Battery diagnosis
A 30% rise in internal impedance above the reference value roughly equates to 80% battery capacity, which is the point at which the IEEE recommends immediate corrective action or replacement. Based on these recommendations, WATON has adopted the 30% value as the critical internal resistance alarm point.
WATON recommends to replace the battery for protecting your stationary battery system as the aging status of the battery is unpredictable as ΔT displayed on the graph after this 80% capacity point is reached.
We believe that the only way to ensure the integrity of your VRLA battery system by IEEE recommends is to replace the bad battery in the string when the internal resistance rises 30%.