Apple’s OS upgrades have been notorious for battery life, and iOS 11 has already received the usual flick from users complaining of rapid battery drain on iPhones and iPads after the upgrade. Now, a new report from security research firm Wanderer suggests that iOS 11 could lead to deadly battery drains for the iPad and iPhone; Twice faster than running iOS 10.

To reach this conclusion, Wanderer looked at a subset of 50,000 medium to heavy iPhone and iPad users running iOS 10 and iOS 11. Research shows that iOS 11 quickly removes battery life from 100 percent to 0 percent on iPhones and iPads. The current estimate is 240 minutes for iOS 10 and 96 minutes for iOS 11, the survey found.

This gives iOS 10 a rate of 0.006958 percent per second and for iOS 11 0.01739 percent per second, the study noted.

Apple released the final build of iOS 11 on September 19, and the OS upgrade was reported to have been installed more times than Android Orio within the first minutes of its release. Software upgrades bring many new functions to iPads and iPhones, including the ability to interact with augmented reality apps built using Apple’s ARKit framework.

iOS 11 could potentially cause battery depletion in newer iPhones as well, as it has animoji and face IDs that rely heavily on the camera, one of the main reasons for battery depletion. An iFixit teardown recently revealed that the iPhone 8 has a smaller 1,821mAh battery than the iPhone 7’s 1,960mAh battery. This is not very encouraging news for those who are planning to buy a new device. However, we can only judge the battery life of the new iPhone when we review them thoroughly.

Those running iOS 11 on older iPhones and iPads may try to limit the number of apps that are refreshed in the background to save battery life. Alternatively, Apple’s low battery mode can also be used to save some valuable time before turning off your device.