Possible to automatically disable fast charging at night?

[Coldblackice]

For the sake of battery health, since I don't need fast charging at night while sleeping, I'm wondering if it'd be possible to automatically disable fast-charging between certain hours, and then re-enabling it in the morning. Would this be possible (and without root)? TIA

[Wibbly]

Not found a way to control charging at all, except by using a wifi controlled plug on the charger to turn off the charger at a designated % full via Automagic.

On my bed stand I use a normal/low current charger anyway, as there's no hurry.

[vertigo]

AFAIK, charging can't be manipulated in any way without root, since it requires access to CPU functions (the CPU is what regulates the charging). Wibbly's idea is quite creative, and probably your best bet if you want to actually charge it overnight. Keep in mind that, more than likely, it's the topping off more than the fast charging that harms the battery. IOW, you're (probably) better off with respect to battery health to charge it quickly to, say, 85% (that's where I usually unplug) in the evening then unplug it before bed than to slow charge it all night but let it get to 100%. So just disabling fast charging isn't going to be doing a whole lot for you. Of course, if you have the time and want to really baby the battery, the best bet is to slow charge (with a non-fast charger or using an adapter that's not fast-charge compatible) AND unplug before bed. Either way, unless you have really poor signal or you have apps misbehaving and draining your battery--in which case you should deal with that--the phone shouldn't lose much at all overnight, which is easily replaced by a short charge period in the morning.

I generally charge in the evenings and, occasionally, plug in for a bit in the morning, which is plenty to get through a typical day. I try not to go over 85% very often and, while I'm not as good at it as I am about overcharging, I try not to go too low too often, either, which is also not good for the battery. My phone is an original Moto Z Play, and I'm constantly seeing people with this phone complaining about their batteries being shot, yet mine is still going very strong. Granted, it could just be a fluke, and my one data point doesn't mean much, but I like to think it has to do with how I charge it. I also predominantly used slow charge on it for a long time, since I typically wasn't in a hurry, but the past several months I've been almost exclusively using fast charge, just because I changed my setup, and the battery does seem to have degraded a bit over that time. Whether that's because of more fast-charging or just showing its age, or if it even has really been degrading faster, who knows. Supposedly, though, fast-charging has little effect on longevity.

[Micky Micky]

Hello,

Not really answering the question but as I understand it the biggest problem for battery life is heat. Fast charging can be an issue here.

You can monitor battery temperature with Automagic.

Hope this helps

Micky

@Wibbly - thank you, a Wifi plug is on my shopping list!

[vertigo]

Yes, heat is bad, but over/undercharging is also very bad. You'll get a lot more life out of a battery doing more frequent charges from e.g. 25-50% than from 25-100% or worse 5-100%. Batteries are rated for how many cycles they can undergo, e.g. 1,000 cycles would be 0-100% 1,000 times, or 25-75% 2,000 times, but the latter will result in significantly less wear, since they don't like being topped off. As for heat, I personally monitor it with GSam, and while it does get fairly warm when charging, it doesn't seem to be a problem (fast-charging works by adjusting the voltage to keep the current, and therefore the heat, down, and doesn't let it heat up too much), though that's why slow charging may be better, since it wouldn't get as warm. But from what I've read, how low you let it get and, probably more importantly, how high you charge it likely has a much more significant impact than how fast you charge it. Heat would certainly be the most significant factor if it were allowed to get hot enough to damage it, but it's kept low enough that the effect is (likely) minimized to the point it's not a real issue, and certainly not as much as the charge levels.

That said, if you're really worried, as I said before the safest bet is to avoid fast charging whenever possible. Or you can get a OnePlus, which performs the voltage regulation in the charger instead of the phone, so the waste heat is generated there instead, so the battery stays much cooler, in turn allowing for faster charging. Of course, the downside is that fast charging requires their proprietary chargers. Also keep in mind that wireless charging, though slower, may actually create more heat and therefore be more harmful (though, again, it will be kept in check so as to not get too warm), since it's less efficient, meaning more heat is generated. Also, my phone gets warmer just driving around on a sunny day, even when it's relatively cool (mid-70s) with the phone in the dash mount than it does when fast-charging (~44-45C vs 39-41C), though slow charging is certainly much cooler (34C -- note this is a one-time measurement I just did for the sake of this post, and the fast-charging was done from ~50-65% whereas the slow-charging was done from ~65-78%, and the battery gets warmer when charging at lower levels with fast-charging, so it may not be completely accurate, but is close enough for this).

I think I'm actually going to get a WiFi plug as well. I really like the idea of automating it so I don't have to worry about it and can leave it plugged in overnight in the event I find the need.

[Wibbly]

Where does the evidence come from that normal discharge in a phone to empty, damages the battery?

[vertigo]

I don't remember where exactly I've seen it, and most likely it was in multiple places, but here's a good overall source and a good summary: https://batteryuniversity.com/learn/art ... _batteries

From that page:

the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses.

and

A partial discharge reduces stress and prolongs battery life, so does a partial charge. Elevated temperature and high currents also affect cycle life.

