Chances are that your battery has some permanent sulfation, if it will not “take” or “hold” a charge and exhibits one or more of the following conditions:
- If your wet (flooded) Standard (Sb/Sb) or wet (flooded) Low Maintenance (Sb/Ca) battery has been not been recharged for over three months, especially if the temperature in the storage area was consistently over 77° F (25° C). [Six months for wet “Maintenance Free” (Ca/Ca) or one year for AGM (Ca/Ca) or Gel Cell (Ca/Ca)VRLA.]
- While recharging in a well-ventilated area, the ammeter does not drop to below 2% (C/50) of the expected time to recharge the battery and the battery is warm or hot. For example, if you have a fully discharged 50 Amp Hour battery and a ten amp charger, a discharged battery should be fully charged within 10 hours (2 x 50 AH / 10 amps = 10 hours).
- If the Specific Gravity is low in all cells after the battery has been on a charger for a long time.
- If the temperature compensated absorption charging voltage is correct and the battery is gassing or boiling excessively.
- Poor performance or low capacity.
- When the SoC (State-of-Charge) measured by a hydrometer, which is more accurate, does not materially agree with the SoC measured by a digital voltmeter.
Source: Greg Darden. Image by Charles Williams.