KOReader battery drain: causes and fixes
KOReader should not noticeably shorten an e-reader's battery life. If it does, it is almost always Wi-Fi, the refresh setting, a plugin, or the frontlight — not the app itself.
Last updated September 2026
An e-reader running KOReader should still last weeks, not days. If yours is draining fast, work through these — roughly in order of how often they are the cause.
Wi-Fi left on
This is the big one. KOReader does not turn Wi-Fi off when it finishes syncing, and an idle Wi-Fi radio is the largest drain on an e-reader by far.
- In Network settings, turn on “turn off Wi-Fi after N minutes” of inactivity, or disable Wi-Fi on suspend.
- If you do not use progress sync, OPDS or online dictionaries while reading, just leave Wi-Fi off and turn it on deliberately.
Full refresh on every page
A full-screen flash costs more power than a partial update. Menu, then the gear, then Screen, then the full-refresh interval. Every 1 page is the cleanest image but the most power; every 6 pages is a common compromise. On a device that does not ghost much, a higher number saves a real amount over a long book.
The frontlight
Obvious, but easy to miss: KOReader’s brightness and warmth are separate from the stock reader’s, and it is easy to leave it brighter than you need. Lower it, and check the auto-warmth / auto-brightness settings are not fighting you.
Statistics and other background work
- The Statistics plugin writes to a database on every page turn. The cost is small, but if you have a huge history it adds up; you can trim or disable it in its settings.
- Auto-sync in progress sync wakes Wi-Fi on every book open and close. Fine if Wi-Fi is managed as above; a drain if Wi-Fi then stays on.
- The News downloader or Wallabag plugins only run when you trigger them, but a scheduled fetch (if you set one up) will wake the radio.
Suspend behaviour
KOReader relies on the device suspending properly when you put it down. If it is not sleeping — screen stays warm, battery falls overnight — check:
- “Sleep after N minutes” is set and short.
- No plugin is holding the device awake (disable them one at a time for a day to find it).
- On BOOX and other Android devices, that Android’s own battery settings are not keeping KOReader running in the background; restrict it there.
A genuinely faulty battery
On an older device that will not hold charge no matter what, the cell is worn. KOReader cannot cause that, and on many e-readers the battery is replaceable.
The short version
Turn Wi-Fi off after a few minutes idle, set full refresh to every few pages rather than every page, drop the frontlight, and make sure the device is actually sleeping when you set it down.