Note: 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.

Table 2 shows very clearly the effect: 100% DoD results in a cycle life of 600, whereas an 80% DoD results in 900 cycles, so 50% more life by discharging 20% less (900 * 0.8 = 720 "full" cycles vs the 600 from a 100% DoD).

[Wibbly]

I read that differently. DOD is the difference between the start and end battery levels, not the absolute charge level. The articles encourage lower absolute charge levels and low DOD too. So start at 3% and end at 1% is just a 2% DOD which would be just fine even though the state of charge is very low. Limiting DOD is about saying 2x a 2% DOD and charging in between is better than 1x 4% DOD regardless of the charge level. So charge more often if you have the choice, all other things being the same.

What's bad is high temps and high states of charge.

So the ideal strategy to maintain battery longevity is to try and keep it at a low state of charge, charging it whenever it drops a little to keep the DOD between charges low. That has to be traded with the way we actually want to use our phones. So when, say, your day at home doesn't require a long time before the battery would go flat, maybe maintain at 25% and recharge as soon as it gets to 15% (repeated 10% DOD and quite low charge state), and keep the phone out of the sun and not over a room heater.

Personally, I try to maintain the battery between 75% and 35% as a practical compromise day to day, and will charge to 100% only when I think I will really need full capacity. It's too easy to get obsessive about it. Nothing lasts for ever, and we have our phones to be convenient...

[vertigo]

As I said, I've read it elsewhere as well. Here's another quote from that page:

The largest capacity loss occurs when discharging a fully charged Li-ion to 25 percent SoC (black); the loss would be higher if fully discharged.

Of course, it's unclear whether they mean more (linear) loss just because of the increased cycle count from discharging further, or if they mean non-linear loss due to increased stress from letting it go down lower.

You might be right. I may be misremembering, or may have misunderstood, or the source(s) I got that from may have been wrong; regardless, I would still say it's best to try not to let it get too low. If it happens every now and then, that's one thing, but I wouldn't make a regular habit of it. In fact, I used to do it quite a bit, and have made an effort to do so less often over the past couple years or so. Still, my phone often goes below 10% and fairly often even down to 5% or less. I'm much more concerned and careful about overcharging it, though that happens too, sometimes. But I try to do like you do, only with a wider range of around 10-20% and 85%. And some days when I'm at home, I'll plug it in at 40-60% and let it charge to 70-85%. Other days when I'm going to be away for a while, I'll charge to 100%. As you said, it's important to balance this all with usability and to not get obsessive about it. It's easy to mange within reason and with minimal effort, and shouldn't be stressed over. Just charge when you can and unplug before it gets higher than 80-85% if you can without it causing you to worry about whether you'll be able to make it to your next charge, which means don't leave it plugged in overnight. But if you do occasionally, it's not going to kill your battery. Simple rules.

I've seen people argue against that, saying that if you're only cycling between say 20 and 80 percent, you're only getting 60% capacity from your battery even when new, which defeats the whole purpose, since you'll likely have more than that even after a few years of full charge-discharge cycles. There's certainly truth to that, and to each their own, but I look at it more as, if I don't need to use more than 60% to get me through the day, why not take care of the battery so it lasts longer, so now that I've owned the phone for a few years, I can still get slightly >95% of a full charge cycle out of it when I do need it. To each their own. If someone's the type of person that gets a new phone like clockwork every year, then yeah, this is all a waste of their time.

Here's a couple other informative quotes from that site:

The worst situation is keeping a fully charged battery at elevated temperatures.

That is, don't charge a battery to full then store it in a warm environment, e.g. don't keep a fully charged phone/tablet/computer in the car (obviously, that's not ideal even with a non-fully charged one, but fully charged is worse).

Heat increases battery performance but shortens life by a factor of two for every 10°C increase above 25–30°C (18°F above 77–86°F). Always keep the battery cool.

So based on that, the difference between slow- and fast-charging of ~5C in my example means fast-charging theoretically is shortening the life of my battery by ~50-60% over slow-charging, but just having my phone on the dash while driving is shortening it by another ~50% vs fast-charging. I guess the lesson there is to absolutely not charge it while in the dash mount unless I absolutely have to. However, that's a quote from their discharge article, and it's referring to temperature during discharge. I would assume it affects it similarly during charging, but charging is for a brief period, so a 5C difference for say 40 minutes of charging is going to be a lot less of an effect on life than a 5C difference during a several hour discharge.

That last quote also reminds me of a Car Talk episode that shocked me, because they had no idea why turning the headlights on for a couple minutes before starting a car would help it turn over on a cold morning.

[Wibbly]

Agreed.

I also have a WiFi switch to limit max charge when using my phone as a satnav in the car to avoid worst of all worlds. Sun on the phone and high charge levels. Also an AM based screensaver to minimise screen burn from satnav being on all the time at high brightness