Thor Forums

[Beau388]

The internal resistance for AGM batteries is about 10% of that of flooded batteries. This allows for much faster charge rate, because with a lower resistance there is less internal heat in the battery case. Still the recommended charge rate is 10% to 13% of the 20 hour AH rating for AGMs as well as flooded batteries. Thus with a 550AH @ 12 volts battery bank, the max charge rate would be 55 to 71.5 amps for the bulk charge. Charging a LA battery too fast can cause some undesirable chemical reactions; as well as, warping the plates because of excessive localized heat. This is why a flooded battery must be fully charged before equalizing. As slow discharge followed by an immediate slow recharge rate will result in extended battery life when compared to fast discharge and recharge rates.