White Light of Death?

[Skull One]

Would you be so kind and please explain the discrepancy between the two following post.

On May 22nd 2012 (yesterday) you posted the following information to prove your point.

Trash Can is 100% correct. For example, it is better to charge from 20% to 60% and then again from 20% to 60%, rather than from 20% to 100%. Shorter charges, on average from 25% to 75% of capacity will extend the battery's total life from 500 100% charges to as much as either 1,000 75% charges or 1,500 50% charges (each yielding 750 100% charges) or to 2,500 25% charges (yielding 625 100% charges).

Based on those numbers, it looks like the "sweet spot" is somewhere near or between 50% and 75% per charge. This falls right in line with the manufacturer's recommendation that you place the phone on charge as soon as the "Low battery" warning signals at 15%, and that the phone will maintain a full charge at somewhere between 90% and 100% of rated capacity (15% reserve plus 10% cushion = 25% variance against capacity, leaving 75% charge in the cycle).

On March 25th 2012 you PASTED the following information from Battery University to prove your point. (source http://www.droidforums.net/forum/dr...ery-dead-all-you-naysayers-3.html#post2062430)

There is information that indicates you can extend the life of a Lithium Ion Polymer battery by charging more frequently and not charging long and full charging cycles as a habit.

This information is from BatteryUniversity.com

Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses. If full discharges cannot be avoided, try utilizing a larger battery. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery.
Table 2 compares the number of discharge/charge cycles a battery can deliver at various DoD levels before lithium-ion is worn out. We assume end of life when the battery capacity drops to 70 percent. This is an arbitrary threshold that is application based.

Depth of discharge​	Discharge cycles​	Table 2: Cycle life and depth of discharge A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents also affect cycle life.
100% DoD​ 50% DoD​ 25% DoD​ 10% DoD​	500​ 1500​ 2500​ 4700​

Specifying battery life by the number of discharge cycles is not complete by itself; equally if not more important are temperature conditions and charging voltages. Lithium-ion suffers stress when exposed to heat and kept at a high charge voltage.

By looking at the chart, it seems the sweet spot, or most life overall is achieved by charge cycles that are close to 50% of capacity on average (50*1500=75,000), versus 100% charge cycles (100*500=50,000). I would have liked to see the chart extended into 10% ranges but it also proves that 25% charges and discharges also provide a longer life than 100% charge cycles (25*2500=62,500), so it is safe to assume that charging somewhere between 25% and 75% as regular cycles on average is likely to be yielding the best overall performance over life.
​

Do you see the contradiction? If not let me explain what I see in regards to your posts.

Depth of Discharge is the depletion of the electrons or "stored energy" in a Lithium-Ion battery. Using that chart, that you posted no less, if you take the battery from a 100% charge to 0% charge, you will be able to "on average" do 500 full charges. And at the end of that time frame, you will have a battery that will be able to maintain 80% of the original potential storage capacity of the battery when it was original constructed. Per the current specification of consumer grade Lithium-Ion batteries.

The next line shows that if you go from 100% charge and then DISCHARGE the battery to ONLY 50% and then recharge it back to 100% you will be able to on average perform 1500 of those recharges. And again at the end of that time frame you will have a battery that is capable of maintaining 80% of the original potential storage.

The next line shows that if you go from 100% charge and then only discharge to 75% charge that you will, again on average, be able to charge the battery 2500 times.

100% down to 90% execrate execrate...

That Depth of Discharge chart specifically show that by only going from 100% down to 50% and NOT BELOW that point of discharge that you have the potential to maximize the performance of the battery. The reason for that is very CLEAR based on the chart you having been pasting.

That chart shows as you approach 100% charge the amount of amperage (the dashed line) used to charge the battery is reduced. It is done that way to help prolong the life of the battery by placing LESS STRESS on the chemical compound in the battery and to also help avoid any potential plating of the Anode. Lets leave RC cars out of the discussion, it only clouds the issue and isn't relative to my points.

So by using your own posts and then PROPERLY interpreting the data it shows you don't ever want to get below the 50% charge level to get maximum usage from the battery. So your suggestion that you want to charge from 20% up to only 60% and repeating that habit flies directly against the VERY DATA you posted as FACT. Because from 20% to 60% you will be in the FULL 100% amperage charging rate the entire time vs the 50% to 100% in which you will only be in the full 100% amperage range for 70% of the charge. And hence why I suggested they should only discharge to 60% because then you are only in the full 100% amperage charging rate for 62.5% of the time.

These are your posts and your reference material. Why have you posted conflicting information?

 

[cereal killer]

Hello gentlemen! Great topic and info!! Just a friendly reminder to keep the debate civil and definitely keep the info flowing. Thanks guys!!

 

[thaDroidz]

Hello gentlemen! Great topic and info!! Just a friendly reminder to keep the debate civil and definitely keep the info flowing. Thanks guys!!

Battle of the really long replying battery gods!


I have great respect for both of these "dudes" just poking fun

----posted MAXXED OUT WITH dessert----

 

[cereal killer]

Moved to new forum!!!

 

[FoxKat]

Would you be so kind and please explain the discrepancy between the two following post.

On May 22nd 2012 (yesterday) you posted the following information to prove your point.




On March 25th 2012 you PASTED the following information from Battery University to prove your point. (source http://www.droidforums.net/forum/dr...ery-dead-all-you-naysayers-3.html#post2062430)



Do you see the contradiction? If not let me explain what I see in regards to your posts.

