Battery Testing
Before performing any battery testing or charging operations. the external condition of the battery should be checked for damage, such as a cracked case or leaking terminals. The top surface of the battery and terminals should be clean and free from dirt, acid accumulation, and corrosion. A dirty battery cover can form a type of conductor which will permit current movement between posts. possibly discharging the battery if the vehicle is not driven regularly.Hydrometer
The measurement of the acid concentration in the electrolyte is referred to as specific gravity of the electrolyte. The measurement of the specific gravity of the electrolyte is an accurate method for determining the state of charge of the battery.
On standard batteries, a hydrometer is inserted into each cell to draw off some of the electrolyte. The specific gravity is then read and compared to the chart to determine the state of charge of each cell.
State of Charge Specific Gravity Open-circuit Voltage
100% 1.260 2.10
75% 1.230 2.07
50% 1.200 2.04
25% 1.170 2.01
Discharged 1.110 1.95
If all hydrometer readings are low but equal, the battery can be considered chargeable. Once a battery has been charged and the cell readings remain below 1.250 or if there is more than 0.050 difference between the cells, the battery should be replaced.
Load Testing
Once it has been determined that the battery is in good condition and properly charged, proceed with the load test as follows.
1. Connect voltmeter and battery load tester across battery terminals according to the manufacture's instructions.
2. Remove any surface charge from the battery if the battery has just been charged with a battery charger or the vehicle's charging system. To remove a surface charge, apply a 300 amp load across terminals for 15 seconds. Discontinue load and wait for 15 seconds to allow the battery to stabilize before proceeding with the test.
NOTE:
Do not remove surface charge from batteries that have been in storage.
3. Battery temperature should be estimated by touch and also by the surrounding temperature it was exposed to during the few hours before testing. Select the nearest estimated temperature in the table above and determine the minimum voltage which must be maintained while the battery supplies a specified electrical load.
4. Refer to the chart above for the correct load value of the battery being tested. If the vehicle is not equipped with a Land Rover or authorized Land Rover battery, see the battery manufacturer's specifications for load test values. If load test specifications are unavailable, a good rule of thumb is to apply 48-50% of the battery's cold cranking amperage as a load test value. For example, if the battery in question is rated at 575 cold cranking amps at 0°F (usually printed on battery cover), then the battery should be load tested at 280-287 amps.
5. Apply a specified load selected from the preceding table for 15 seconds, then observe voltage while the load is connected. Turn off load immediately after noting voltage.
6. If the voltage is below the value as specified by the table in step 3, replace the battery. If the voltage equals or exceeds this value, the battery may be returned to service.