AIR CLEANER GP 2249476 - Caterpillar

Battery Maintenance
The battery is the heart of the electrical system. No accurate tests can be performed on any part of the electrical system unless the battery is properly serviced and fully charged.Battery Testing
In order to determine what is wrong with a battery, you have to test it. Preform the following tests on batteries:
Specific gravity (chemical test)
Load testSpecific Gravity Test Conventional Battery
Specific gravity is the weight of a liquid that is compared to water. When you perform a specific gravity test on a battery you are determining the state of charge in the battery that is based on the percentage of acid to water in the electrolyte. The strength of the electrolyte varies directly with the state of charge of each cell. The higher the specific gravity, the greater the capability of the battery to produce an electrical potential. Specific gravity tests are done by using a hydrometer.Hydrometer
Illustration 13 g01072984
Hydrometers are calibrated in order to measure specific gravity correctly at an electrolyte temperature of 27 °C (80 °F). To determine a corrected specific gravity reading when the temperature of the electrolyte is other than 27 °C (80 °F): Add to the hydrometer reading four gravity points (0.004) for each 5.5 °C (41 °F) above 27 °C (80 °F). Subtract four gravity points (0.004) for each 5.5 °C (41 °F) below 27 °C (80 °F). This compensates for expansion and contraction of the electrolyte above or below the standard.The specific gravity of each battery cell should be tested by using the hydrometer. If water has been recently added to a battery, a hydrometer will not give an accurate reading of the battery's state of charge. Charge the battery long enough to ensure complete mixing of the water and electrolyte. Then check the battery cells with the hydrometer.Fully charged specific gravity varies in different types of batteries. Typical readings are as follows:
Table 1
State of charge     Specific Gravity    
100%     1.280    
75%     1.250    
50%     1.220    
25%     1.190    
0%     1.130    
       The electrolyte should be clear. A cloudy brown color indicates that plate material is shedding and that the battery is failing.When the specific gravity reading is below 1.250, the battery may be in satisfactory condition but the state of charge is low. Charge the battery before making further tests.When the specific gravity reading is above 1.280, the battery may be in satisfactory condition but the battery is above full charge. In use, the specific gravity should return quickly to the normal range. Make further tests in order to determine the battery's condition.The amount of variation in the specific gravities of the cells should be within 30 to 50 points (0.030 to 0.050). If cell variation exceeds this amount, an unsatisfactory condition is indicated. This may be due to unequal consumption of electrolyte in the cells that are caused by an internal defect, short circuit, improper activation, or deterioration from extended use. The battery should normally be replaced, however, a battery