Depth of Discharge is the depletion of the electrons or "stored energy" in a Lithium-Ion battery. Using that chart, that you posted no less, if you take the battery from a 100% charge to 0% charge, you will be able to "on average" do 500 full charges. And at the end of that time frame, you will have a battery that will be able to maintain 80% of the original potential storage capacity of the battery when it was original constructed. Per the current specification of consumer grade Lithium-Ion batteries.

The next line shows that if you go from 100% charge and then DISCHARGE the battery to ONLY 50% and then recharge it back to 100% you will be able to on average perform 1500 of those recharges. And again at the end of that time frame you will have a battery that is capable of maintaining 80% of the original potential storage.

The next line shows that if you go from 100% charge and then only discharge to 75% charge that you will, again on average, be able to charge the battery 2500 times.

100% down to 90% execrate execrate...

That Depth of Discharge chart specifically show that by only going from 100% down to 50% and NOT BELOW that point of discharge that you have the potential to maximize the performance of the battery. The reason for that is very CLEAR based on the chart you having been pasting.

That chart shows as you approach 100% charge the amount of amperage (the dashed line) used to charge the battery is reduced. It is done that way to help prolong the life of the battery by placing LESS STRESS on the chemical compound in the battery and to also help avoid any potential plating of the Anode. Lets leave RC cars out of the discussion, it only clouds the issue and isn't relative to my points.

So by using your own posts and then PROPERLY interpreting the data it shows you don't ever want to get below the 50% charge level to get maximum usage from the battery. So your suggestion that you want to charge from 20% up to only 60% and repeating that habit flies directly against the VERY DATA you posted as FACT. Because from 20% to 60% you will be in the FULL 100% amperage charging rate the entire time vs the 50% to 100% in which you will only be in the full 100% amperage range for 70% of the charge. And hence why I suggested they should only discharge to 60% because then you are only in the full 100% amperage charging rate for 62.5% of the time.

These are your posts and your reference material. Why have you posted conflicting information?

Sure Skull One, I'd be happy to clarify. I believe you and I are not far apart in our beliefs but perhaps there is a major and distinctive divergence in interpretation of the data and that is the root of our differences. It's easy to clean this up from my point of view. I'll address them now.

Originally Posted by FoxKat
​

Trash Can is 100% correct. For example, it is better to charge from 20% to 60% and then again from 20% to 60%, rather than from 20% to 100%. Shorter charges, on average from 25% to 75% of capacity will extend the battery's total life from 500 100% charges to as much as either 1,000 75% charges or 1,500 50% charges (each yielding 750 100% charges) or to 2,500 25% charges (yielding 625 100% charges).

Based on those numbers, it looks like the "sweet spot" is somewhere near or between 50% and 75% per charge. This falls right in line with the manufacturer's recommendation that you place the phone on charge as soon as the "Low battery" warning signals at 15%, and that the phone will maintain a full charge at somewhere between 90% and 100% of rated capacity (15% reserve plus 10% cushion = 25% variance against capacity, leaving 75% charge in the cycle).​

First, I don't see the "conflicting information" you indicate and question. In both posts, I maintain the same position which is that it is better to operate the battery in the middle of the charging range rather than either in the top or bottom ranges. The ONLY difference I see is the mention of the sweet spot being between 50% and 75% of charge in one and between 25% and 75% in the other. The difference is only because in the 50% to 75% range post I was using the actual posted data on the chart, and the other post I was iteratively extrapolating a wider hypothetical range based on the factors at the lower end of charge depletion.

The above information is based on the chart as you mentioned, and also on additional information provided in the plethora of data on the BatteryUniversity.com website (as well as a myriad of other sites I visit, books I've read, magazines I subscribe to, etc., but I kept it to BatteryUniversity.com for simplicity). The key issues are as follows:

Charging in the low range of the charge capacity, or in other words in the range not near 100% of usable capacity, but perhaps staying in the lower 80% comes from the results of the chart first, but also other text I will follow with. The chart must be understood completely to extract the accurate conclusion. The Depth of Discharge (DoD) is as you say a reference to how much you come off of the 100% of usable capacity mark - let's call it a full charge to 100%. So a DoD to 50% would be using 50% of the 100% full charge, the same as 50% remaining. This seems quite obvious and it is. So therefore, a DoD of 25% would indicate a remaining charge of 75%, right? Right.

Now, what we also have to understand is the number of cycles in that chart is NOT the number of 100% charge cycles on every line, but ONLY works out to be so on the 100% DoD line. It is actually referencing the number of charge cycles at the percentage required to replenish the DoD referenced on that line, so for example, in the case of a 50% DoD, it says you will get 1500 cycles, however that's 1500 50% cycles, which if you do the math is equivalent to 750 100% cycles. So it's fairly safe to say that if you maintain a DoD cycle pattern of 50%, you will gain about 50% of expected battery life (500 100% cycles versus 750 100% cycles, or 250 more 100% cycles against the original 500, or 50% more life).

So it seems that the chart indicates that with less and less DoD cycles (10% versus 25%, 50% or 100%), that you will get "more and more" life out of the battery. Unfortunately it will lead you to that belief if you don't do the math. As it is clear now, 500 cycles in the case of the 100% DoD (500 100% cycles) is actually a LONGER battery life than 4700 cycles in the case of the 10% DoD (470 100% cycles). That single piece of evidence is perhaps the most overwhelming evidence that proves my claim from the beginning and proves I have been 100% correct all along.

Also, expected battery life (or end of usable life) is different depending on which manufacturer you talk to. You mentioned 80% as the expected "end of life" (*and that may be what Motorola chose - though I don't know*), but for this chart, it isn't 80% of original rated capacity (capacity when it left the factory), but is 70% of original rated capacity as written in the text accompanying the chart "We assume end of life when the battery capacity drops to 70 percent. This is an arbitrary threshold that is application based.". So with 50% DoD cycles, you're getting 750 100% charges that start out with the battery being able to hold a charge which is 100% of original rated capacity, and decrease gradually as the capacity of the battery diminishes, and ends in the 750th cycle with the battery being able to hold only 70% of the original rated capacity, so in that example in that last 100% cycle you're getting a 100% charge cycle of the now reduced 70% of original rated capacity.

Now let's look at why it's better to remain in the lower charging range rather than the upper. In the chart, it says that a 100% capacity DoD cycle will yield 500 cycles. It also says that a 25% DoD cycle will yield 2,500 cycles. What we have to first do is convert the number of cycles at that percentage of DoD to a common percentage, so using 100%, we can compare against 100% DoD cycles. To do that, a DoD of 25% means that it takes 4 25% DoD to equal 1 100% DoD. So dividing 2,500 by 4 gives you a result of 625, meaning 2,500 25% DoD cycles will yield the effective capacity of usable charge as would 625 100% DoD cycles. So yes, only discharging to 25% DOES yield a longer battery life than discharging to 100%, in fact a 25% longer life. So this seems to prove what you said earlier - that maintaining the charging in the top of the charge cycles (and with the top 10% being at the lower "saturation current" or "Stage 2") is better for the battery.

But what you're missing here is that if that were an accurate indication of the beginning point of a trend at the top end, and using the known 100% DoD number of 500 cycles as the truly accurate indicator of the end point, then going to a 50% DoD would yield somewhere in between, and LESS net 100% charge cycles than 25% DoD, and in fact it's not so. The 50% DoD cycle actually yields 1,500 50% cycles, and since it takes 2 50% cycles to equal 1 100% cycle, you divide 1,500 by 2 and you get 750...750 100% cycles.

But wait...let's try to disprove what I've just said by looking at 10% DoD cycles...surely 4,700 10% cycles should prove me wrong, especially if your claim of Stage 2 charging being LESS stressful on the battery than Stage 1 charging is accurate, right? Well, if it takes 10 10% cycles to equal 1 100% cycle, then dividing 4,700 by 10 results in 470 100% cycles - which is LESS than the 500 100% cycles at a 100% DoD. This means your battery will last LONGER if charged to 100%, discharged to 0% and then charged to 100% again every time, than it will if charged to 100% and discharged to 90%, and then charged to 100% again...the top 10% of the charge cycle...the Stage 2 that you were saying is the LEAST detrimental to the battery. It is also LESS than the 750 100% cycles at 50% DoD, and even LESS than the 625 100% cycles at 25% DoD.

100% DoD = 500 100% cycles, which = 500 100% cycles

50% DoD = 1,500 50% cycles, which = 750 100% cycles (the sweet spot begins somewhere between 100% DoD and 50% DoD, so I used 75% DoD as a crude interative guess - see below)
25% DoD = 2,500 25% cycles, which = 625 100% cycles (and continues here)
10% Dod = 4,700 10% cycles, which = 470 100% cycles (and drops off to below 100% cycles here)

75% DOD = a hypothetical 1,000 75% cycles, which = about 750 100% cycles

So, to reiterate, your battery will last longer if you do NOT charge to 100% with each charge, and instead remain in the range of between a 25% charge and a 75% charge (as a hypothetical upper limit). In other words, it's not whether you are charging in Stage 1 or Stage 2, but whether you are keeping the battery at or close to its maximum charge capacity over either longer or shorter segments of time for each charge cycle.

The real upper limit which might get us to lets say 625 100% cycles (giving us a range from 625 to 750 100% cycles across the major middle of the charge cycle) may actually be 80%, or it might be 85%, but it is definitely going to be a lower number of cycles as you approach the top 100% of the charging cycle range as these numbers clearly indicate (470 100% cycles at 10% DoD). This is why I indicated it would have been helpful to see 10% increments across the entire range. 5% increments would have been even more revealing but perhaps overkill.

By the way, the example above is what is known typically as a "Bell Curve" where the worst performance is at the tops and bottoms of the ranges, or at the leading and following edges of the bell, and the best will be somewhere in the middle of the range as identified by the top of the bell. When they engineer batteries, they do so with a "range" of "typical" use and that range is where they target the best performance. In the case of batteries in cell phones, on average, the greatest percentage of batteries spend the greatest percentage of their charge range in the MIDDLE of the range, not at either the top or the bottom, so it only makes sense that if you want the best performing battery for those ranges, you would want a battery that lasts longest if charged between 25% and 75% of the entire range most of the time (the major portion of the bell curve - the middle)

Now to further bolster my claims (not that the data doesn't already irrefutably prove them), here's a couple more quotes from BatteryUniversity.com;

"Lithium-ion does not need to be fully charged; a partial charge is better."
Interpretation...a partial charge is better than a full charge (not that a partial discharge is better than a full discharge), or in other words, its better to NOT charge to 100%, no matter whether you are using 10% in each DOD cycle or 75%. So doing 25% cycles, if starting at 75% charge level, decreasing to 50%, and then charging back to 75% WOULD yield better results than 25% cycles starting at 100%, decreasing to 75% and charging back to 100% and the chart proves it. Furthermore, doing 25% cycles starting at 60% and decreasing to 35% is also likely going to yield better results than 100% to 75% and back, since even 100% cycles outperforms 10% cycles, which also disproves the Stage 1 versus Stage 2 theory that Stage 2 charging is less stressful than Stage 1 charging when all other factors are considered.

