Will my Droid Maxx charge any faster with a 2.1amp port vs. a 1 amp port, using a 'charging only cable'.
Some chargers are better than others. Few months ago I tried various chargers, devices and cords. Largest draw I could create was .94amp. Many 2.1amp chargers are designed for Apple devices.
Charging rate is limited by the phone itself, so as to not charge the battery faster than specified. Charging faster than specified will shorten the battery's lifespan (how long - or how many times it is able to be recharged for, versus runtime, how long it will run on a full charge), so connecting a 2.1Ah charger will charge the phone no faster than a 1Ah charger will. However, charging with a 750mAh charger WILL charge SLOWER than a 1Ah charger, or anything above.
Since the battery is not user-serviceable/replaceable, the lifespan is critical to the phone. Manufacturers will target a balance - number of charges versus speed of charging, to make sure the batteries last for the expected "serviceable life of the device" which is between 1.5 and 2 years, or at around 500 full charge cycles which is 100% charge and use of that 100% charge, so a charge to 100%, use to 50% and charge to 100%, followed again by use to 50% is considered one full charge cycle (50% * 2 = 100%).
A battery of the type in our phones is considered beyond its "useful life" at the point where it will no longer take a charge in mAh, that exceeds 80% of what it was originally spec'd for. So in the case of the MAXX, 3,500mAh is the "rated" capacity, so when (not if, but when), the battery reaches the point where it will only hold 2,800mAh, it is considered beyond "useful life". That means that if it was able to last 48 hours on 3,500mAh, it should then only last 38.4 hours at the point where the battery is considered end of life. Does that mean the battery is dead? Well, of course not, but it does mean you may be hitting the charger more often per week than when you first bought it.
Another thing about these batteries...they actually PREFER to be partially charged more frequently, so for instance, if I've used it to 35%, instead of continuing to use to 15% or 10%, instead I'll plug it in for maybe 1.5 - 2 hours and boost the charge level up to near 80% or so. If you use and charge these batteries in the middle 60-70% of total capacity, you will extend the life dramatically, perhaps as much as 1,500 to 2,000 charges before it reaches that end of "useful life". So that being said, if you charge to 100%, and/or use to 0%, you are actually shortening the lifespan of the battery, since it's stressful to the battery to remain in either the top 20% (80%-100%), or the bottom 20% (20% to 0%). If you want to get the absolute longest lifespan of the battery, charge to 80% and use to 20%, and never go outside those ranges (except during meter trainings, about once every 2 months).
"Saving DROID Razr's, one battery at a time. :-)" - (credit SallyC)
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