Charging your cell phone

ultrarunner2015

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Nov 23, 2014
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Hi;
Recently, I did some research online to find whether it is a good idea or a bad one to keep my cell phone plugged into its charger when I'm home. From what I have read, the thing to avoid is full cycles - going from near empty to full - but keeping the phone at or close to 100% isn't good either, according to several sources. They go on to say that the optimal charge for a Li-Ion battery is around 80-85%, and that short charging cycles during the day to keep the battery at that level is optimal. They also say that if you are going to leave the phone on charge all night, or for any extended period, you should remove any case from the phone, to allow heat to dissipate more efficiently.

I have been running an app that plays soothing sounds while I sleep (roughly 8 hours per night). When I run this app, I normally leave the phone plugged into its charger. Without thinking, I would normallyset the phone's volume up fairly high - which I am sure drains the battery pretty fast. I don't need to do that - now that I am thinking more clearly - because the phone's output is connected to the Line-In on my stereo receiver, so I can set the phone's volume as low as I can, then crank up the stereo receiver to get the desired volume level on the speakers.
I am sure that following the above procedure will extend the battery life of the phone, and may eliminate the necessity to keep the phone on charge overnight.

Just as with everything else online, there are conflicting views on the subject of Li-Ion battery maintenance, but it does appear that most agree on the 80-85% "sweet spot" for the battery in a cell phone.
I am thinking now that perhaps there is a way to design a charger that will not charge the battery fully, but charge it instead to 80-85%. If there was some sort of signal sent out over the USB/charging port on the phone, it would be a great help in designing such a charger, but I doubt very much that there is such a signal. Instead, could there be an app that would sense the battery level and stop charging at 80-85%?

Any ideas on this?

Thanks;
FW
 

TinderBox (UK)

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Since my android phone and tablet have built in battery`s i dont really want to go though the expense of replacing the battery, so i only charge to 80% and dont discharge below 20% if i can help it, I have had my tablet for over a year and have only fully charged it 2-3 times just to recalibrate the battery gauge.

I use an app called GSam Battery Monitor, you can set alarms to go off when certain battery levels are reached, but you still have to unplug the charger yourself to prevent the charge continuing.

John.
 

reppans

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Mar 25, 2007
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I've looked in this and rely on THIS Battery University article and THIS Military study on different Li-ion cycling habits - they pretty much reconcile with each other.

Basically after high heat, it seems the biggest wear factor for Li-ions is high voltage - peak AND average. Deep cycling appears to rank third, after heat and high voltage. So, according to the military study, if you typically use 50% capacity per day, then charging:
- nightly 100-50-100 (75 avg/half cycle) is the most stressful for the battery/results in the greatest permanent capacity loss.
- every other night 100-0-100 (50 avg/full cycle) is next most stressful
- nightly 75-25-75 (50 avg/half cycle) is next
- nightly 50-0-50 (25 avg/half cycle) is easiest on the cell.

Although the lowest peak and avg voltage appears easiest in the battery, you have zero power reserves, and so is impractical.

I personally charge my iPhone/iPad using light timers on a ~80-40-80 cycle (I average ~40%/day), plugging them in nightly (only). Charger is set to run ~6am-8am or just before I wake and start using them. This minimizes my peak and average voltages, yet give leaves me enough reserve battery power (~40%) for emergencies (and I can also powerbank my flashlight/NiMh gadgets if need be).

Once set, it only costs me a couple of seconds to adjust charge time (if needed), but most folks, even here, already consider that way too OCD/anal. YMMV ;).
 

ultrarunner2015

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Nov 23, 2014
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57
reppans said "I personally charge my iPhone/iPad using light timers on a ~80-40-80 cycle"
I thought of using a timer as well, but the only ones I currently own are of the mechanical type, and therefore not very accurate in setting, and also, the "click" it makes could be loud enough to wake me (probably not if I am playing the relaxation music). I can try one of those timers, just to see how it works - and if it awakens me, I can purchase a solid-state model.
I also have a Li-Ion battery pack I use to recharge the phone while on backpacking treks (away from electrical outlets), so I might be able to work that into the equation as well.

Further study has told that any app that measures charge/capacity, is not going to have the ability to stop the charge, as that is something controlled by the phone, and not user accessible.
For now, the timer seems to be the best option - especially since I already own one.