Another quote to prove the above paragraph;

"Li-ion does not need to be fully charged, as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge, because high voltages stresses the battery. Choosing a lower voltage threshold, or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime."

Eliminating the saturation charge altogether, prolongs battery life...that means if I ONLY charge in Stage 1 to 90% of usable current capacity and never actually go to a Stage 2 charge for the last 10%, I will extend the life of my battery! So again, completely proves my point and completely disproves yours.

And yet another quote;

"Avoiding full charge has benefits, and some manufacturers set the charge threshold lower on purpose to prolong battery life."

So what they're doing here is essentially "Eliminating the saturation charge altogether", or eliminating Stage 2 of the charging cycle.

Now, another comment you made which had me a little baffled is "depletion of the electrons or 'stored energy'". In a battery the electrons are neither depleted during discharge, nor are they replenished during recharge. The law of conservation of energy is a law of physics. It states that the total amount of energy in an isolated system (read sealed Lithium battery) remains constant over time. The total energy is said to be conserved over time. For an isolated system, this law means that energy can change its location within the system (move between Anode and Cathode, and that it can change form within the system, for instance chemical energy can become kinetic energy, but that energy can be neither created nor destroyed.

In the case of a Lithium battery, during charge and discharge, ions move between the cathode (positive electrode) and the anode (negative electrode). During discharge, the anode undergoes oxidation, or loss of electrons, and the cathode sees a reduction, or a gain of electrons. Charge reverses the movement. In other words, the net effect is the electrons are simply shifted from the cathode to anode and back again (through the charging or discharging circuit).

The number of "free electrons" in a battery is determined NOT by how much it's charged, but by the chemistry of the battery internally. All charging does is cause an electrochemical reaction (or in the case of Lithium Ion batteries, an Ionization reaction), which releases electrons from their bond with or near either the anode or cathode and causes them to move freely to the opposite pole through the "closed circuit" outside the battery. The only time electrons actually leave the battery is during charge or discharge, and they are never "depleted". Every electron that leaves the negative terminal of a battery is replaced by an electron at the positive terminal, so it's not a depletion of electrons, but an exchange of electrons that creates the flow.

The reason a battery will eventually take less of a charge is NOT due to electron depletion but due to electrons becoming trapped at either the Anode or Cathode due to the breaking down of the internal battery chemistry, the loss of electrolyte (Lead Acid), increasing of internal resistance, the buildup of crystals in the electrolyte (Nickel Cadmium), plating if the anode with metal (Lithium) or any other number of internal electrochemical causes, but NOT due to "depletion of electrons".

To summarize...

The overriding debate here was whether using the top of the charge cycle as the basis for power (90% to 100% of usable capacity), or anything under that (the 0% to 90% portion of the usable capacity) would either extend or shorten the battery's life. It has been proven here beyond a shadow of a doubt that operating a battery in the top range of charge is detrimental to the lifespan of the battery and that by operating in a range between perhaps 25% and 85% of the total usable capacity of the battery will in fact extend its lifespan. There is plenty of third party evidence to corroborate that claim:


"Avoid charging to 100% capacity. Selecting a lower float voltage can do this. Reducing the float voltage will increase cycle life and service life at the expense of reduced battery capacity. A 100-mV to 300-mV drop in float voltage can increase cycle life from two to five times or more."

"Use partial-discharge cycles. Using only 20% or 30% of the battery capacity before recharging will extend cycle life considerably. As a general rule, 5 to 10 shallow discharge cycles are equal to one full discharge cycle. Although partial-discharge cycles can number in the thousands, keeping the battery in a fully charged state also shortens battery life."

"With present battery technology and without increasing battery size, you can’t get both longer run-time and longer battery life. For maximum run-time, the charger must charge the battery to 100% capacity. This places the battery voltage near the manufacturer’s recommended float voltage, which is typically 4.2 V ±1%. Unfortunately, charging and maintaining the battery near these levels shortens battery life."

(ref: http://lancair.net/lists/lml/Message/56976-02-B/Li-Ion Battery Life.pdf)

"* partial-discharge cycles can greatly increase cycle life, and charging to less than 100% capacity can increase battery life even further."

(ref: Increase Your Battery Life / Save Your Time)

"Avoid full charging when you can."

"For pure electric vehicles, avoid deep discharging your battery pack."

(ref: Eight tips to extend electric vehicle battery life)

"Avoid full charging when you can.
One reason that batteries in mobile devices only last a couple years is that they are being pushed to their maximum capacity—frequently getting fully charged and fully drained. Consumer products are advertised by their battery operation time, not their battery lifespan. This means that every possible electron will be shoved in there. Charging to maximum capacity might give you the most possible use for that one charge, but it is one of the worst things that you can do to lithium batteries.

In the 2011 Nissan LEAF, there is a Long Battery Life setting that tells the car to stop charging at 80 percent. This reduces the available range, but could greatly increase the lifespan of your battery pack. If your normal daily driving can be done with less than an 80 percent charge or you can charge mid-day, this simple setting is one of the easiest things that you can do to increase the battery’s lifespan.

One additional advantage of not charging up all the way is that it leaves room to store energy from regenerative braking. Often when the batteries are full or near full, regen will be disabled to avoid overcharging the batteries.

Avoid deep discharging your battery pack.
Lithium-ion packs prefer a partial cycle rather than a deep discharge. Since lithium-ion chemistries do not have a memory effect, there is no harm using a partial discharge. Not only will this avoid excessive wear, it will also mean that—with a little planning—you will arrive at your destination with range to spare."

(ref: Eight Tips to Extend Battery Life of Your Electric Car | PluginCars.com)

"Standard mode charges bring the battery up to 80-86% and only allows it to discharge down to 20%. So that's closer to the 50% sweet spot the battery cells like."

