LTC4041: Supercapacitor need a long time charge

Hi I'm Dann,

I bought the LTC4041 eval board form mouser to Raspberry Pi power backup. I have tried in first time, it was work properly and could charge the series supercapacitor 10F in 1-2 minutes. But when I'm not using it in one month, and I have tried again, it has a weird issue, the charging time need 10-15 minutes from 0.6V until 4.5V. The other, the board have a ringing in inductor or supercapacitor. I'm analyzed maybe there was something wrong with supercaps performance (ESR) but I'm not sure. Could you help me guys, what's going on with that?