I've noticed that my battery meters are doing some strange things and could use some calibration.
I'll answer them in order...
1. On the draining from 100% to 10% step, does it matter if you turn the device off in during this. I prefer to turn my devices off at night, and this would be a multi-day process for me (especially on my Nexus 7, I could easily take 3 or 4 days on this step alone). Should I leave my devices on overnight during this process.
You're bringing up a good question and honestly I've not had this asked yet (strangely enough). The answer is no. Whether drained under a constant on state or drained over several on periods separated by either rests or off states, the same results will be obtained - that is at the point when the phone indicates it has reached 10% and signals it's time to charge, that flag has been successfully set.
There is some possible measurable benefit to draining slowly rather than say perhaps sitting there and watching streaming videos until it dies, in that a slow drain is a more efficient use of the battery's power, resulting in more mAh (milliamperes per hour) of power actually being provided by the battery over the drain cycle. This also will allow the voltages to drop more gradually and not result in an artificially depressed voltage due to high current draw, signaling a 10% level prematurely. So in capsulation, don't "try" to drain it, simply use it as you normally do and wait for the result to happen naturally.
2. During charging, you recommend using the wall charger with the device off. Actually this applies to charging all the time, not just calibration - but is this just for speed, or is it preferable? Is using the wall charger better than plugging the usb into the computer? Is leaving the device off while charging better than leaving it on?
I ALWAYS recommend the stock wall adapter supplied by the manufacturer to be used, and for lots of good reasons, though I have been met with arguments both for and against my opinions. Still, I have argued the "against" successfully with more than sufficient third party supporting information.
Reasons why you should always use the stock wall adapter supplied by the phone's original manufacturer.
You can be sure that the;
- voltages and amperages (current - i.e. mAh) are within strict tolerances and suitably matched to the battery to safely charge the battery
- charge rate is within the expected ranges to provide the specified life expectancy of the battery
- battery will last for the expected life of the device
- battery will not be unduly stressed risking potential permanent damage to the battery or the device due to overheating, expansion, explosion or fire
- warranty for the device will not come into question due to a non-authorized charger being blamed for a failure (which would in fact void the warranty)
- charger has clean power where voltages and current are free of Radio Frequency (RF) interference, line voltage fluctuations, and remaining 60 hertz ripple
- charger has high quality components which will last longer than comparable high-profit "knock-off" or "Universal" chargers manufactured for very low sale price (primarily manufactured in China)
- charger has all the necessary safety features implemented and meets all required safety regulations to protect life and limb
- charger will provide the least power waveform interference to the device's functionality and either minimize or eliminate "ghost typing" or other erratic touch-sensitive screen responses
Reasons why you can safely use the USB out ports on almost all computers (most specifically those manufactured in the last decade), but why they will provide varying degree of reliability and charge rate.
You can be relatively sure that the;
- computer USB ports have met "standards" regarding power quality, voltage, current output and pinout configuration
- current is highly unlikely to exceed the maximum current demands of the device
- current is potentially LESS than would be required to charge the device while it is using power at a high rate such as while watching streaming video, resulting in actually discharging (though at a slower rate) while connected to charge (specifically in USB 1.1 or USB 2.0)
- device will charge if either powered off or in a low-power "rest" state but that it can take from somewhat to considerably longer to charge than with the stock wall adapter (depending on whether it's USB 1.1, 2.0, or the newest high-power 3.0)
Leaving the device OFF while charging is the most reliable way to assure a full charge of the battery, while reducing or eliminating stress on the battery during charge. It is also the safest way to charge, and will charge the fastest of all methods. Still, it is not required that you power such devices off while charging under normal operation. These devices are designed to provide nearly 100% functionality while connected to a charge adapter. Typically only the highest demand functions or heavy multi-tasking will consume more power than the charger, causing the phone to either not appear to charge at all or even to lose power over time while connected due to the rate of power consumption being higher than the rated output as supplied by the charge adapter.
Turning the device OFF while charging is most useful in two situations. 1) You need the most power available for the longest run-time you can get out of the battery due to either expectation of an intensive use or need for long standby operation, and you will be out of range of any reliable power source for the entire expected time. 2) You are performing a "Meter Training", and in this situation it is critical that the power be turned OFF to assure that there is no "parasitic load" of the device to cause misreading and miscalculation of the battery's State of Charge (SOC) during charging.
Other than the two above examples, in most cases you can charge at will with power on, whether for a full charge or partial charge and with no perceivable ill effects. In fact, it's a little-known fact that these batteries actually prefer to be partially charged multiple times rather than be fully charged each time as it causes less stress to the internal structure of the battery and results in a longer lasting (greater lifespan), battery over time.
One final opinion (do with it as you will)...
Stay away from third party chargers (no-name, universal, RAPID or otherwise labeled) if at all possible, as these are the least well engineered and the most likely to have either inherent problems with power quality or safety features, or suffer early failure, and can potentially cause irreparable harm to the device and/or battery, as well as the potential to result in personal injury. Also, take care not to use charge adapters manufactured by a well-known company but for another phone or device manufacturer, since although they may be well-engineered themselves, they may also be designed to dispense higher current rates than those recommended by your device manufacturer. In other words for instance, don't use a charger for an iPad to charge your Droid RAZR. By charging with these "other" chargers you may actually be doing long-term harm to the device or battery by reducing the expected lifespan of the battery or by overheating components and causing electronic and other failures. A battery that is charged too quickly can heat up, expand or "swell" and put pressure on components, cause cracking of the circuit board, separation of electrical connections, tear contacts from their solder, and even crack the display screen from behind. You have been warned.
I hope this information is helpful to you and others and that it contributes to a greater user experience for everyone.