(ref: Charge in Standard, Drive in Range)

If you need additional references to further bolster my claims please PM me out of respect for the rest of the forum members. And as a side note, lets try to focus the balance of our future combined knowledge and energies on helping others and not on trying to prove each other wrong.

 

[Skull One]

Thank you very much for that novella. It finally allowed me to see why you are posting the type advice that you are. And I must say if cell phones ever start using "commercial grade" Lithium-Ion battery packs, your advice will be invaluable and even I will follow it to a "T".

But at present cell phones are using "consumer grade" single cell 4.2V Lithium-Ion batteries. Now to be fair, your advice will in fact allow the battery to "chemically" last longer. It will take the average life of 2 to 3 years and extend it out to probably 8 to 10 years. If, and this is a BIG IF, the user doesn't charge the battery frequently. But because your advice never allows the battery to reach full saturation, the 25% to 75%, you suggested, operational range provides a very fixed amount of milliamp hours of usage. This in turns leads to more frequent charging cycles being required. And this is where you advice actually causes a major issue and can cause the battery to fail much sooner than your advice intended.

Now to explain this I actually have to bore the general audience with some chemistry. But the side benefit is, it will help you understand why I used the shortened phrase 'depletion of the electrons or "stored energy"' that you took issue with. The proper version of that is technically 'depletion of the electrons potential or "stored energy"'. I apologize for dropping that word out. At the time I didn't think it would be needed. But alas it now is. BTW; my memory is a little rusty on this so forgive me if I gloss over some of the finer points. It has been over 26 years since I did serious chemistry work.

One of several Lithium salts compounds, decided on by the manufacturer of the battery, are used as the basis for making a Lithium-Ion battery. The basic pretense is to use an electrical current to pass thru a piece of graphite combined with a Lithium substrate to starts a chemical reaction with the Lithium salt compound. This electrical current causes the outer electron shell, the valance electrons, of the Lithium substrate to become "excited". These valance electrons basically start looking around for other elements to bond with. The stronger the current to the battery, the faster the Lithium valance electrons pick up the current or charge. This then starts the chemical reaction of bonding with the Lithium Ion salt. Now the new chemical compound that is created is not technically "stable". If it was, then we would never be able to get the stored energy back out. So as soon as we put this battery into a circuit it does it very best to release the stored energy by reversing the process. And hence why I used the phrase I did. The electrons potential is passed from wall charger to the battery and then finally to the device.

Now during that process is where your advice has the very serious potential to cause a major problem to a "consumer grade" battery. BUT I freely admit is 100% applicable to "commercial grade" Lithium-Ion batteries.

This entire chemical process has a "bad" side effect. While the charging cycle is occurring, the graphite and lithium substrate expand in size. And as soon as we remove the charging current it contracts back to its normal "at rest" size. If that expansion and contraction occurs enough times, you will crack the graphite. Once the graphite becomes damaged, you can no longer charge the battery.

Now the Depth of Discharge chart is based on the Lithium Salt chemically changing state over time , IE why 500 full cycle charges and you end up with less storage capacity. So your advice is some what spot on that regards. You are trying to prolong the Lithium Salt compound. But your advice accelerates the demise of the graphite.

Also the amount of current directly correlates to the expansion of the graphite and lithium substrate. So the four stage charging chart can now be used to show how we can reduce the damage to this critical graphite. As the current drops the graphite shrinks back to normal size. And physically you always want to slowly allow graphite to return to its normal "at rest" size vs what you suggest which is cutting off the current while still in Stage 1 and at 100% amperage. You are basically introducing the worst case scenario to the graphite.


I apologize for not stating any of this sooner, but to be blunt, I didn't realize you were applying "commercial grade" advice to "consumer grade" single cell batteries till now. Plus I thought you would have known all of this based on the amount of data you had been referencing.


So to wrap this up, the average consumer, should probably stick with the general advice I have been giving for years. Let the battery discharge to 40% and then recharge back to 100%. Try to do it only once a day and the battery will last for the two years you own the device.

 

[FoxKat]

OK, so it seems as I said before that you and I aren't really all that far apart in our opinions. More like two trains on parallel tracks, just waiting for the opportunity to make the switch as it were! :biggrin:

I also appreciate you recognizing that my advice, and my interpretation of the data are accurate (whether the question of consumer versus commercial batteries applies or not is of question, but just the same...)

I have done extensive research not just in commercial grade batteries, but also in consumer grade - in fact MOST of the education I have is in consumer products, so the batteries are therefore typically also consumer grade.

I can provide reference after reference of the manufacturers of consumer products (which contain consumer grade LI or LIPO batteries) and in virtually every instance there are two key pieces of advice provided.

• Use partial-discharge cycles Using only 20% or 30% of the battery capacity before recharging will extend cycle life considerably. As a general rule, 5 to 10 shallow discharge cycles are equal to one full discharge cycle. Although partial-discharge cycles can number in the thousands, keeping the battery in a fully charged state also shortens battery life. Full discharge cycles (down to 2.5 V or 3 V, depending on chemistry) should be avoided if possible.
• Avoid charging to 100% capacity Selecting a lower float voltage can do this. Reducing the float voltage will increase cycle life and service life at the expense of reduced battery capacity. A 100-mV to 300-mV drop in float voltage can increase cycle life from two to five times or more. Li-ion cobalt chemistries are more sensitive to a higher float voltage than other chemistries. Li-ion phosphate cells typically have a lower float voltage than the more common Li-ion batteries.
  
