A bootable-USB write is one of the hardest jobs you can give a phone: processor, storage and USB port all running flat out for half an hour. Batteries dive and backs get hot. None of that has to kill your write — if you prepare for it in the two minutes before you press Start.
PCs shrug off a 6 GB write. Phones do not — the job runs through a battery, a passively cooled slab of glass, and a USB controller that is also feeding power to the pen drive. The pattern is always the same: the phone that starts at 30 percent dies at 80 percent written, and the phone that overheats slows itself down until the write crawls. This page is the short discipline that prevents both endings.
The simple rule: do not begin a full ISO write under half battery. The drive takes its power from the phone, so the phone is feeding two devices at once. If your phone and adapter support charging while OTG is active — some do through a powered OTG hub or a Y-style adapter — use it; the phone then holds its charge while it works. Honesty: many phones cannot charge and host USB at the same time, and there is no setting that changes hardware. On those, the answer is a full battery at the start and the fastest drive you have, so the job ends before the battery does.
Android's battery saving is the silent write-killer. Aggressive power management can freeze or close the writer app the moment the screen turns off — and a frozen write is a corrupt drive. Before starting, open the phone's battery settings for the app and set it to unrestricted, keep the app visible on screen during the write, and let the screen stay on (plugged in, it costs nothing). This is one job where you babysit the phone instead of pocketing it.
Sustained writing warms any phone; a hot phone protects itself by slowing the processor, and the write slows with it — sometimes to a crawl that looks like a hang. Help it breathe: take the case off, lay the phone face-down on a cool hard surface, keep it out of sun and off soft bedding, and do not charge it with a fast charger at the same time if it is already hot, since fast charging adds its own heat. Warm is normal. Too hot to hold comfortably, or a temperature warning on screen, means stop, let it cool fully, and start the write again — a restarted write is annoying, a cooked battery is expensive.
No drama and no damage: a dead battery mid-write leaves a half-written, unbootable drive — nothing worse. The pen drive itself is not harmed; it simply holds an incomplete image. Charge the phone properly, then write the drive again from the beginning — never assume the partial write can be "topped up". The same rule covers any interruption: cable knocked out, app closed, phone restarted. Whatever broke the write, the fix is always a fresh full write on a charged phone, which is exactly why the prepared-technician advice in this set — a ready-made USB in the drawer — exists.
The video's write runs in real time — note how the phone is set up while it works, and copy that arrangement before your own write.
▶️ Watch Full VideoLight use is fine, but every extra job competes for the processor the write needs and risks disturbing the app. The safest pattern is the boring one: phone on the table, writer app on screen, hands off until it finishes.
Usually heat. The phone reduces its speed to protect itself, and the USB write slows with everything else. Cooling the phone — case off, hard cool surface, no direct sun — restores most of the speed; a cooler room helps more than any setting.
An occasional emergency write is ordinary heavy use and nothing to worry about. Doing it weekly at high temperature with fast charging would age a battery faster — one more reason the everyday answer is a ready-made USB, with the phone method kept for real emergencies.