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.
Actually I believe this will be more and more of an issue as time goes on, at least in the near future couple years, because manufacturers are moving away from user-replaceable batteries and toward the LIPO batteries which are far easier to damage, and so are being installed as semi-permanent installations. Case in point, the LIPO in the RAZR/RAZR MAXX are connected by a mylar ribbon connection and have Torx screws locking the connection to the motherboard. The ribbon is delicate and can easily be torn, making the battery completely useless. Also most consumers don't own or can't readily get their hands on the required T5 driver to make the change.
Furthermore, as the trend toward thinner and thinner phones continues, techniques to strengthen the physical phone and minimize damage from flexing has moved the build style into a "laminate" structure, where each layer is fused to the next in a multi-layer sandwich configuration with adhesive double-sided tape. This makes the removal of the old battery and replacement of the new that much more tedious and potentially problematic.
Now going back to something else you said just above;
"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."
Question, how did we get to 750 charge cycles? It has been noted many times that the battery is expected to be charged approximately 500 times (based on 100% of rated capacity charges - i.e. to 4.2V as an assumption). If that is so, then the battery will reach "end of life" only in 1 1/4 to 1 1/2 years (too early). That doesn't sound like what I would consider a reasonable projection since the phone is targeted for a 2 year lifespan (using the "New every two" marketing plan as a frame of reference).
I would dare say that the manufacturer figures you are going to use it off the charger at between 90% and 100% SOC (depending on how soon since the last Stage 2 charge ended), and will hopefully place it back on charge no later than about 15% SOC, so in other words, using between 75% and 85% of the total rated (or age-based) capacity. Furthermore, they state even in their own user manual that to extend the battery's lifespan shorter charges more frequently will add life.
Take my usage pattern for example. I drive to work 1/2 hour and drive home 1/2 hour. In each trip, I am charging in Stage 1 at C.43, so I typically replenish the charge about 25-30% of the total capacity, but that happens at two different points in the discharge cycle. First, it happens on the way in when the phone is often only off the charger for an hour or so, so the SOC at start of the drive is about 80-90%. By the time I am at work, its back to 100%. Then on the drive home, I am plugging into the Dock at about 40% SOC, so by the time I get home, I'm back to about 70%.
In the last 7 24 hour periods, my usage has been (usage/lowest level) 50%/40%, 120%/40%, 155%/15%, 150%/10%, 90%/40%, 0%/80%, and 50%/60%, for an average of 87.8% use per 24 hours. In all those 24 hour periods, I am using the phone in the range of between 10% and 100%, and clearly the bulk of use was from 20 to 60% DoD (depending on at what point I pulled it off charge). So I am generally using the phone in the upper middle ranges, but only using at most 60% before charging again, meaning I'm charging from 10% to 60% with each plug in. I should expect probably 750 100% charges over my battery's life, so I will likely see the battery continue to perform within acceptable run-times between charges though I will also have to charge more frequently as the battery ages. This all seems to fit quite well with average use projections likely made by the manufacturer.
I have another question for you, Skull One. If your intent was to suggest people will gain the longest battery life if they use the phone only for the first 15% to 40% of capacity - in the top of the range from 100% to 60% as you indicate in this original quote;
"
You want to charge from 60% to 100% so you spend LESS TIME in Stage 1 charging and do less damage to the battery. The sweet spot is actually 85% to 100%."
Won't that result in MORE charges over the same typical time frame or life of the product (i.e. 2 years), and if so, won't that actually do MORE damage to the Graphite Anode as you suggest above? If so, then your suggested method to extend the battery's lifespan is then negated (based on your concern for the Graphite Anode), by the increased number of charging processes intended to extend the life. In other words, one cancels the other out, and the net result may actually be a shorter life, not a longer one.
You actually point to 85% to 100% as the sweet spot, and you had also mentioned in an earlier post (prior to your editing it out) something to the effect of using for "the first 10% to 15% and charging", versus from unless I am misinterpreting your information either in this comment or in the commentary of the post quoted at the top, because they seem to contradict each other. This would also dramatically increase the number of charging cycles, so we're back to the issue of the Graphite Anode being stressed due to expansion and contraction as you suggest.
Also the chart referenced in my previous post (Fig. 2) clearly shows that the upper range of the charge (i.e. the higher voltage the battery is charged to), is more detrimental to the lifespan (number of cycles), but will also yield more run-time per charge. This again seems to contradict your earlier recommendation of charging and operating in the upper range of SOC, 85% to 100% (or high end of voltages, i.e. 4.1V-4.2V versus 3.9V-4.0V).
What I am saying is I REALLY want to believe you, and to be able to feel in my mind and heart that I have misinterpreted the data. I am more than happy to admit when I am wrong. However I am not feeling this. Everything I read, technical, chemical, scientific, marketing, instructions, all point to the same conclusion which is to NOT charge to the top range, charge shorter charge times and more frequently and (I think we both agree on this point) NOT to discharge to 0% and instead try to resist going below 15%, as recommended by the manufacturer and indicated by the "Low battery" warning.
Look, I am ALL about providing accurate and helpful information to enhance the user experience, but I'm just not feeling the love from your recommendations yet feeling it loud and clear from everything I read elsewhere. Perhaps if you could provide some references to prove your claims (as I have to prove mine), then I can read your references as I am sure you have mine and maybe we can find the common ground, for the benefit of all those who are watching this debate ensue and all those who will gain from its final determination and advice gleaned from it and passed on in the future.
In other words, help me to believe your point of view as I have tried to help you believe mine.
:hail: