Overnight Charging & Phone Battery Life: BMS Control, Overcharging & Potential Harm Explained

Hello, recently I read a few articles about leaving the phone connected to the charger overnight shortens its life because the battery is "overcharged" after reaching 100% charge. And here the question arises, by what right should the battery be overcharged if it does not directly charge the battery, but through the bms controlling the battery applied in the phone, which probably disconnects the battery from charging after charging it. What then is the harm of this phenomenon?

You're right. There is a battery charge/discharge system that prevents overcharging.

No harm to the phone, because charging is disconnected after charging the battery. There is only "harm for the pocket", because the charger connected to the mains draws electricity all the time.

If it's not loading, it's downloading next to nothing.

Yes, and the phone does not magically drain the battery when connected to it

There is something about it. In the latest IOS for the iPhone there is an option to optimize charging. That is, the phone collects information about the user's daily routine (and what does not collect now?) and after connecting the charger for the night, it charges up to 80%, and just before the usual hour of unplugging the charger, it charges up to 100%.

Since I bought a model with wireless charging, I try to charge only to about 80% and with a low current because I have a 5W pad. Effect? Over a year of time and 100% battery. At the same time, a business phone that does not have such a solution and is charged with a cable up to 100. Differences as in the attached pictures.

No hysteresis applied?

Sometimes it happens that the phone needs more energy than the charger can provide to charge and power the phone. Then you can observe the battery discharging when the charger is connected.

sylweksylwina wrote:

Sometimes it happens that the phone needs more energy than the charger can provide to charge and power the phone. Then you can observe the battery discharging when the charger is connected.

Is it possible at all? Assuming that the charger has these 1-1.5 A, what would have to happen on a functional phone to have a higher power consumption than the charger provides

Do you think it's a problem to load the processor so that it downloads more than 5-7W? For example, run a high-definition game on it. In addition, a bright screen, radio transmission (on-line game) and the battery runs out.

The phones can run the same games as on the PC, where 500W power supplies are installed. Xbox One, depending on the demand for computing power, draws 75-130W (measured). And there the same Fortnite, WoT as on the phone.

Once I connected an old iPhone SE with a cable to a radio that supports CarPlay. I had navigation on it, music from the phone, but the battery with 20 for two hours of driving climbed to 35%.

Weak charger, corroded contacts and, as a result, a voltage drop causes the phone to switch to USB charging mode, which is slightly below 0.5 A at 5 V. And then some models can discharge the battery faster than it charges (e.g. when working as a car navigation ).
As for battery life - lithium batteries feel good in a certain range of charge levels, opinions are divided, but their life is shortened by both long-term discharge (below 20%) and full charge (above 80%). It shortens, means accelerates aging. And the connected charger will not allow you to go down to, for example: 70%. In practice, the phenomenon is visible in devices working under the charger 24 hours a day non-stop, where the battery dies after several months (there is also a lack of charging cycles and temperature, and not only the time when the battery has over 90% charge). With typical use (battery full for 12 hours every 48 hours, but device cold during that time) I don't know if it will make a difference.
Charging with low current is a separate issue - the better the charging profile (an algorithm that calculates when to give a dozen or so W and more and when only low power) the battery will last longer and charging (in a certain capacity range) will be faster, the issue of temperature control, construction of the cell itself, cycles work, etc. A lot of factors.

szymonm01 wrote:

Assuming that the charger has these 1-1.5 A, what would have to happen on a functional phone to have a higher power consumption than the charger provides

At 1A, it's probably not a problem - screen processor, etc. For example, on my phone, html5 tests in the browser + screen brightness at max and the consumption is calmly approaching 1A according to Ampere. Well, but at my place the charger from the set is 5V 4A

The topic is about leaving the phone charging overnight. I assume that during this time (rest) the phone is charging - it gets more W than it uses.

Even if it connects to USB mode, a lower charging current will not hurt the battery.

Li-ion batteries do not like to be fully charged. Not only on phones. The screwdriver I used in the manual said to charge it fully only when we will use it immediately.

In my old laptop (13 l) the manual recommended to remove the battery when we want to use the mains power for a long time. Leaving the battery in a laptop shortens its life.

Now it is not recommended, and in the latest constructions impossible (eg business DELL E7470)
Current computing power requires batteries as a buffer.

But in turn, I am positively surprised by the power consumption - it can go down to 6W during operation.

My "home" Dell E4310 won't go below 15W (disk replaced with SSD).

ak44 wrote:

Leaving the battery in a laptop shortens its life.

My friend followed this advice and for 1.5 years she did not use the battery in her Toshiba. After connecting it to the computer, the battery showed 0% and did not charge
Meanwhile, in another Toshiba for 9 years I keep the same battery that I got with the laptop. Computer used almost every day, at the university, and then on the way to work for 2 hours a day. When I have the opportunity to plug into an outlet, I plug in and work on the cable. When I don't have it - I work on the battery. When it was new, it lasted 5h, now only 1.5h, but in my opinion it's still a sensational result for such an exploited equipment.

Regarding overnight charging - Sony also has this function, it only charges up to 90%, and reaches 100% at the expected end of charging.

sylweksylwina wrote:

At 1A, it's probably not a problem - screen processor, etc. For example, on my phone, html5 tests in the browser + screen brightness at max and the consumption is calmly approaching 1A according to Ampere. Well, but at my place the charger from the set is 5V 4A

In my Galaxy Note 8, the power consumption has never exceeded 1.9A, the dedicated charger is 2.1A, at max load it really does not charge the phone

Just in Samsung and other brands Fast charging is about increasing the voltage. And the battery and the components of the phone know what the voltage is - and a greater voltage difference often means greater losses (greater losses - more heat, more heat - slower processor and slower charging), although with today's converters these are not large values. OnePlus just went towards a higher current supplied from the charger, and it works great.

While charging my E6553 phone, I see that the charge status LED changes to green after reaching 90%, it takes several dozen minutes to reach 100%.
And now the crux of the matter; if after this hour and reaching exactly 100%, I turn on the game (click Bubble Breaker) the battery level drops to 99% after a minute, but when I leave the phone connected to the charger for a few hours and turn on this game, then the 100% state lasts longer the record is 7 minutes.
The conclusions are:
- the battery after reaching 100% is still being charged
- the status indicator does not show the actual state of energy in the battery, but the theoretical state of this battery assumed by the programmer

My phone - depending on the time of calls - I charge every few days, it is often attached to the charger for several hours after the green LED appears.
In my subjective opinion, the working time between charges has not changed since I got it in May 2017 (it was bought in January 2015).

In my opinion, the service program does not provide for higher percentage indications, because an indication above 100% would lead to ambiguity on the principle that you can not pour more than the specified capacity into the bottle, and anything above it would be treated as cheating, while presenting the voltage in volts (V ) is not an option, because for most it is a meaningless numerical value. Only the program inside converts the battery voltage, charging current, charging curve - into a percentage indicator.

The parameters of the battery are not repeatable, like the meter pattern, and they have scatters, like a cross-eyed hunter , many series are simply poorly made, which means that they do not maintain the assumed parameters. I will add that in times of "mass", even the most expensive brand, with the highest price - does not provide the highest quality.
It's almost a lottery - one will hit, many won't.

In another section, TOSHIBA TV was written about, which have one thing in common with it - the inscription, because the interior is identical to the TV from mass market stores.