Battery Capacity (Ah) will directly influence the backup time, but it will remain compatibile with the UPS if other parameters are fulfilled. Please pay attention to the parameters: • Dimensions must be 99 x 65 x 151 +/-2 mm, equipped with T2 terminal – the battery must fit into the same place • Special UPS batteries for deep-discharge application; never use car batteries • Nominal voltage: 12VDC; Float charging voltage 13.6-13.8VDC or wider; Cycle use charging voltage 14.5-15.8VDC or wider • Maximum continuous discharge current: minimum 40A • Maximum charging current: minimum 2A • Capacity recommended minimum as the batteries being replaced • Working temperatures must fit your environment (consider for special desert/arctic applications) Hint: As it may seem that there are many parameters to check, in fact there is a common industry standard for UPSs and in most cases asking for UPS batteries at your local store will suffice.