Open-Circuit Voltage Test

For accurate voltage readings, batteries must remain idle (no charging, no discharging) for at least 8 hrs, preferably 24 hrs.

   1. Disconnect all loads from the batteries.
   2. Measure the voltage using a DC voltmeter.
   3. Check the state of charge with the Table below
   4. Charge the battery if it registers 0% to 75 % charged

 

    State of Charge

    Discover 

    Discover 

    SOC %

     Flooded

     EV Dry Cell

     100%

     12.80-12.60

     12.90-12.80

     75%

     12.40

     12.60

     50%

     12.20

     12.30

     25%

     12.00

     12.00

     0%

     11.80

     11.80

After charge, if any battery measures a voltage variance of greater than 0.3V from any other battery in the sett, then balance charge or equalize the set.

Remeasure each batteries voltage and if the battery continues to register a variance or below the Temperature Compensated values illustrated in “How can you tell if a battery is fully charged” or “How can I measure my batteries State of Charge”, the following conditions may exist:

 

  1. The battery is old and approaching the end of its life.
  2. The battery was left in a state of discharge too long.
  3. A weak or bad cell is developing.

Batteries in these conditions should be taken to a specialist for further evaluation or retired from service.

 

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