Less Than Full Charge For Cell Phones

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
Hello,

Recently i had to change the battery in my cell phone because it was bulging and this got me thinking.
I learned a long time ago that charging an Li-ion cell such as an 18650 to only 4.15v instead of 4.20 volts leads to longer life, and charging up to only 4.10v leads to even longer life.
Now 4.10v amounts to roughly 87.5 percent capacity which is almost 90 percent. The life expectancy could go up by a lot though, at least 2 times longer possibly even more. That's not bad considering we only lose 10 percent capacity.
Also, most people keep an eye on their percentage anyway so if it gets too low they charge it again.
Even losing 20 percent would not be too bad (about 4.05v max) if we dont need the full run time of the phone before the next charge can be done. A charge to 80 percent could lead to four times the life expectancy.

It's kind of funny i never applied this idea to my phone. I guess I was always worried that if i really needed it i didnt want the battery to run down before i was done using it. In a power outage (we had one the other day due to a fire in town) you really want your phone to have a good run time. So the trade off is longer battery life vs emergency or unexpectedly long run time.

But thinking this through, i then have to wonder what would be a good minimum percentage before the next charge. Previously i was charging constantly and if i was out or something and it went down to even 85 percent i would quickly charge it back up again to 100 percent. So i was doing the worst possible. Electrical stress is often measured in terms of voltage and/or current so the more voltage the more stress. 100 percent is worse than 90 percent and 80 percent is less stress than either.

So if charging to only say 80 percent, what would be a good minimum. I hate to go too low like 20 percent.
What do you think? How are you charging your phone and what minimum do you allow before charging again?
 

oz93666

Joined Sep 7, 2010
724
What do you think? How are you charging your phone and what minimum do you allow before charging again?
... the benefits stop at 3.93V (65%) .. you then get 3000 cycles , compared with 400 if charged to 4.2(100%) .... this is for Li-ion ... I'm not sure if Li-po is the same..

I don't think there are any benefits by recharging before the phone says 0% (is that what you meant by 20%) the circuitry should prevent harmful excessive discharge ...

All you need realistically do is pull out the plug before 100% is reached .
 

KeithWalker

Joined Jul 10, 2017
596
My solution for a longer battery life is to use the phone as a telephone. I do my internet stuff on a computer where I have a much larger screen and a real Keyboard. I use a good quality camera for my photography. I really don't have to be in touch with social media 24 hours a day. I use my Acer phone in power management mode with all the online applications turned off and blocked. Google is by far the biggest culprit in using your phone's battery. It constantly monitors any activity and stores data and preferences on the cloud and it regularly updates it's self even if you have wifi turned off.
I use my phone as a phone with voice and text, with no access to data. I can still get on the internet with it in a wifi area if I really need to. The service costs a total of $25.00 per month. It lasts an average of eleven days between charges. That will increase the life of the battery by more than five times.
Regards,
Keith
 
Last edited:

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
... the benefits stop at 3.93V (65%) .. you then get 3000 cycles , compared with 400 if charged to 4.2(100%) .... this is for Li-ion ... I'm not sure if Li-po is the same..

I don't think there are any benefits by recharging before the phone says 0% (is that what you meant by 20%) the circuitry should prevent harmful excessive discharge ...

All you need realistically do is pull out the plug before 100% is reached .
Thanks for the reply.

What i meant by 20 percent was if we discharge to 20 percent and we then have a main power failure (so we can not charge normally) we are stuck with 20 percent for the entire time the power line power is down. So here in the US that means 120vac line goes down, so we can not recharge. That means if any calls come in we have to talk quickly and hang up or else it will go to zero percent eventually.
if we allowed discharge to 30 percent, then we would be stuck with 30 percent, if 40 percent, etc. So what ever we allow as the lower limit we might end up stuck with that for a while if the power line goes down and of course hopefully the power comes back on soon.
So charging to 80 percent means we are stuck with only 80 percent when we could have gone all the way to 100 percent and killed the battery faster over a year or two.

So i guess the main question then is what to charge too and what to allow as the lower limit before we charge again.
 

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
My solution for a longer battery life is to use the phone as a telephone. I do my internet stuff on a computer where I have a much larger screen and a real Keyboard. I use a good quality camera for my photography. I really don't have to be in touch with social media 24 hours a day. I use my Acer phone in power management mode with all the online applications turned off and blocked. Google is by far the biggest culprit in using your phone's battery. It constantly monitors any activity and stores data and preferences on the cloud and it regularly updates it's self even if you have wifi turned off.
I use my phone as a phone with voice and text, with no access to data. I can still get on the internet with it in a wifi area if I really need to. The service costs a total of $25.00 per month. It lasts an average of eleven days between charges. That will increase the life of the battery by more than five times.
Regards,
Keith
That's an interesting view Use the phone as little as possible.

