Battery Capacity Test
NOTE:
To perform this test use a high rate discharge tester, Rotunda Starting/Charging Tester VAT-40 (078-00005), or equivalent, in conjunction with Rotunda 73 Digital Multimeter (105-R0051), or equivalent.
- Turn the control knob on the VAT-40 to the OFF position.
- Turn the multimeter selector switch to the DV volt position.
- Connect VAT-40 and multimeter positive test leads to the positive battery post and both negative test leads to the negative battery post. The multimeter clips must contact the battery posts and not the VAT-40 tester clips. Unless this is done, the actual battery terminal voltage will not be indicated.
- Turn the load control knob in a clockwise direction until the ammeter reads approximately half of the cold cranking amps of the battery.
- With the ammeter reading the required load for 15 seconds, note the multimeter reading. Avoid leaving the high discharge load on the battery for periods longer than 15 seconds.
- If the multimeter reading is 9.6 volts at 70° F (21°C) or more, the battery has a good output capacity and will readily accept a charge, if required.
- If the voltage reading obtained during the capacity test is below 9.6 volts at 70° F (21°C), and the battery is fully charged, the battery is defective and must be replaced. If unsure about the battery's state of charge, charge the battery.
- After the battery has been charged, repeat the capacity test. If the capacity test battery voltage is still less than 9.6 volts at 70° F (21°C), replace the battery. If the voltage is 9.6 or more at 70° F (21°C), the battery is satisfactory for service.
- If the battery is found to be discharged only, check for a loose drive belt, loose electrical connection, charging system performance, and perform drain test. See BATTERY DRAIN TEST .