Your charger seems won't auto-cut. So you have to time it by yourself. If you can measure the charging current, a 1300mAh will take approximately an hour to charge fully at 1.3A, 30 min at 2.6A etc ...
I suggest you buy a B6 charger from KWS, it only costs $2XX but you need to buy a 12V power supply. B6 can charge almost all kinds of battery and it is worth an investment.