Solution for insane Signal battery drain.

Nakatt

In order to prevent Signal to drain your battery like crazy, you need to be able to remove it from "Unrestricted battery usage" to "optimized battery usage".

The only way to do so is to not have Signal set-up as a SMS app. A shame but that's how it is.

MetropleX

Nakatt if you don't have Play Services installed for FCM (Firebase Cloud Messaging) to be the push method for Signal then Signal requires a websocket connection to be maintained to push Signal messages to your device.

Removing it's battery optimisation exception will result in delayed message delivery as this interferes with the websocket connection.

It is that connection resulting in the higher battery drain not the SMS use. While Signal and any other app that uses websockets for push need a battery exception their battery usage is still relative.

The best way to judge battery life is longevity against Screen On Time.

mythodical

For what it's worth, I've always left Signal on the default battery profile (Optimized). It starts at boot as expected, and reliably delivers messages in real-time via WebSockets throughout the day. I believe it's the Alarms and reminders special permission that allows this to work as intended. The same goes for K-9 Mail with push enabled.

The only apps of mine that have required unrestricted battery optimization are DAVx⁵ and Syncthing.

Still, I agree that it is WebSockets that is likely draining the battery a bit quicker than Play would, regardless of SMS functionality.