NFC mobile phone battery life

[philehidiot]

I've been having battery life issues with my phone for a while, despite a new battery.

Yesterday I dropped my phone atop my kit and it immediately connected to the NFC card inside. Not only that, it offered the choice of opening the appropriate RFID writing software for that particular card.

I tried it a few times and it happened nearly instantly every time. To me this means it's searching for NFC / RFID and reading them at least a couple of times a second. I assumed that, for the purposes of paying with Apple or Samsung pay, the POS terminals sent out something that triggered the NFC to communicate and that it was nearly a current drain neutral option to have on from the phone perspective (I've always gone into the software, and then gone near the card). This was with a Mifare HF RFID card.

I've turned off NFC and the battery life seems quite a bit better.

Any similar experience? Is this a bug or is it known that NFC is a power hog and searches out all the time?

[ik9000]

NFC cripples my phones. I always turn it off as I have no need or want for it. I do not and will not put my bank details into the thing most likely to get lost/stolen.

[watercooled]

and will not put my bank details into the thing most likely to get lost/stolen.

That's not quite how NFC payments work, and it's without doubt less risky in security terms than losing a bank card. Card details are not stored on the device, in fact a unique 'virtual' card is created for the device, and your original card details are never even shared with the merchant.

Depending on device, payment information is either not stored on the phone at all, or stored in a secure element not unlike that found on a chip-and-pin card, and the 'card number' stored on the device is useless apart from being used for NFC payments. Furthermore, NFC payments are only possible on a device which has lock screen authentication enabled e.g. fingerprint, PIN, etc.

They're not some unauthorised bodge to 'store' your card unbeknown to the bank. On the contrary, the setup involves the bank and are typically covered by the same sort of protections that cover card theft.

As much as it might seem like it from a high level, it's really not a case of your phone just storing card details in plaintext, and in any case it is no easier to complete a transaction with a phone than it is a payment card.

WRT the OP. Your observation about the card detection is normal with screen on, but shouldn't happen with the screen off and I wouldn't expect it to have so much of a detrimental effect on battery life. Which phone is this? Regarding the directionality of the NFC, it works both ways as you suggested.

[Spud1]

Battery life should not be massively affected with NFC< assuming you have an Android device at least (I expect Apple phones work in a similar way). As I undertsand it, there are three "modes" the NFC works under.

1) Screen on, phone unlocked - Phone polls around 10 ttimes a second for NFC - this can have a reasonable impact on battery life, but as only when your screen is on, its actually fairly low compared to everything else going on.
2) Screen on, phone unlocked - NFC is active in "card emulation" mode only - e.g. for Google Pay - uses much less battery life
3) Screen off, phone locked - NFC is not active and isn't using any battery.

Turning it off will definitely improve your battery life but I doubt more than 5% or so, less if you have a recent phone running the newer android builds.

[philehidiot]

It's a Samsung S8 running Android 9.

*Reaches out to grab the nearest Mifare card, because everyone has spare RFID cards with chip name and SN on them lying around the place*

Yeh, it only does ID it with the screen on. The battery life effect may be more for me as I often leave my phone playing youtube videos I'm listening to. That canes the battery, obviously but it has been going down faster than I expect. Turning off NFC seems to make a difference but use varies so much from day to day as does background current drain that who knows, really?

[watercooled]

Could it be a rogue app? A while ago I installed a tracking app from a shipping company which would stay running in the background and destroy battery life, causing me to miss an alarm on one occasion as it had fully drained the battery through the night. Thankfully I have a backup!

Another time I did a fairly tricky battery swap on a friend's phone (horrid glued back) which didn't fully resolve their battery drain problems. In their case a factory reset fixed it as they couldn't be bothered figuring out which app might be causing it. Unfortunately, the built-in power monitors are seldom useful so don't pay too much attention even if they suggest no particular app is at fault.

[philehidiot]

Could it be a rogue app? A while ago I installed a tracking app from a shipping company which would stay running in the background and destroy battery life, causing me to miss an alarm on one occasion as it had fully drained the battery through the night. Thankfully I have a backup!

Another time I did a fairly tricky battery swap on a friend's phone (horrid glued back) which didn't fully resolve their battery drain problems. In their case a factory reset fixed it as they couldn't be bothered figuring out which app might be causing it. Unfortunately, the built-in power monitors are seldom useful so don't pay too much attention even if they suggest no particular app is at fault.

Battery swapping on modern phones is horrific. Mine and the missus's phones needed one and so I said I'd try the process on mine and if it caused damage we'd give the phones to the local shop to sort. So, I ended up needing a new back as well as a new battery. "Fix my mess, please" was what I said to the chap. That Apple are now chipping batteries so only Apple stores can replace them is an absolute disgrace. It's not about "safety" and if it is, it's because THEY are the ones who have made it harder and harder to do. Batteries are servicable items. They need replacing. Much like brake pads on my bike - I'm capable of doing them myself and should the need arise I will replace them myself. If the manufacturer sealed them in and said "it's not safe unless you're a mechanic" I'd be asking the question - why was it possible to have a safe process before and not now?

My phone is getting towards EOL. It's no longer waterproof since the battery swap, the screen cracking has been mitigated with superglue and there's this battery issue, plus slowdown due to apps getting larger and larger (HOW CAN A CALCULATOR BE 80MB?!). It's due a replacement but I'm not paying the current asking prices. It doesn't seem worth trying to resolve the problem by setting it up from scratch when at some point this screen crack is going to hit the touchscreen layer or start crumbling on me. I don't think it has the life left in it to warrant bothering with a full reset.

