[Feature] Minimum battery level threshold before background backup starts

[wenchi0920]

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

Minimum battery level threshold before background backup starts

Hi all — would love to hear what others think about this.

The idea

Let the user set a minimum battery percentage that has to be met before the mobile app is allowed to start a background backup. For example: "don't start uploading until my phone is at ≥ 80%."

Why

Immich already has a "Only while charging" option (added for iOS in #24199, and Android has had it for a while). That solves one case, but it still has gaps:

• Plugging in a phone doesn't instantly mean the battery is healthy — it may still be at 15% when the worker fires.
• On the road / away from a reliable charger, users may want backups to run only when they have real headroom (e.g. ≥ 50% or ≥ 80%), so a long upload session doesn't leave them stranded.
• Large uploads at low battery amplify overheating / thermal throttling (see Charging iPhone and uploading with immich: very hot until complete crash #22864, [Android] Overheating and battery drain: an asset the server rejects is re-uploaded in full on every backup run, 69 GB sent in 80 minutes #31637).

A simple "backup only when battery ≥ N%" guard would cover all of these without having to toggle backup on/off by hand.

Rough shape

• New setting under Backup → Background backup → Minimum battery level (slider 0–100, default 0 = off, so existing users see no change).
• Worker runs only when existing constraints and batteryLevel >= threshold hold.
• If battery drops below the threshold mid-run → pause gracefully, resume when back above.
• Composable with "Only while charging" and "Wi-Fi only".

On Android, WorkManager.setRequiresBatteryNotLow() could be a cheap first step (uses the OS's own "battery not low" signal, roughly ~15%), but the real win is letting the user pick the number.

Platform

• Server
• Web
• Mobile