Sealed Maintenance-free Battery Is Also Called Maintenance-free

  •   A sealed Maintenance-Free Battery is also called a maintenance-free battery, and its working principle is the same as a traditional wet battery or unsealed battery. Like unsealed batteries, sealed car batteries still contain electrolytes. However, you cannot add liquid to the sealed battery to replenish the electrolyte level. Because it is sealed, you cannot use a hydrometer to test this type of battery. Instead, a digital voltmeter is needed, and the price of the voltmeter is only $20.

      step 1

      Remove any type of terminal cover on the Sealed Gel Battery. You must be able to access the negative terminal and the positive terminal at the same time. Also, check your voltmeter to make sure it is set to DC power scale and 12 volts.

      Step 2

      Connect the leads of the digital voltmeter to the sealed battery. The positive lead must be firmly connected to the positive terminal, and the negative lead must be firmly fixed to the negative terminal.

      Step 3

      Observe the voltage reading displayed on the digital voltmeter. If the Sealed Maintenance-Free Battery is fully charged, the reading should be approximately 12.8 or 12.9 volts. Very low readings, such as 10.0 to 11.0, may indicate that the battery is short-circuited. In this case, it may be necessary to replace the battery with a new one. Reading in the range of 11.0 to 12.0 indicates that the battery is low and needs to be recharged.

      Step 4

      If necessary, charge the Sealed Maintenance-Free Battery. Use a 12-volt battery charger set to low amperage to slowly charge the battery. Depending on the severity of the battery discharge, the time to fully charge may vary from a few hours to a whole day. Check the battery charger frequently to ensure that the battery is charged properly.

      Step 5

      After the battery is fully charged, turn on the car headlights for about five minutes. Then turn off the light and wait about 10 minutes. This will remove the surface charge, which may interfere with the accuracy of the test. If the sealed battery has been removed from the vehicle, let the battery stand for two to eight hours to remove the surface charge.

      Retest the sealed battery by connecting the digital voltmeter in the same way as before. If the reading is low again, the Sealed Maintenance-Free Battery cannot be charged and needs to be replaced.