But i do think that plays in conjunction with the 80 percent max idea. If we do what you do AND we only do 80 percent max, then we get the benefits of both ideas. That's what it seems like anyway.
 

KeithWalker

Joined Jul 10, 2017
596
You don't need to panic about power failures.There are always alternatives available. I keep a couple of power banks charged up for if that happens.
Regards,
Keith
 

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
You don't need to panic about power failures.There are always alternatives available. I keep a couple of power banks charged up for if that happens.
Regards,
Keith
That is probably the better idea yes.
Of course then we run into the issue about how much to charge up the power banks. That's probably not as bad though if they are high powered enough.

But i ran into a secondary issue. My phone will not reset the "time on battery" unless i charge all the way up to 100 percent. That's not a big problem just annoying. I just charged it a little while ago accidentally to 99 percent and now it reads "153 hours on battery power" when really it was just a couple hours now. Apparently i have to go all the way to 100 percent to get it to reset so it reads 2 hours when it really is 2 hours. Unless i can find a way to manually reset it, or get a new app maybe.
Any ideas?
 

rupe01

Joined Oct 15, 2018
16
You would be fine doing the 20% discharge thing if you just had a backup battery bank to plug it in to for emergency. I keep several banks of 1, 2, 4 and 8 18650's for emergency recharging. just one of these available would put your mind at ease to discharge to 20%.
 

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
You would be fine doing the 20% discharge thing if you just had a backup battery bank to plug it in to for emergency. I keep several banks of 1, 2, 4 and 8 18650's for emergency recharging. just one of these available would put your mind at ease to discharge to 20%.
Hi,

Yeah sounds good. I am going to do that.
Plus i realized that it wont hurt to charge it up to 100 percent sometimes when i think a problem might come up or i have to go somewhere that is farther away from home or when i know i will have to use the phone for a longer period of time.

What is different about these phones vs home land line phone is that i always have to think about the charge state, even if i go to 100 percent most of the time. That is a little strange as with the old plug in the wall phones i never had to do that ever. I have a cordless phone too for the land line but that has a charge cradle where i just pop it back in after talking. I could talk for hours on that thing and never worry about the charge state, as long as i put it back in the charge cradle.
The cell phone is a different animal.
 

rupe01

Joined Oct 15, 2018
16
Yep, i agree on the home phone thing as i do the same and mine has lasted probably eight years now.....but thinking about it, i think mine is nickelmetalhydride in mine. Mine hasn't lost a beat in eight years, and i tend to prefer those batteries now i am seeing/finding all the pitfalls in lithium. Newer technology is definitely not always better.
 

gramps

Joined Dec 8, 2014
76
I've had my phone (LG G3) for 4-5 years. I'm not one that needs the latest and greatest every time something new comes out. Anyway, I charge it to 100% every night, and it lasts me all the next day. If/when the battery dies, a replacement is only $20. So what's the big deal? I don't get it.
 

rupe01

Joined Oct 15, 2018
16
I get it.......he is just using it as a challenge to get the best usage from it that he can. It's not about money. Some people solve puzzles, etc.....get it now, hopefully? It's why some people make their own power supply instead of buying from the store.....including me. And yes...my cellphone is over 10yrs old!
 

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
Yep, i agree on the home phone thing as i do the same and mine has lasted probably eight years now.....but thinking about it, i think mine is nickelmetalhydride in mine. Mine hasn't lost a beat in eight years, and i tend to prefer those batteries now i am seeing/finding all the pitfalls in lithium. Newer technology is definitely not always better.
Hi,

Yeah i am finding that new tech is sometimes ever worse than other. But i realized that we cant fit two to four AAA batteries in a phone and have it as slim as the ones we have. Mine is quite thin and the trend now is as thin as possible. So i guess we are stuck with this mess.
 

Thread Starter

MrAl

Joined Jun 17, 2014
6,949
I've had my phone (LG G3) for 4-5 years. I'm not one that needs the latest and greatest every time something new comes out. Anyway, I charge it to 100% every night, and it lasts me all the next day. If/when the battery dies, a replacement is only $20. So what's the big deal? I don't get it.
Hi there gramps,

Well, the big deal is i dont want my phone to catch fire which is what happens when cells like these have problems. I should take some pictures of my swollen battery.
Look around on the web and see what could go wrong with one of these batteries.

But yes part of it is getting long life out of the battery, and this is much much much more important now because the trend now is to have a battery inside the phone which is NOT removable at least not by normal means. For some you have to use a heat gun and go through a lot to get it apart, then have the right glue to get it back together again and hope you get it right.

Lucky my phone is 4 years old and has a removable battery which i can and did replace. My replacement is even cheaper too. I guess i dont mind doing that, but i also dont want to take a chance on having the battery start on fire. When i took the back off the old battery fell right out because it was too swollen to stay in like it should. The swell pushed it right out. That worries me mostly.

Maybe everyone should check their battery at least once per month or something to see if it is swollen.
 
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