Test eq bulk cycle

I have a D8 flooded lead acid battery 1400CCA and 255Ah capacity. it is 6 years old on a boat with a 3 stage 12 amp charger which is on all the time when the boat is not in use.
battery is now very low in specific Gravity 1175 less than 40% capacity. it’s voltage 3 days after a full charge is .  this is far too high and we suspected sulfation to possibly be the cause of the higher voltage.(we read this somewhere)
we then overcharged it at 16 volts and it only drew 3 amps . After about 17 hours the SG had gone up to above 1200 about a 50% charge. a remarkable improvement.
my question to you all is why is the battery voltage still high on open circuit and why is there only 3 amps of charge at 16volts. should we continue to overcharge it ?
Hugh

The contraction of the Hadley cells at the SGM explains the southward displacement (weakening) of the monsoons associated with the Hadley circulation (figure 54 f), and the decrease in wind strength at the Santa Barbara basin that increases precipitation (figure 54 e). The expansion of the polar cells explains the increase in wind strength over Iceland (figure 52 d), that appears to depend on Milankovitch forcing. With the expansion of the polar cells there is an increase in polar circulation driven by the strengthening of the Siberian high, that produces an increase in salt deposition over Greenland (figure 52 a & b).

Test eq bulk cycle

test eq bulk cycle

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