You can estimate recharging time by dividing the batteries ampere hours (Ah) by the chargers Ah output. Keep in mind that multistage chargers taper the current after approximately 80% to 85% of the charging is completed so it will take about one additional hour to fully complete the charge.
For example, a 35Ah battery being charged with a 4 amp capacity charger would fully charge in: 35 Amp hours / 4 Amps  + 1 hour = 9.75 hours