Battery is usually selected based on the backup time required by the customer and the previous choice of Inverter. Common battery capacities are 100 AH and 150 AH. Most of the customers who need 135 AH battery go for 150 AH battery. This is due to the fact that 150 AH gives considerable backup time compared to 135 AH. Same reason people go for 100 AH battery instead of 90 AH. However this depends on customer to customer.
For a little additional investment, customers get more advantages and benefits. Hence we recommend our customers to consider price benefit difference.