I never had luck using AAA rechargeable batteries with the MiniMed 530G. For some reason, the 530G found the batteries not to have enough charge even after I had recharged them completely. Since I started on the MiniMed 670G, I have been using Sanyo Eneloop AA Rechargeable batteries with no issue. The batteries might not last as long as the non-rechargeable ones but they last long enough before they are fully discharged.
Rechargeable Batteries Work with the MiniMed 670G