Can I pause Arc overnight to save battery?

I’m a new user of Arc (in the last few weeks) and am finding this app incredibly helpful (and motivating) for tracking walking. However, I find it uses a lot of batter, including overnight when I’m sleeping. Is there any way to ‘pause’ Arc when I get home, until a certain time (i.e. 6am or 8am) the next morning? At the moment my workaround is to manually ‘stop’ the app by swiping it up; then, I have to remember to restart it in the morning (though the notification helps with that).

Thank you.

Matt might be able to give more insights, but my understanding is that Arc in “sleep mode”, i.e. when it knows you’re at home and are unlikely to leave, will only consume minimal battery. Do you really see a considerable difference in battery usage, or is it more of a hunch?

Hi @fra!

Arc will automatically go into “sleep mode” when you are stationary. And once it’s learnt your habits at a particular place (eg home) it will know when to sleep more deeply, consuming the lowest amount of energy until you’re predicted leaving time in the morning.

This is likely only achieving a placebo effect. If you swipe the app closed it will be automatically restarted some time after (perhaps in 15 minutes, or perhaps several hours later). In general, swiping apps closed will actually negatively impact your phone’s battery life, causing the battery to drain faster rather than slower.

If you absolutely do not want Arc recording overnight, even in Arc’s low energy “sleep mode”, then you can turn off recording from Arc’s Settings tab.

However the best workaround to get the most battery life by morning is to ensure your phone is plugged in overnight. In general this will also result in your phone running more efficiently and smoothly during the day, due to it allowing the phone to run all its scheduled housekeeping tasks overnight.

Apple apps, system services, and third party apps all schedule various background housekeeping/processing tasks that will only run when the phone is plugged in to power and idle (ie you’re not using the phone at that moment). The ideal and most efficient time for these tasks to run is overnight, while the phone is plugged in to power. If they don’t get a chance to run overnight they might get delayed until later in the day, impacting system performance until they eventually complete, or potentially not getting run at all until some chance in another day.

If you do tend to plug your phone in and leave it idle during the day, for example at your desk while at work, then the scheduled tasks might still be getting completed each day. But it really is ideal to get them all done overnight, so that the phone wakes up with you in the morning all tidy and ready to go, with a full charge and all of its housekeeping already complete.

Thank you, both, for your replies!

Thank you—I wasn’t aware of this option! (On the iPhone SE 2, it’s just below the screen, so you have to swipe down to find it.) It currently takes 5 taps to turn off recording (open Arc; go to settings; swipe down to find it; tap ‘turn off recording’; tap to confirm). Is there a way I can automate this to turn off at a certain time (i.e. from Shortcuts)? It would be even better if it could be set to turn back on at a specific time too, or if there were a way to get Shortcuts to turn it on when (for example) an alarm goes off in the morning. Any chance this is possible? Still, I’m glad the option is there; it makes things much easier (though I have to set a Reminder to turn it back on each morning …)

I’ve tried an experiment the last three nights. I charged the iPhone to 100% then went to bed. On the first night, with Arc running as normal, the battery was down to 68% in the morning; on the next two nights, with Arc swiped closed (2nd night) and then with recording turned off manually (3rd night), it was down to only 95% each time. It has been worse in the past (down to 25% or so, if I left Arc running overnight …) so maybe Arc is still learning (I’ve been using it for a few weeks now).

Thanks for this. I’ve avoided charging overnight after a number of media reports of devices catching fire while charging. Is this a concern?

There’s a couple of feature requests on the Changemap site for Shortcuts support, and it’s definitely a possibility! I recommend voting for these ones to increase the chances of me being able to focus on building the feature soon.

It sounds like iOS isn’t automatically restarting Arc overnight if it’s been swiped closed. This could make sense, given you’re not moving anywhere overnight, so the “significant location change” reason for restarting the app isn’t triggered. The other main reason iOS would restart the app automatically is if iOS decides it’s time to run one of Arc’s scheduled background tasks. But with the phone unplugged iOS won’t decide to run any scheduled tasks, so that trigger won’t happen either.

Definitely not a concern! iPhones are designed to be left plugged in overnight - it’s their intended way to be used. The only potential risks are things like uncertified / low quality third party chargers, or uncertified / low quality third party replacement batteries. And really the incidences of either of those causing danger with iPhones is very low too. Apple have some details here.

iPhones these days also intelligently learn your charging and usage habits and automatically time their charging so that the phone will likely spend most of the night not charging, waiting instead to finish charging just before you wake in the morning. This optimised charging allows you to leave the phone plugged in overnight without any concern about it prematurely ageing the battery. There’s details about that here.

Oh, I meant to reply to this bit too:

Yes, this is a reasonable guess. Arc gets better over time at predicting when it should sleep more deeply or more lightly. It also learns how much to “trust” location data while stationary, based on your feedback.

It’s typical for the location data inside some buildings to be very unreliable, drifting around for tens or even hundreds of metres. And when this happens iOS can also often misreport the achieved accuracy level, for example reporting that the location data is accurate to within 10 metres when really it’s 100 metres away from the real location.

When iOS misreports the accuracy like this it messes up Arc’s algorithms that clean up messy data - Arc is being told the location data is good when really it’s quite bad, and Arc has no way of knowing it’s being lied to. So that leads to Arc waking up and starting to actively record again, even though you haven’t gone anywhere - it’s been mislead into wasting energy.

So Arc’s workaround for that is to calculate a “trust factor” for location data at each place you frequently visit. It learns this based on your corrections to drifting data, from the Individual Segments view. So for example if you look at a visit to your home and see that on the map there’s a mess of lines wiggling randomly about, and the Individual Segments view shows a similar mess of nonsense moving activity types, you can go through some of those and correct them to “stationary”, and Arc will then learn that at that location the phone’s reported location data accuracy is probably a lie, and then know to put less trust in it in future.

That “trust factor” then allows Arc to stay in sleep mode for longer, doing less wasteful wakeups overnight, and using less battery.

So if you ever do see a mess of nonsense lines on the map when looking at the details view of your home visits, it’s worth going into Individual Segments and cleaning some of those up, correcting them to “stationary”. It’s not necessary to clean up all of them - Arc will still learn its “trust factor” as long as you correct at least some of them. Then in future visits you’ll see that far fewer of those nonsense moving segments will appear, because Arc will have learnt to ignore them and stay asleep instead.