  
  Most Li-ion manufacturers have set a 4.2-V float voltage as the best balance between capacity and cycle life. Using 4.2 V as the constant voltage limit (float voltage), a battery can typically deliver about 500 charge/discharge cycles before the battery capacity drops to 80%. One charge cycle consists of a full charge to a full discharge. Multiple shallow discharges add up to one full-charge cycle.
  Although charging to a capacity less than 100% using either a reduced float voltage or minimum charge-current termination will result in initial reduced battery capacity, as the number of cycles increases beyond 500, the battery capacity of the lower float voltage can exceed the higher float voltage. Fig. 3 illustrates how the recommended float voltage compares with a reduced float voltage with regard to capacity and the number of charge cycles.
  
  View attachment 50371
  
  
  Because of the different Li-ion battery chemistries and other conditions that can affect battery life, the curves shown here are only estimates of the number of charge cycles and battery-capacity levels. Even a similar battery chemistry from different manufacturers can have dramatically different results due to minor differences in battery materials and construction methods.
  Battery manufacturers specify a charge method and a float voltage the end user must use to meet the battery specifications for capacity, cycle life and safety. Charging above the recommended float voltage is not recommended. Many batteries include a battery-pack protection circuit, which temporarily opens the battery connection if the maximum battery voltage is exceeded. Once opened, connecting the battery pack to the charger will normally reset the pack protection. Battery packs often have a voltage printed on the battery, such as 3.6 V for a single-cell battery. This voltage is not the float voltage, but rather the average battery voltage when the battery is discharging.
  
  
  [h=2]Run-Time Versus Battery Life[/h] With present battery technology and without increasing battery size, you can't get both longer run-time and longer battery life. For maximum run-time, the charger must charge the battery to 100% capacity. This places the battery voltage near the manufacturer's recommended float voltage, which is typically 4.2 V ±1%. Unfortunately, charging and maintaining the battery near these levels shortens battery life. One solution is to select a lower float voltage, which prohibits the battery from achieving 100% charge, although this would require a higher-capacity battery to provide the same run-time. Of course, in many portable products, a larger-size battery may not be an option.
  
  
  Also, using a C/10 or C/x minimum charge-current termination method can have the same effect on battery life as using a lower float voltage. Reducing the float voltage by 100 mV will reduce capacity by approximately 15%, but can double the cycle life. At the same time, terminating the charge cycle when the charge current has dropped to 20% (C/5) also reduces the capacity by 15% and achieves the same doubling of cycle life.
  
  
  

(ref: Proper Care Extends Li-Ion Battery Life)

There was also a Figure 2, which is a very good representation of the same information, so I'll include it here. It clearly shows that by reducing charge to levels below what is suggested at being 100% of usable capacity, you will substantially increase the cycles of charge and therefore increase the battery's lifespan. However at the bottom of the curve, the benefits begin to be outweighed by the number of cycles, so the end result is it becomes more efficient to do 100% charge cycles than 10% cycles. That was the impetus for my "novella" earlier. See figure 2 below:

View attachment 50372

All the chemistry you explain is very interesting and I am sure is also truly quantifiable in the lab, but in the consumer market, the manufacturers - the good ones (as said before) take into consideration real-world scenarios when developing their products, and battery life is such a hot topic (as in this debate), that they are forced to spend inordinate amounts of time, energy, money and research to develop a system that works best under most typical scenarios.

I think we'll have to agree to disagree with your recommendation from my point of view. The consumer was never expected to limit their use to only the top 20% to 30% of the charge cycle as you recommend, and it would cramp the style of the greatest percentage of consumers, such that either they would not buy the product or the manufacturers would suffer immense warranty claims for failure of the consumer to charge the phone when it reaches 60%. Just the very facts that the manufacturer places a warning on the screen at 15% (not 60%) to charge the battery, and that the battery is allowed to float down to 90% after the saturation charge before it once again starts a Stage 2 charging cycle to boost the battery back to 100% are evidence enough that the manufacturer recognizes that both keeping and using the battery in the top 10% range is less important (actually stressing the battery further and reducing its lifespan), that using it in the 15% to 90% range is of the utmost importance, and that using it anywhere in between those two (where it is likely most used) will result in the greatest longevity for the battery and the best user experience.

YRMV :biggrin:

 

[Skull One]

Your further clarification is spot on with trying to preserve the integrity of the Lithium Ion salt. No doubt in my mind what so ever. And I agree with you 100% that should be a consideration. But the Lithium-Ion batteries currently being used in cell phones are under "high pressure" chemically compared to commercial grade which are generally under "low pressure". That is why you also have to take into account the physical properties of the graphite, its natural expansion when placed under an electrical current and it resultant contraction when that current is removed. It's like taking a piece of paper and repeatedly folding it. It will tear. It isn't a matter of if, it is simply a matter of when. So I always tailor my advice to the item that is basically the most critical path to failure. In this case, the high pressure batteries we use make the graphite protection the priority in my opinion.

The good news is, I think between the two of us we covered just about every aspect of Lithium-Ion batteries. Which means the readers now have enough knowledge, without spending days reading very very very (LOL) dry material, to make an informed choice on how they want to use their battery and extend its usefulness.

On a side note, if they ever get silicon* to work instead of graphite/carbon, both of our opinions get thrown right out the window! ROTFL.


*Currently silicon is expanding at up to 400% of its at rest size. While the silicon doesn't crack like graphite, the Lithium the silicon is supporting does still crack. But I believe they are very close to making a break thru on all the issues. Which means we will have batteries that will go from 500 deep cycle charges to well over 5000 deep cycle charges. Basically, a game changer for consumers.

