Summary
Highlights
Building on a previous study about fast charging, this video tackles new questions: Does using your phone while charging hurt the battery? What about heat, cold, or wireless charging? To answer these, a long-term experiment was conducted with 24 phones, divided into groups for various tests, starting with normal charging and 'charging while using' scenarios.
After 193 days and thousands of hours of testing, the results showed that 'charging while using' did not significantly hurt battery health more than normal charging. The primary factor affecting battery life was found to be the number of charge cycles, not simultaneous usage, despite 'charging while using' leading to slightly higher temperatures.
Further tests investigated the effect of extreme temperatures. Phones in a hot box (around 35°C/95°F) showed a slightly higher battery degradation (9.6%) compared to normal. Cold box tests were inconclusive due to an anomalous phone failure. The overall conclusion is that normal temperature ranges are safe for battery life.
Many users feel that the last 1% of battery life and the drop from 100% to 99% last longer. Testing revealed that the 100% to 99% drop held for 3-5 times longer than other percentages. This is because phones may display 100% before being truly full to avoid the perception of an immediate drop upon unplugging. The 1% lifespan was found to be random.
The study also addressed wireless charging and frequent charging. Wireless charging was found to be no worse than wired charging for battery health. Interestingly, avoiding deep discharges by frequently charging (e.g., from 80% to 95% wirelessly) actually resulted in better battery retention, suggesting that charging whenever convenient can be beneficial.
iPhone's battery health indicator was found to be roughly accurate, showing general trends despite not being a precise, real-time measurement. The video concludes by emphasizing the effort put into the tests to provide users with peace of mind. It also highlights the importance of recycling old phone batteries due to their potential environmental harm.