General > General Technical Chat
Extending lithium battery lifespan
(1/4) > >>
Connecteur:
I have very little electronic expertise, but I believe the lifespan of lithium cells can be greatly extended by undercharging.  Conversely, I believe that overcharging shortens their lifespan.  I have replaced 12V batteries with banks of 4 lithium cells in series.  This charges each cell to 3V, well below the nominal full charge of 4.2V.  I expect such a battery of cells will last many years.

I had the Battery in my Samsung S9+ blow up before it was 2 years old. What I mean is that the battery expanded and pushed the backplate off. I found out it's because the battery gets charged to 4.4 volts, which increased capacity marginally, but reduces battery longevity considerably.

After some research, I learned that charging a lithium cell to 85% will extend it's lifespan by 210%. The small decrease in capacity is little concern to me. I have 2 Samsung tablets with the same operating system as the phone, and one of the options is to charge the battery to only 85% to extend battery longevity. There is no such option on the Samsung phone. Why not? It's easy to assume that it's to make the phone fail after a year so that you'll buy a new one.

There is no app that will stop the phone from fully charging to 100% (4.4 V) but there is an app that will sound an alarm when it reaches a predetermined level. I've been using it since I had to pay a hundred bucks for a new phone battery to be installed.

Am I on the right track?
tunk:
For most li-ion/li-po cell, 3.0V is fully discharged.
And that overdischarging them is detrimental to their life.
I guess you could charge them to 4.0V and discharge them
to 3.2V.
Siwastaja:
Not on a very good track so far but you'll get there...

First, lithium batteries as of today are non-rechargeable. There are chargeable lithium cells but they are niche / development / lab products and unusable in real world so far.

So we have to assume you are talking about lithium ion cells, completely different animal.

Then, "charging to 3.0V" would not make sense with the most prevalent LCO, NCA, NMC, LMO, LFP chemistries since on all of them, 3.0V is completely discharged. So maybe you are discussing lithium titanate oxide cells such as Altair Nano? But here, full charge is at 2.9V so 3.0V is already slightly overcharged. So this 3.0V thing just doesn't make any sense.

Assuming you are indeed discussing the most typical li-ion cells of today, that would be NCA or NMC, idea of derating capacity to 85% bringing you 210% extra lifespan is iffy. Yes, if you consider high-current cycling up to 100%, that could be a case in some carefully crafted test, but you could get similar lifespan improvement by just charging more slowly from 85% to 100%. Calendar fading at 100% and 85% is possibly the same; it depends, some cells get improvements, some others don't. Usually you start seeing significant results below some 70%.

It's possible the other Samsung phone doesn't have the 85% option because on that cell chemistry, there just is no difference, or they have made other "automatic" improvements (like finding out by testing what I did years ago; just limit current a tad near 4.2V!) Another possibility is, there is difference but they want to play the planned obsolescence game.

I don't believe any tablet uses chemistry where 100% charge is at 4.4V, but I might be wrong.
GigaJoe:
percentage of charge indicated on a device in direct correlation with impedance of battery.   fully charge level usually depend on battery chemistry and can be from 3.70 to 4.35V .   it probably 30+  variation of chemistry compound in overall , only few in mass production.  measure precise fraction are important, like 4.31V still has a percentage of let say 3.35V   top level.     (it means need at least 4.XXX on measurement device display, not 4.X - too uncerain )

usually it a single chip that responsible for charging , type and top voltage correlated to battery chemistry.
it possible that chip out of spec tolerance, or it shifted in time, so charging process are incorrect. ( we deal with 4.XX precision)

longevity of battery directly depend on charging cycles , charge \ discharge level,   usage temperature.

amount of charging cycles usually limited by 300-400 full cycles ,   till battery lost 30-40% of capacity.  with fraction of cycles , let say from 30% to 80%  it can be even extended to 1000

charging current usually play the most role in longevity, so would be advisable do not use fast charging , or disable it. 
but it direct correlation with battery capacity. so large tablets due to large battery capacity , and surface  much more tolerable to the high current.

temperature also factor that can be overlooked, due to charging cycle it produce a heat that need to dissipate , do device pass the heat over the shell to the surface table cooling itself, but if it in enclosure it more difficult. so internal temperature are rising.

personally I.m use 5v 0.5A charger   over night   (or 5V 1A charger with long cheap cables)   my S8 usually shows 4 hours to full charge. so current and temperature artificially limited.   I don't bother to charge up to 90% - not big deal .    but in extremely caution do not discharge below 20%,  usually 30% - set to charge.

my tablet has magnet connector,  it also limit current

duckduck:
I used to set a timer for 30 minutes or whatever on my phone to beep to remind me to pull the phone off of the charger. I bought one of these and it works well. It's a little annoying to use, but I can set it and forget it. Search for "USB timer" or similar. I thought of making my own thing, but Shenzhen does it cheaper...
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod