Is trickle charging a Lithium Ion battery better than cycling the battery?

Thread Starter

SethB

Joined Mar 30, 2021
28
A little more info:
This is for a phone, specifically a Galaxy S20+ 5G. It is rooted.

I have 2 sysfs files I can control.

/sys/class/power_supply/battery/batt_slate_mode <- allows for complete control over charging

/sys/class/power_supply/battery/hv_charger_set <- sets if the charger is "high voltage"

I've been using this app: GitHub - sriharshaarangi/BatteryChargeLimit to set my voltage between 75 and 80%. The purpose of this is to prolong the battery life as I use Samsung Dex all day (not good to have it plugged in all day). This means when it reaches 80% charging stops. When it hits 75% charging resumes.

If however, I set the "hv_charger_set" value to 0, it basically activates a trickle charge. Whatever percent my battery was at when I set that file value to 0 it will stay at.

So say I hit 80% charge and I set "hv_charger_set" to 0, now all day my battery will be trickle charged and stay at 80%. Watching the charging amps, it basically pulses (almost like PWM) a small current ~9-15mA.

In terms of battery longetivity - which option is better:
1.Turn off charging at 80% and charge at high current from 75% to 80%
2. Turn on a trickle charge at 80% and charge at ~9-15mA all day to maintain the 80%

I have read that trickle charging is not good for the LiOn battery. However, these statements do not fall under my context - battery at 80%. They refer to the battery being at 100%.

I have also read that small currents to the battery are healthier than larger currents.
I also think Samsung engineers are using this trickle charge when the battery is at 100%, as even monitoring sysfs files I do not see the voltage drop.
I have also noticed my phone/battery stays way cooler at the trickle charge, which the general consensus is heat ruins batteries.

As you can tell, I am very confused/torn as to what is "healthiest" for my battery. I keep my phones for about 5ish years and my previous ones have definitely suffered battery life issues. Even if I do get a new phone, I like to keep my current one in pristine condition for the next person.

All advice is greatly appreciated and may ask extra questions to better understand the advice given. Thanks all!
 

MrSalts

Joined Apr 2, 2020
1,762
There are plenty of rumors about lithium batteries and I would be very surprised if Samsung would not control that in software IF keeping the phone fully charged was bad for the battery. Otherwise, I would assume it is not bad for the battery.
There is so much competition for phone battery life and longevity that Samsung would have every motivation to take care of the battery in the phone and they have the software development team to easily do it. So, I doubt you need to buckle to such a rumor about lithium batteries in your phone and the "risk" of keeping it plugged. Where did you hear this rumor about LI batteries?
 

Thread Starter

SethB

Joined Mar 30, 2021
28
There are plenty of rumors about lithium batteries and I would be very surprised if Samsung would not control that in software IF keeping the phone fully charged was bad for the battery. Otherwise, I would assume it is not bad for the battery.
There is so much competition for phone battery life and longevity that Samsung would have every motivation to take care of the battery in the phone and they have the software development team to easily do it. So, I doubt you need to buckle to such a rumor about lithium batteries in your phone and the "risk" of keeping it plugged. Where did you hear this rumor about LI batteries?
Ha. Yeah this is my other debate I have with myself lol. I keep coming back to this too "why even worry about it im sure Samsung engineered it to be fine".

Well, I have a few caveats about that.
1. Samsung wants you to buy their next device. In terms of longevity of battery health, I am sure they don't care. They care about best user experience so if the current goal is 100% battery at all times, regardless of battery health, thats what they will do.
2. I have personally experienced battery health degradation with other LI batteries (laptops) where keeping plugged in all the time absolutely destroys them. They go from like 4 hours to 50 minutes.
3. I have also seen this in my older cell phones. I would get very good battery life at the beginning then it degrades quite quickly prolly because of point # 1

I also have read that LI batteries don't like being at 100% all the time. Even tesla drivers limit to 80%. So I only go to 100% overnight and keep it plugged in until morning. Then I am plugged in while working to keep battery topped up and also for Samsung Dex.

So where I heard these rumors were everywhere. I have found some articles that state charging to 100% is bad because of the chemistry between the ions in the battery and how being at capacity is bad. This is due to the voltage potential being very high. It produces stress if not used immediately on the cells, and the longer its at 100% the more stress it adds to the battery due to the voltage potential driving it to discharge.

Another fact I read about chemistry on LI batteries was the rate at which you charge it. The faster you charge it, the more stress is applied as you are trying to move more particles faster which generates heat and thus shortens battery life.

This leaves me torn as to which to do. I think trickle charge is better as it doesn't cause so much heat to generate. But its also adding more "cycles" to charging. But I have read that a true cycle is at least 30% or more (so it goes from x % + 30% to count as a charge cycle). I also think being at 100% is actually bad due to above mentioned issues - having the voltage potential always high without it being able to discharge.

I think the trickle charge option is the best as it keeps it charged without draining the battery and charges with least amount of heat generation. I would love to get more chemistry based information from everyone tho!
 

MrSalts

Joined Apr 2, 2020
1,762
Samsung wants you to buy their next device.
Yes they do. They also want you to buy their current device and consumers won't if Apple, LG, Google Pixel can say Samsung doesn't take care of your battery if you leave it on a charging stand or plugged in or... c
Conspiracy theories are fun but competition is real.
 

Thread Starter

SethB

Joined Mar 30, 2021
28
Yes they do. They also want you to buy their current device and consumers won't if Apple, LG, Google Pixel can say Samsung doesn't take care of your battery if you leave it on a charging stand or plugged in or... c
Conspiracy theories are fun but competition is real.
Fair point. I just also don't think any of the other competitors care about their devices battery in 2+ years from manufacture. The average phone turn around I think is like 1.5 years for most people. I am too poor lol.
 

