I've seen you make this claim numerous times. Do you have any evidence to back it up, because my own monitoring shows proper charge patterns are used. Running above the voltage the battery is designed for can also cause an explosion risk.
Well you're happy to believe whatever you want. I have external "smart" chargers that interface to my PC over USB for logging, along with a recording analyzer (that does likewise) and a couple of probe wires into the battery pocket with the back off make it pretty easy to monitor on a removable battery device.
Second, since I also have said properly-programmed smart charger, I know how long it takes to run a charge using a charger that properly switches to saturation and runs the correct profile. Simply put you can't run a proper charge on a Li chemistry battery from ~10% to 100% in less than about 3 hours without cheating. Proof that these batteries do NOT require a higher charge voltage comes in the form of them reading 100% when charged outboard on a proper Li chemistry charger and then inserting them into the phone and they do indeed read 100%. In addition my recording charger knows how many maH went in as it integrates and reports that over time; combined with my analyzer which can run a controlled discharge test (that I've also done) I've verified that indeed a 3200mah "labeled" battery that Accubattery says has a 3200mah estimated capacity, when discharged at 0.2C, indeed really does deliver 3200mah within a few percent. Thus I
know that when charged properly by said external charger I really do store the full capacity of cell into it.
I will add a couple qualifiers to my opinion, though. Current Li-ion technologies have resulted in "high voltage" batteries capable of 3.85V nominal (4.4V peak). Phones with these batteries, like the V20, can and do run up to 4.4V during charging. Also, 100% on the meter doesn't always equate to a fully charged battery. I've noticed the charge current lasting quite a while after the meter shows 100% before fully tapering off. One could speculate this is to get people to unplug before putting too much stress on the battery.
CAPABLE of accepting that voltage without metal-plating and catching on fire is not the same thing as treating the cell properly, and getting the designed cycle life out of it. The "newer chemistry" cells can indeed accept charge without turning into torches at a tenth of a volt or so higher charge voltages BUT they still take damage when you run them at said voltage.
Here's a snapshot of "Accubattery" on my V20 with it at 80%. There is no way that cell is being charged "constant voltage" at 4.386V and ~1,400 ma. Further, there is no way that a proper saturation charge profile from 80-100% would require only 18 minutes to complete. Note that this is a QC3.0 charger and its "average" charge rate during that cycle was just over 2,000mah or just over 63%/hour. It is
not possible to run a proper charge profile on a Li chemistry battery and obtain a sub-2-hour complete charge.
CONSTANT VOLTAGE MEANS CONSTANT VOLTAGE and yet the charge profile on these cells in EVERY phone I've instrumented, whether by app or physical probes on the battery, over the last five years continues to allow the voltage on the cell to RISE beyond its saturation voltage. I've yet to see
ONE phone that performs an actual bulk/saturation charge -- that is, charge at up to 1C (if you have the current available) until the saturation voltage is reached and then
hold the output voltage CONSTANT and allow the charge current to taper. Instead
every phone I've seen over the last many years never actually performs a saturation charge at all; they intentionally overdrive charging from the saturation point all the way until full. What's even worse is that all these charging circuits will then "float" the battery at an effective 100% charge which materially compounds the damage; if you leave the phone plugged in overnight you're hosing your cycle life
twice.
THAT'S WRONG; what SHOULD be done by the charge controller is that when the saturation change-over voltage is reached the voltage should be held CONSTANT (no rise
whatsoever) and the current allowed to taper. The logical reason they don't do it that way is TIME. When the saturation charge completes the battery should also
not be held on a float charge at all. The correct solution to this is for the charge controller to be able to run the phone as a power supply and to electrically disconnect the battery when the charge is complete so long as it remains plugged in to a power source that can deliver sufficient current. The reason
that isn't done is that modern phones can demand upwards of 2A on a burst basis and yet the standard USB port on a computer can only deliver 500ma and there is no way to *know* what the maximum current delivery capability is even on a QC charger (QC negotiation doesn't tell you that, just voltage), so you'd get unsolicited undervolt resets if that was done.
The reason I recommend using something like Accubattery and disconnecting at 80% is that while this doesn't eliminate charging overdrive entirely it materially reduces the exposure of the cell to it and, if you additionally don't charge overnight at all you will dramatically improve cycle life. It costs you 20% of your runtime before you need to recharge to do that but until phone manufacturers start allowing customers to choose either their "charge me fast" current setting (at the cost of half or more of the design cycle life of the cells) or a "charge me CORRECTLY" setting it's the only reasonable defensive measure you can take.
If you're wondering what the results look like I've had my V20 now for a number of months and, with the exception of when I'm on road trips and using it for nav (where the abuse of float charging is less than the abuse of continually cycling it during the day, never mind that when screen-on the V20 will not charge at faster than ~500ma so when the screen is locked on for nav the abuse the cell takes is materially lower) this is how I've charged it. You'll note that Accubattery thinks the cell -- the same one I've had in the phone since I got it -- has 102% of it's OEM rated capacity. You can also note the estimated SOT -- approximately 5-1/2 hours and two full days of standby time.
You do what you want -- I will do what I know, from instrumenting various phones charging circuits and what I know of Li chemistry batteries,
works to materially prolong battery life. With a V20 where you can trivially swap batteries this matters less than on a phone with a
sealed in the case battery -- on those devices it becomes even more important not to abuse the cell for obvious reasons.
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