Iris 3500 battery

I’m new to flying quadcopters and have run into a problem I could use some help with. I bought 4 batteries with the Iris in February of this year. They all seemed to work fine up until about a week ago, now they will only power the Iris for about 60 seconds and I get the low battery warning at about 10.5 volts. When I look at Mission Planner I can see the voltage dropping but, the percent of charge still stays up in the 80 to 90 percent range and then after disarming, the voltage goes right back up over 11 volts. I haven’t done any special care of the batteries, sometimes I store them charged, sometimes not charged, for weeks. I have been flying it with the gimbal gopro and long legs for 6 -7 minutes. They all seem to charge normally with the charger included with the Iris. I’m trying to determine if the batteries have gone bad on me or there is something wrong with the Iris. I’d appreciate any insight on this.
Thank you

Could be a case of a damaged cell, it could charge but it won’t retain much of the charge so all the stress would be on the other two cells

Thanx for your reply Francisco, I just received zippy compact 4000 3 cell batteries in the mail today, I’ll give them a try after I solder some xt60 connectors on them.

The batteries definitely went bad on me. Everything is working fine with the new zippy compact 4000’s, 13 minutes without Gopro and gimbal. Bought the Hitec battery charger and using the storage feature after flying.