Why does my S3 battery sometimes drain very rapidly and other times drains normally?

[James882]

S3 Battery Sometimes Drains Very Rapidly Other Times Drains Normally

After charging overnight, the battery meter on my S3 always reads 100%. Some days, everything works dandy and the phone works great for the day. Other days, the battery rapidly declines to 50% or even to almost 0%.

Here's a screenshot of my phone's battery on a bad day:


No idea why this is happening. The battery is about 1.25 years old and is the one that came with the phone as new. I've tried resetting the system cache as suggested in other places.

 

[Rukbat]

Re: S3 Battery Sometimes Drains Very Rapidly Other Times Drains Normally

A weak mobile signal (tan, not green) uses a lot of battery. Note where you are on which days, and you'll prohbably see a pattern - a lot of usage when you're in this loction, not much usage when you're in that location.

Also, having the screen on for long periods eats a lot - the screen is one of the largest battery consumers (but not as large as having almost no signal).

 

[James882]

Re: S3 Battery Sometimes Drains Very Rapidly Other Times Drains Normally

Agree with all you said in general Rukbat. But I don't think this is the cause for me specifically - notice the timespan of the graph where the batter drops from about 50% to about 5%. This occurs over the course of only about 6 or so minutes, and with the screen off at that. The phone is also on a solid wi-fi connection, so it's not even using a mobile data network. The cell signal is weak, but not extremely weak, and I don't think bad enough to justify this much battery usage.