For these ones: https://www.amazon.com/ThorFire-Rechargeable-Collapsible-Flashlight-Emergency/dp/B00NIL1DFO/ https://www.amazon.com/ThorFire-Rechargeable-Collap

For these ones: https://www.amazon.com/ThorFire-Rechargeable-Collapsible-Flashlight-Emergency/dp/B00NIL1DFO/ https://www.amazon.com/ThorFire-Rechargeable-Collapsible-Fla... I can crank for a few seconds and it will last a few minutes. They become gradually dim after that, and I never measured how long it took for them to go completely dark.