During winter time, your FPV TinyWhoop is probably your current best friend. You want to boost flight time ? Time to fly with a LiHv battery: https://www.banggood.com/GAONENG-3_8V-260mAh-30C60C-Lipo-Battery-for-Blade-Nano-QX-CPX-and-Tiny-Whoop-p-1242902.html
With such battery, the max voltage reaches 4.35V (0.15V more than a classic LiPo) and the nominal value becomes 3.8V. You can probably gain up to 1min of flight time. This battery comes with a JST Ph 2.0mm connector and is compatible with most TinyWhoop machine with 0615mm motors.
Battery parameter:Gaoneng 3.8V 4.35HV 260mAh 30C/60C 1S Lipo Battery
Continuous Discharge Rate:30C/60C
Weight: About 7g
Battery Connector: Molex Picoblade PH2.0
Don’t over-charge, or over-discharge batteries.
Don’t put it beside the high temperature condition.
Don’t throw it into fire.
Don’t throw it into water.
1 x Gaoneng 3.8V 4.35HV 260mAh 30C/60C 1S Lipo Battery