All that said; how many people keep a phone long enough to have an issue with the battery? It seems that 2yrs is about the expected life of a phone, and I don't think the battery is going to suffer enough loss of capacity within that time to be an issue.
 

ShineOnYouCrazyDiamond

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Aug 18, 2009
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CT, USA
Have any of you guys used Qi wireless charging?

I used it on my iPhone for a while via a Qi case. I also used it on a work Samsung S5 via a wireless charging back. I found that they are terrible for battery longevity. The only iPhone battery I ever had to replace was that phone that I wirelessly charged. Also - the Samsung S5 battery started to swell after about 6-8 months.

I think the additional heat created by the induction charging combined with improper regulation of the charging cutoff probably caused the problems.

The Samsung S6 has it built in to the phone and it seems to be more reliable, but I only use it in a pinch.

My current habit with my personal iPhone 6 is that I use Waze on my way to and from work (about 45-60 minutes drive). During that time I plug the phone in to power the GPS app / charge it. I have found that I'll be at around 80% or so in the morning, charge on my way to work, use during the day and be around 45-50% at the end of the day and charge on the way home.

I guess I am in the worst range as far as the military test goes, but I've found it's a heck of a lot better than keeping the phone plugged in all the time at 100% and not letting the battery cycle at all.
 

MidnightDistortions

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Illinois, United States
In my experience it might be ideal to simply charge the battery. I think the 80-100% might be valid more if you are not planning to use it. I had issues where the battery would die unexpectedly and so I just find it more effective to recharge the phone 2-3 hours before I need to leave without being able to recharge it. I dont use the phone a whole lot so most of the time at the end of the day or so I still have 70-80% left and when I'm at home I primarily use my home PC. Every so often, like once a month I let it drain to about 20-30%. I haven't encountered a dead battery much doing that but every once in a while I do get that issue. To me though its better to have the battery at 90%+ then it being at 30% or lower on the regular basis.
 

uofaengr

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Jun 24, 2015
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644
Coming from an iPhone a year and a half ago to an LG G3 with bigger and replaceable battery (got another battery and charging cradle for free) it's gonna be hard for me to go back to a phone without a replaceable battery. It's nice to run mine dead, swap out the battery and let the other one charge in the meantime. Not how I always do it obviously, but I've got options other than being tied to a charger. I don't overthink it..batteries are cheap enough.
 

ultrarunner2015

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Joined
Nov 23, 2014
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57
Here's an idea:
Purchase an inexpensive DTMF decoder board. $20 from China (incl. s/h).
Install GSAM or other app on phone that provides alarm for higher/lower charge %.
Create ring-tone using DTMF tones.

This decoder board will accept audio from the phone's headphone jack. It has relays to control load. Connect charger through one of the relays on the board.
create ring-tones that use DTMF tones to turn the relay on the external board on or off at charge % set in GSAM app. (you may have to purchase GSAM to get the functionality for alarms).
These boards have 4 relays. Each relay is energized when a tone (1-4) is received. Only one relay will be energized at a time, so if you connect your charger to relay #1, then sending a "1" to the decoder board will turn the charger on. Sending a 2, 3, or 4 will turn it off.
You will need to buy or build a stereo splitter plug/jack to enable you to connect your headphones and the DTMF board to the phone.
Set up the GSAM app to send ring-tones which play the DTMF digit you need.


I'm going to check to make sure I can generate the DTMF tones and set them as ring tones before I purchase a board.

I use my phone at night to play "relaxation music" through my stereo system. I keep the amplifier's volume turned up, so that I can keep the phone's volume low to preserve battery.
My only concern about using DTMF tones is that, depending on how loud the tones need to be in order to be detected by the circuit, I might be awakened when they are played. I will need to purchase the module and play with it to determine that, unless the seller (Ebay) can provide me with that info.

The specs given by the seller state that the module runs on 12VDC, and the relays can handle up to 250VAC @ 5A.


Note: The relay board can be wired into the input or output of the phone charger. Output would be preferable, as it is only 5V and the input is line voltage. Only issue with output is that you will need to break a wire in the cable between the charger and the phone, unless you purchase a jack and plug that will fit the charger's plug and plug into the phone, so you can create your own breakout for the relay without messing up the charger's cable.
If you are going to wire the decoder board into the 115VAC line to your charger, then you must install it into an approved electrical box. A single-gang plastic box would suffice. I would also recommend fusing the 115VAC input to the module.

What do you think? Too much trouble? or is this worthwhile?
 
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