AUKEY EP-T31 Battery Life problem

Hi…

After receiving the EP-T31, I fully charged both the case and the earphones after removing the transport foil. Pairing was problem-free, but I received the first acoustic battery warning messages even with 50% remaining charge (according to the display in the Bluetooth settings of the smartphone)! At 40%, but no later than 30%, the earphones regularly switch themselves off and have to go back into the case to recharge!

I have already experienced this several times, so far it has not been possible for me to use the earphones for longer than 80-90 minutes at a time, starting from 100% battery charge, at a volume setting of 60-max.75 %! When there is still sufficient charge available according to the battery indicator in the Bluetooth settings, the end is reached! This cannot be correct!!!?

I have owned various other Bluetooth InEars before, but they behaved completely differently. I got the acoustic battery warning at 20% or 10%, but even then they were still usable for a long time!

What could be the reason for this or what can I do?