MrSalts

Joined Apr 2, 2020
1,762
Fair point. I just also don't think any of the other competitors care about their devices battery in 2+ years from manufacture. The average phone turn around I think is like 1.5 years for most people. I am too poor lol.
First, your assumption is way off - data is easily found. Consumers keep phones average of 2.75 years and broken screen is the biggest reason for replacing a phone. Corporate cell phones are replaced more often but typically because contacts allow a 2-year renewal (average is 2.5 years for business cell phones.
second, you have to look for real data instead of your intuition or reading Facebook stories.
 

Audioguru again

Joined Oct 21, 2019
4,690
Batteryuniversity.com says that a lithium battery at full charge all the time has a short life. The batteries do not want and do not need a "trickle" charge. A Lithium battery is stored and sold at the "storage voltage" of 3.7V to 3.8V instead of at a full charge of 4.2V.
 

Thread Starter

SethB

Joined Mar 30, 2021
28
First, your assumption is way off - data is easily found. Consumers keep phones average of 2.75 years and broken screen is the biggest reason for replacing a phone. Corporate cell phones are replaced more often but typically because contacts allow a 2-year renewal (average is 2.5 years for business cell phones.
second, you have to look for real data instead of your intuition or reading Facebook stories.
Okay so I was off by a year. But yes my data was not taken from "intuition" or "Facebook" stories. It was taken from the fact most carriers offer a new phone free every year. There was a survey done awhile ago I referenced so maybe people keep them longer now because of how expensive they are. My brother himself gets the new iPhone free from T-Mobile every year. Who knows how many others are also on this type of plan or the "Galaxy A year" plan.

Now corporate cell phones I never even thought of. Will admit to that. But still, 2 years is not that long so who cares what sort of damage the battery has.

Batteryuniversity.com says that a lithium battery at full charge all the time has a short life. The batteries do not want and do not need a "trickle" charge. A Lithium battery is stored and sold at the "storage voltage" of 3.7V to 3.8V instead of at a full charge of 4.2V.
Okay. Thank you for this. I guess the trickle charge is not good for it? All I can find regarding the trickle charge at batteryuniversity is about it trickle charging at full capacity.
 

k1ng 1337

Joined Sep 11, 2020
539
When it comes to rechargeable batteries in devices I think you get what you get. Many products fail prematurely because of small manufacturing defects and there is something to be said about how each person treats and mistreats their devices. I venture to say you are probably doing more damage by hacking battery charging in software without hardware considerations of what's already taking place. Like cooling, I've found battery settings to be well managed deep in the system. Unless you have root access you really don't know what's going on and I've caused damage by overriding fans a few times.
 

Thread Starter

SethB

Joined Mar 30, 2021
28
It is rooted
When it comes to rechargeable batteries in devices I think you get what you get. Many products fail prematurely because of small manufacturing defects and there is something to be said about how each person treats and mistreats their devices. I venture to say you are probably doing more damage by hacking battery charging in software without hardware considerations of what's already taking place. Like cooling, I've found battery settings to be well managed deep in the system. Unless you have root access you really don't know what's going on and I've caused damage by overriding fans a few times.
Yeah, I just try to prolong them. Like my laptop battery is already shot after a year. It sits on the charger almost all the time. Manufacturers suck at making them last tbh.

But, yes, It is rooted. And its technically a hardware hack as its changing things inside the kernel of the device. And kernel is king on android lol
 

Audioguru again

Joined Oct 21, 2019
4,690
Of course trickle charging results in a full charge then an overcharge, because the battery keeps charging. It will stay at only 80% if the charging and discharging stop.

A rechargeable Lithium battery cell lasts for a long time when it is at 3.7V to 3.8V. If it is fully charged all the time then it does not last long. a discharge lower than about 3.2V per cell damages it and less than 3V kills it.
 

bassbindevil

Joined Jan 23, 2014
422
I kept my flip phone plugged in 24-7 for about 8 years. The battery was still usable when they shut down the 2G service and I had to get a new phone with a SIM card. So, I'm a bit skeptical that keeping a battery fully charged is really worse than cycling it unnecessarily. The trickle charge should just let the battery float and supplies the current to keep the phone alive..
 

MrSalts

Joined Apr 2, 2020
1,762
I kept my flip phone plugged in 24-7 for about 8 years. The battery was still usable when they shut down the 2G service and I had to get a new phone with a SIM card. So, I'm a bit skeptical that keeping a battery fully charged is really worse than cycling it unnecessarily. The trickle charge should just let the battery float and supplies the current to keep the phone alive..
And you have no way of knowing if the phone is programmed to understand how you use it and it it has been plugged in for the past 24 hours, to "drain the battery to 80% to preserve the battery life". Trying to be smarter than the manufacturers is crazy because there is so much going on in software that you'll never know.
 

Audioguru again

Joined Oct 21, 2019
4,690
Why trickle-charge an expensive battery to reduce its life? Battery makers say to store it at 3.7V to 3.8V then fully charge it before using it. A good Lithium battery charge does not fade away unless a clock or something is draining away the charge.
 

Alec_t

Joined Sep 17, 2013
12,817
A good Lithium battery charge does not fade away unless a clock or something is draining away the charge.
And there's the rub. Phones, like so many modern gadgets, never turn off completely. Even in deep sleep mode there is a tiny current drawn, albeit too small to be worth compensating with a trickle charge. Compensation for phone standby-mode current might be worthwhile though.
 
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