Terrible flight times on the E013

Hi all, been really enjoying my e013 since i got it in december, bought the upgraded batteries everyone raves about and upgraded the motors, and now when i try to fly it on a fully charged battery, the max flight time ive been able to get is 15 seconds, does anyone have any ideas about what could cause it? do the batteries have super short life spans? i bought them 2 months ago maximum, thanks in advance

The pigtail that connects the lipo to the fc is a weak point and can show up as terrible flight times. Also if one motor is stiff or badly out of balance, bent shaft, bad prop, then flight times can also suffer.

I think E013 has ph2.0 soldered to the board so I assume it is not a problem (unless pins are really worn out or maybe it is broken/detached) - more likely some motors/props causes this (as you pointed).
Or maybe battery is a cause (if it is not treated properly)…