It could well be a rogue app. Nothing is obviously behaving like a virus but there's a lot of... erm, networking tools, RFID read/writing tools and so on on this phone. Because normal people do this kind of thing.

[watercooled]

Battery swapping on modern phones is horrific. Mine and the missus's phones needed one and so I said I'd try the process on mine and if it caused damage we'd give the phones to the local shop to sort. So, I ended up needing a new back as well as a new battery. "Fix my mess, please" was what I said to the chap. That Apple are now chipping batteries so only Apple stores can replace them is an absolute disgrace. It's not about "safety" and if it is, it's because THEY are the ones who have made it harder and harder to do. Batteries are servicable items. They need replacing. Much like brake pads on my bike - I'm capable of doing them myself and should the need arise I will replace them myself. If the manufacturer sealed them in and said "it's not safe unless you're a mechanic" I'd be asking the question - why was it possible to have a safe process before and not now?

My phone is getting towards EOL. It's no longer waterproof since the battery swap, the screen cracking has been mitigated with superglue and there's this battery issue, plus slowdown due to apps getting larger and larger (HOW CAN A CALCULATOR BE 80MB?!). It's due a replacement but I'm not paying the current asking prices. It doesn't seem worth trying to resolve the problem by setting it up from scratch when at some point this screen crack is going to hit the touchscreen layer or start crumbling on me. I don't think it has the life left in it to warrant bothering with a full reset.

It could well be a rogue app. Nothing is obviously behaving like a virus but there's a lot of... erm, networking tools, RFID read/writing tools and so on on this phone. Because normal people do this kind of thing.

Agree with you on that. Also regarding the mechanic comment, the state of some work I've seen done by some 'mechanics' has been horrific over the years. And many won't take care of your car the way you would do yourself. You just don't know what you're getting unless you find a decent mechanic to stick with. Granted, some stuff requires specialist knowledge and training, but it's annoying how much a service stamp is worth when most of the items could be done yourself on the path in about an hour! Plus a relative had his van serviced, only to fail MOT about a week later on worn out brake pads, despite having paid extra for a brake fluid change. Figure that one out.

I have a few old phones I keep as spares. Of course, the basic phones work just as well now as they ever have. The older smartphones on the other hand? Generally fine after a factory reset, but connect to a network and allow Play Services to update itself, soon you end up with a borderline unusable, sluggish device with next to zero storage.

Like yourself I look after my devices and expect them to last. It's incredibly frustrating that software bloat often forces upgrades when the hardware is still perfectly fine. Hardware does not just get slower with age. It's a frustratingly wasteful trend.

It can be hard to diagnose what apps are causing battery drain, but a useful app I've used for testing the battery itself, is this https://play.google.com/store/apps/d...stats&hl=en_GB
Left running, and after a few charge cycles it will give you a decent estimation of remaining usable capacity. It does also allow app profiling but I can't remember how good that was as I wasn't using it for that, and I think some features require root.

[philehidiot]

Agree with you on that. Also regarding the mechanic comment, the state of some work I've seen done by some 'mechanics' has been horrific over the years. And many won't take care of your car the way you would do yourself. You just don't know what you're getting unless you find a decent mechanic to stick with. Granted, some stuff requires specialist knowledge and training, but it's annoying how much a service stamp is worth when most of the items could be done yourself on the path in about an hour! Plus a relative had his van serviced, only to fail MOT about a week later on worn out brake pads, despite having paid extra for a brake fluid change. Figure that one out.

I have a few old phones I keep as spares. Of course, the basic phones work just as well now as they ever have. The older smartphones on the other hand? Generally fine after a factory reset, but connect to a network and allow Play Services to update itself, soon you end up with a borderline unusable, sluggish device with next to zero storage.

Like yourself I look after my devices and expect them to last. It's incredibly frustrating that software bloat often forces upgrades when the hardware is still perfectly fine. Hardware does not just get slower with age. It's a frustratingly wasteful trend.

It can be hard to diagnose what apps are causing battery drain, but a useful app I've used for testing the battery itself, is this https://play.google.com/store/apps/d...stats&hl=en_GB
Left running, and after a few charge cycles it will give you a decent estimation of remaining usable capacity. It does also allow app profiling but I can't remember how good that was as I wasn't using it for that, and I think some features require root.

Cheers, will have a gander at that.

The worst I've had with a mechanic was when they routed the throttle cable so on full steering lock the throttle opened. I came off and the damage was significant. They then tried to accuse me of being unable to ride. I put in a formal complaint against the prick who was just laying into me and my bike and wouldn't accept they'd screwed up. I was livid as all I wanted was for them to fix the bike and make it rideable but they didn't give me a chance to get a word in about how I was happy to leave things be and just wanted my bike working.

The end result? BMW main dealer. I won't ever buy one again. I have screwed up before doing my own work but only in a very minor way and, because I'd done it, I could fix it. Considering that's one screw up compared to many from proper mechanics, it is definitely worth being kitted and able to do the work yourself. There are some things I will not trust myself to do (stripping and cleaning brakes as well as flushing the lines on this bike) but most I can get away with myself if I have the time, energy and inclination.

I once paid for the brakes to be stripped and cleaned and lost all braking soon after. They had done nothing other than introduce more air into the system and charged me £300 or so.

I left them a review on google stating only the facts. They also overtightened my chain to the point it barely flexed. Basically had no idea what they were doing but took the work on anyway.