 

[cereal killer]

Epic Battery Thread :rating10:

 

[huskur]

Epic Battery Thread :rating10:

This should be a "sticky" right? This is the best thread on batteries to date. Hats off to the parties involved!!

 

[altjx]

Epic Battery Thread :rating10:

^ this

 

[FoxKat]

Your further clarification is spot on with trying to preserve the integrity of the Lithium Ion salt. No doubt in my mind what so ever. And I agree with you 100% that should be a consideration. But the Lithium-Ion batteries currently being used in cell phones are under "high pressure" chemically compared to commercial grade which are generally under "low pressure". That is why you also have to take into account the physical properties of the graphite, its natural expansion when placed under an electrical current and it resultant contraction when that current is removed. It's like taking a piece of paper and repeatedly folding it. It will tear. It isn't a matter of if, it is simply a matter of when. So I always tailor my advice to the item that is basically the most critical path to failure. In this case, the high pressure batteries we use make the graphite protection the priority in my opinion.

The good news is, I think between the two of us we covered just about every aspect of Lithium-Ion batteries. Which means the readers now have enough knowledge, without spending days reading very very very (LOL) dry material, to make an informed choice on how they want to use their battery and extend its usefulness.

On a side note, if they ever get silicon* to work instead of graphite/carbon, both of our opinions get thrown right out the window! ROTFL.


*Currently silicon is expanding at up to 400% of its at rest size. While the silicon doesn't crack like graphite, the Lithium the silicon is supporting does still crack. But I believe they are very close to making a break thru on all the issues. Which means we will have batteries that will go from 500 deep cycle charges to well over 5000 deep cycle charges. Basically, a game changer for consumers.

I agree with you that this debate has been stimulating and I am sure also fun to watch from others' points of view. I was wondering if I'd ever see a post after yours and before mine or vice versa from another member, for fear they would be cast out! LOL! (of course we wouldn't cast you out...we'd throw a lasso around you and reel you in!) :biggrin:

So to touch on a few things things here...

Depth of Discharge is a relative term. What that means is that it is related to what level of charge you start at. For instance, on the chart referenced above, (Fig. 2), you'll see two lines, a solid red line and a dotted black line. The red line represents the number of charge cycles at the specific percentage of original rated capacity you can achieve and at a specific charge rate. The dotted black line represents the capacity of the battery. What is interesting to note here and helps to explain all the technical mumbo jumbo Skull One and I have been spewing back and forth at each other is that these two lines run inside a grid, and the grid shows three important pieces of information related to the lines, and that they are all related...change one, the other two will change.

The left side shows the number of 100% charge cycles to expect at a given charge level. The bottom side shows the peak voltage the battery is raised to during the charging process, and the right side...here's where it gets interesting...shows the percentage of the battery's rated capacity from when it leaves the factory. Now I know some of you are saying, but wait! How can you have a percentage that is higher than 100%? This is the key to the whole chart.

Take note where the red line crosses the horizontal grid line while it also crosses the vertical grid line at 4.2V. It's 500, right (500 cycles on the left, 4.2v on the bottom)? OK, so remember from the earlier chart I used to show the number of charge cycles you could expect if discharging and then recharging to various levels from 100% downward (i.e. DoD of 25% = 75% remaining). So, in that chart a 100% DoD resulted in 500 cycles. There's the red line crossing 500 cycles, but where is it crossing 500 cycles...at 4.2 Volts. So it's saying that if you charge to 4.2 volts, you'll get what the manufacturer is representing as 100% of rated capacity at 500 charge/discharge cycles before the battery is essentially unable to hold sufficient charge to be considered "usable". That level is 80% of rated capacity in some circles of discussion but in the chart I used, it was 70%.

So if the battery can only hold 70% of its original rated capacity, and it used to be able to run your phone for let's say, 10 hours before needing a charge when it was new, then you would now need to charge it at 7 hours in rather than 10. It's still taking a 100% charge, but it's 100% of what it's able to hold. A bit of a tough concept, but just the same, it will be "full" at 4.2Volts, and will no longer last 10 hours, but now only 7 hours. So really, 100% charge should be "Full" instead, since 100% is confusing if not taken in context.

Now, since we see that 100% is a relative term, relative to what it is able to hold at any time in its life, then the DoD amount will also change as the battery gets older, even if discharging the same percentage. To use the former example a DoD of 25% would still leave 75%, but it's 25% and 75% of 100% which is only 70% of what 100% was when it was new...got it!? :blink:

OK, so now let's try an exercise. THIS is where all my teaching may start to make sense. Let's look at the Fig. 2 chart again. Notice that the vertical line for 4.2 Volts runs from bottom to top and not only does it cross through the red curved line, but it also crosses through the dotted black line...Hmmm. So what's that telling us? Well, if you look at where the 4.2V line hits the black dotted line, and then look at the horizontal line that intersects there as well, if you follow that horizontal line across to the right...WELL! It hits the 100% mark! So cool! :icon_ lala: So to look at the whole chart now, you can see that if you charge to 100% when new, you'll hit 4.2Volts, and the battery should last 500 charge cycles if the cycles are 100% charge/discharge cycles. It all makes sense. Now, look at the 120% line on the right. That line is an indication that the battery can actually supply 120% of it's original factory rated capacity (meaning MORE TIME RUNNING), but that in order to do that, you have to OVERCHARGE the battery. Here's how to read that.

See where the 120% line hits the black dotted capacity line? OK, now look at the vertical Voltage line that crosses at the same point, and read the voltage below. It's 4.4V...but it's also in what is labeled as a "Unsafe Region". So what that is saying is you could get 120% of rated capacity from the battery but you'll be putting the battery at unsafe voltage levels, and that could spell terrible trouble, such as a thermal runaway and a violent eruption of volatile gasses, heat, flames, just a bad day.

