no way to know exactly how much is balance on each CC, but you can check to know the limit of balance on each CC.
And how to check? - get one alive CC (not decline), open the any shop which have paygate available check AVS >>> choose some products and add them to carts (that their total is amount money which you need to check on this CC) >>> check out with fake address (fake zipcode, street address) >>> If the result show you that:
- AVS is not match --- that mean balance's CC is highter the total of the order
- decline - CC declined, or not enought money to pay, (the balance is lower the total of the order)
- insufficient - the balance is lower the total of the order.
Sorry for my english is not well, but I hope you understand