1. Does the car battery leak?
Yes - Continue with A2
No - Continue with A3
2. Is the external damage visible in vicinity of leak?
Yes - Car battery not faulty. Ascertain cause cause of damage
No - Car battery faulty
3. Are the cells evenly covered with electrolyte?
Yes - Continue with A4
No - Car battery not faulty. Not manufacturing fault. Possible causes: overcharging or extreme ambient temperature.
4. Is the car battery 12.5 Volts or over?
Yes - Proceed to B to confirm cell conditions.
No - Car battery will require recharging. Then proceed to B to confirm cell conditions.
Recharging - A car battery should be capable of accepting a recharge at a minimum of 1/20th of its capacity. ie: 50 Amp Hours = 2.5 Amp charge. The car battery should be charged until all cells are gassing freely (maximum 20 hours). If the car battery will not accept a charge at the above rate or if 3 or more cells fail to respond in a prolonged charge, the battery has failed due to aging, wear and tear or deep cycling discharge. A car battery with five cells gassing freely and one/two inert cells will be covered by B1.
B - Specific Gravity Test
Functioning car batteries should have same specific gravity (S.G.) in all cells. Maximum permitted tolerance in all 6 cells is 0.030kg/dm3 between lowest and highest S.G. reading (e.g. 1.28 max and 1.225kg/dm3 min would be permitted).
Specific Gravity at 27�C in kg/dm3
1,250 - 1,280 - Indicates fully charged, proceed with test
1,200 - 1,240 - Indicates half charged, charge required
Less than 1,200 - Indicates minimal charge, charge immediately
1. The battery has One/Two adjoining cells with exceptionally low specific gravity, remaining cells 1,250 or above.
Yes - Car battery is faulty
No - Continue to B2
2. Is the electrolyte discoloured (dark brown) and /or is there evidence of excessive water consumption?
Yes - Car battery not faulty - damage caused by overcharging - test voltage regulator on car.
No - Continue with B4
3. Is the S.G. in all cells equal or above 1.240kg/dm3 in all cells after charging?
Yes - Battery not faulty - damage caused by deep cycling discharge or undercharging. Check car electrics i.e. voltage regulator, alternator or fan belt.
No - Continue with B4
4. If the S.G. in all cells is equal or above 1.250kg/dm3 after charging - proceed to test C.
C - High Rate Discharge Test
This test can only be carried out if the voltage is equal to or greater than 12.5, otherwise charge the flat car battery first. Important: read the instruction notes on the battery tester.
1. Is the result 'defective' or 'not defective'?
Defective - Car battery is faulty
Not defective - Good car battery
For car battery testers with switchable resistances (Variable Load), discharge the battery at about 3 x the 20hr rate for 10 seconds. (e.g. battery capacity 45 ampere hour (A.H.) = 3 x 45 = 135 amp(s). The voltage during discharge should be stable at 9.6 volts or over.
Testing Sealed Car Batteries
The lead-calcium-silver technology used in some car batteries means that the conventional filler plugs have been replaced by a sealed labyrinth lid, for technical reasons, and due to consumer demand.
The only fully accurate method of evaluating the condition and serviceability of �sealed� car batteries is through the use of recognised digital electronic test equipment which, together with a visual inspection will provide an extremely high level of accurate diagnosis.
In the absence of specialised test equipment, test steps A and C can be carried out.
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