negativeUse the red lead to touch the case in the middle of the batteryIt should read less than 0.5 voltsA larger reading indicates you should clean the top of the battery with hot water and detergentParasitic Drain TestRemove the negative cableHook a test light between the negative post and the cableIf the light glows, there is a problem in the electrical systemLook for lights on inside the truck or trailer or the regulator is badCable Corrosion TestUsing a voltmeter, hook the black lead to the negative post, and the red lead to the cable connector while turning on the headlightsReading should be 0 volts

Do the same with the positive post and cable