Why is my phone battery draining overnight even with all apps closed?

[Dennis40]

My new phone’s battery drains almost 20% overnight even with all my apps closed and battery saver on. I’ve checked for obvious things like a weak signal, but I’m wondering if there’s some hidden setting or background process I’m missing that could cause this kind of idle drain.

[EricLW]

I had this after a software update. Even with apps closed the device kept radios partially awake and wore down overnight. The culprit turned out to be a background service that reenabled itself and woke the phone a few times.

[LukeIM]

I chased it for days and finally found a background sync was doing a few light checks every hour. It looked quiet, but those wakeups add up when signal is weak.

[ScottH]

Could a degraded battery be the real problem? Mine did that where the meter looked fine but the capacity was lousy and idle drain looked worse after a year.

[MasonW]

I keep blaming it on small things like the always on display catching a few extra minutes of attention at night, or a notification channel that won't rest. Sometimes it feels like a phantom drain.