I have been observing battery drain for some time and narrowed down to cell standby battery drain as Airplane mode doesn't drain battery. My phone is connected to cell tower that's it. No Internet, no background services, no wifi, stand by mode but still overnight battery drain is 10% in 8 hours. I just have dual physical sim and that was the reason buying Samsung instead of Apple. It looks like Samsung hardware is still not capable to handle cell reception which apple and old basic phones handled very well. Samsung still not improved after so many years and its a battery sucking machine.
Anyone else observed this issue and how to fix it ?
Using two sims in the phone is a known battery resource usage drain @mmtech
If one or both of your signals are poor then the phone can drain battery trying to remain connected.
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