You will also notice that the 4.4V line crosses through the red curve at the bottom, and if you follow to the left at about the same level on the bottom as where that 4.4V vertical line hits the red line, you'll see the battery may be able to take that type of overcharge for about maybe 75 charges or so and then the battery has reached the 70% of original capacity level, or in other words, you've just rapidly aged the battery by perhaps as much as a year and a half but have done so in maybe only several months. Time to replace the battery (that is if it hasn't already blown up in your hand).

There is a safe overcharge range, that's upto about 4.3 V, and which will yield about 115% of original rated capacity (so in the example above, the phone would run for 11.5 hours instead of the targeted 10), but the battery would reach end of life at about 200 charges, not a good lifespan for a battery that's not removable. So where does the manufacturer put us in order to assure the battery gives us about 2 years of use? Well, it's at the 4.2V or even lower, to yield about 500 cycles or more.

Now, LAST POINT, and I'm off my soap box...and Skull One, this is for you (but the rest can enjoy as well).

Look at the black dotted capacity line and notice where it hits what voltage line at its lowest point. It hits the 4.0 V line before it drops off the chart. It really continues but there was really no reason to continue the chart and you'll see why in a minute. So if you charge to 4.0V (stopping charge before you reach 100% of rated capacity), follow the line over to the right to see the expected capacity as a percentage of rated capacity...wait, it's coming...70%~!~ So, you're telling me, if I only charge in STAGE 1 to 70% of original rated capacity, and stop charge at 4V, well below the targeted 4.2V, I'll get...what? Well, look at the red curved line at the 4V gridline...WHOA!! 2,000 cycles!

Folks, it's simple. In that case, I could charge to 70%, use to ANY percentage, upto and including 100% of that amount of charge, and I'll get no less than 2,000 cycles! Rememember, I'm NOT charging to 100% of rated capacity, I'm charging to 70% of rated capacity, but it's letting me do that 2,000 times. So I am avoiding charging to 100%, and I'm using the middle range of the rated charge capacity, and I'm getting nearly 3 times the number of hours out of the battery during its lifetime than I would if I charged to 100% each time.

This seems this proves (at least to me) that operating in the top range of the charge cycle as a method of battery preservation will acutally result in an increase in the rate of battery degradation. Now the fact is, it's also taking less and less with each charge, so I'm not getting 7 hours out of a charge by the time I get to the 2000th cycle. At that point I'd be getting 7 hours - 30% (battery being at 70% of original rated capacity), or 4.9 hours per charge, but for purposes of simplicity, we'll use the same number of hours linearly across the entire calculation. Let's do the math.

70% times 2,000 = 140,000%
140,000% divided by 100% = 1,400

SO!!! If I charge to 70%, use to 0% and charge again to 70%, I will get only 7 hours of use each time, but I'll get to do that 2,000 times, or 14,000 hours. If I charge to 100% however, and use to 0% I can get 10 hours of use, but can only do that 500 times, which gives me 5,000 hours of use. And back to the earlier 115% charge at 4.3V, that will yield maybe 200 cycles, but it will last 11.5 hours, that equates to 2,300 hours of use before the battery goes to the trash dump.

There is no disputing the facts. This is plain and simple showing you that the higher the voltage you charge the battery to, the shorter it will live for, but the more you'll get out of it each charge, and yet, the less overall hours of use you'll get as well.

I repeat my claim. Don't charge to 100% if you don't need to. Partial charges are better for the battery than full charges. Don't keep it in the upper charge ranges (85% to 100%) if possible, better to keep it in the middle ranges (maybe 25% to 85%). Don't let the phone completely discharge, plug in as soon after it reaches 15% as possible. If the phone dies on its own at 0%, make sure to plug it in immediately afterwards and charge once fully to 100% to reset the charge flag.

I'm tired now. :yawn: I'm going home! :noworktomorrow:

See you all later (later tonight, that is...I'll be back on when I'm home in a half hour!)

 

[Skull One]

As I said before, I am not disputing you are preserving the Lithium Ion salt compound. My concern is the number of time the battery is placed on the charger. Whether it be for 10 minutes or 70 minutes you are still going thru one cycle of full expansion and contracting of the graphite. So instead of only having 500 to say 750 times of this, you are talking about doing it 2000 times or more in the same time frame. So you are adding more chances for the graphite to crack. Which has the possible consequence of not being able to charge the battery ever again. But on the other hand, if you slow the contraction cycle by going thru the stage 2 charging sequence the graphite has less stress placed upon it.

BTW, partial cracking of the graphite would cause the battery to charge more slowly which is another possibility with so many charges. Something else to consider.

To summarize; I am not debating your methodology to protect the chemicals involved. I am debating whether or not the battery will be useable if the graphite is strained too much from the stress of Stage 1 only charging 2000+ times. To be blunt, I don't think your methodology is worth the risk when the device is only going to be used for roughly two years and 750 times covers that two years.

BTW; from an Android perspective, this is technically less of an issue because the battery can be swapped out without affecting the warranty of the device. But since I play in both the Android and iOS world, I have to take into account that changing out the battery in an iPhone can possible cause warranty and support issues if the end users is not careful.

 

[ufcfan72]

My battery just discharged 10% reading this thread! :beer:

Sent from my SCH-I500 using Tapatalk 2

 

[Natey2]

Lithium Ion technology will become obsolete (and so will the phone) by the time we arrive at any consensus on how we should charge. Lol.

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