WiFi calling drains battery like crazy

[Moriarty]

For the last few months, my iPhone 6S battery life had been terrible. Couldn't figure out why – I tried deleting apps, restoring the whole phone, everything... it would drain something like 3% per hour, just sitting on standby (the "usage" figure in the battery stats was always like 1/4 of the standby time, so way more than I actually use the phone). I went from using maybe 30% of my battery in a day's use, to 75%.

I finally figured out that WiFi calling, which had been switched on automatically in iOS 11.3, was causing the drain. I didn't even know that WiFi calling existed! After I switched it off, everything seems back to normal...

Hopefully this might help someone else. It sure is a pain when the thing that's draining your battery doesn't even show up in the battery stats.

 

[ScooterComputer]

I finally figured out that WiFi calling, which had been switched on automatically in iOS 11.3, was causing the drain. I didn't even know that WiFi calling existed! After I switched it off, everything seems back to normal...

Hopefully this might help someone else. It sure is a pain when the thing that's draining your battery doesn't even show up in the battery stats.

I have been thinking along these same lines recently. Spending the summer in two places where my SE stays on Wi-Fi Calling nearly 100% of the time because of poor cell reception, I started incidentally noticing that my battery life wasn't as good as I thought I had remembered. But thinking on it, and realizing that I was getting phone calls in places where I had zero cell reception even when the iPhone was asleep, it occurred to me that the Wi-Fi radio must not be going into sleep mode as it normally would when the phone was locked and not on power. And it sounds like what you are seeing reflects that too. FTR, I'm still on iOS 10.2.

Certainly seems that Wi-Fi Calling, especially if it is set as "on" by default, should be something that shows up in Battery stats. Users should be informed of trade-off costs. (Though, in my case, I'd not trade phone service vs no phone service.)

 

[Moriarty]

I have been thinking along these same lines recently. Spending the summer in two places where my SE stays on Wi-Fi Calling nearly 100% of the time because of poor cell reception, I started incidentally noticing that my battery life wasn't as good as I thought I had remembered. But thinking on it, and realizing that I was getting phone calls in places where I had zero cell reception even when the iPhone was asleep, it occurred to me that the Wi-Fi radio must not be going into sleep mode as it normally would when the phone was locked and not on power. And it sounds like what you are seeing reflects that too. FTR, I'm still on iOS 10.2.

Certainly seems that Wi-Fi Calling, especially if it is set as "on" by default, should be something that shows up in Battery stats. Users should be informed of trade-off costs. (Though, in my case, I'd not trade phone service vs no phone service.)

This is probably a bug, and I'm reporting it to Apple as such. If not, why would such a battery-draining feature be enabled on 11.3 by default?

My understanding is that Wi-Fi calling sets up a persistent connection between your phone and the carrier's servers. If push notifications draw very little battery power, I don't see why Wi-Fi calling has to take so much. I do wonder if my carrier is doing something wrong, e.g. sending way too much data to keep the connection alive.

 

[rcyoaxn]

This is probably a bug, and I'm reporting it to Apple as such. If not, why would such a battery-draining feature be enabled on 11.3 by default?

My understanding is that Wi-Fi calling sets up a persistent connection between your phone and the carrier's servers. If push notifications draw very little battery power, I don't see why Wi-Fi calling has to take so much. I do wonder if my carrier is doing something wrong, e.g. sending way too much data to keep the connection alive.

The issue here isn't that Wi-Fi calling drains your battery faster -- in fact, it's likely that you are saving battery life by using it. The actual problem is the poor reception. Your phone expends much more battery trying to maintain a poor cellular signal. When a phone doesn't have a good connection to a cellular tower it uses more power, pings towers more often, and sends more powerful signals to cellular towers. If you want to test this, put your phone into airplane mode and then re-enable Wi-Fi. You'll still be able to use Wi-Fi calling (depending on carrier) and you should experience much better battery life.

If, though, you have improved battery life by turning off Wi-Fi calling -- yeah, that does sound like a bug.

 

[Moriarty]

The issue here isn't that Wi-Fi calling drains your battery faster -- in fact, it's likely that you are saving battery life by using it. The actual problem is the poor reception. Your phone expends much more battery trying to maintain a poor cellular signal. When a phone doesn't have a good connection to a cellular tower it uses more power, pings towers more often, and sends more powerful signals to cellular towers. If you want to test this, put your phone into airplane mode and then re-enable Wi-Fi. You'll still be able to use Wi-Fi calling (depending on carrier) and you should experience much better battery life.

If, though, you have improved battery life by turning off Wi-Fi calling -- yeah, that does sound like a bug.

Make no mistake, I have improved my battery life by turning off Wi-Fi calling. I get 1 or 2 bars at home, and by turning Wi-Fi calling off my overnight battery drain decreases from about 25% (way too high) to about 5% (normal). My weak cell signal is not the culprit here.