[Moto G Q&A, Help & Troubleshooting] Citizen Android:
Fast charging causes reduction of long-term battery capacity

My response here to the above answer is what I understand as a layperson who has recently done internet research into this issue of which power adapters would be ok to use with the Moto G. I will be happy to stand corrected by anyone who has contradictory authoritative information. :)

My understanding is based on the

Battery University

website entries on lithium ion batteries:

batteryuniversity.com/learn/article/charging_lithium_ion_batteries

batteryuniversity.com/learn/article/ultra_fast_chargers

Although the above quoted answer on using the Galaxy S4 charger with the Moto G is mainly correct (in that no direct damage to the phone circuitry or immediate damage to the battery will occur by using the higher amperage charger), there still will be a long-term negative affect on battery capacity by using a higher amperage charger.

I believe the S4 comes with a 2A charger. According to Motorola online support website

( motorola-global-portal.custhelp.com/app/answers/prod_answer_detail/a_id/97318/p/30,6720,9050/action/auth )

the Moto G will automatically restrict charging above 1500mA. So that would mean that a 2A charger would cause the Moto G to charge at the 1500mA rate. No damage would be done to the phone circuitry charging at the allowable rate of 1500mA, but the question remains if there would be a long-term reduction of battery capacity by charging at 1500mA for a year or more. The official Motorola charger sold online is now 1200mA. So the comparison should be between charging at 1200mA versus 1500mA.

According to the Battery University website, the optimal range to charge lithium ion batteries is between .5C and .7C. Lower charging rates result in less reduction over time of battery capacity. The C-rate unit is used to measure charging and discharging rates. A value of 1C is equal to the rated amperage of the battery. So, for the Moto G, 1C is equal to 2070mA. Therefore, according to this recommendation, the optimal charging range for the Moto G would be between .5 x 2070 = 1035mA and .7 x 2070 = 1449mA. So, charging at the Moto G's maximum of 1500mA would be just barely outside the optimal range.

But extrapolation from Figure 1 in the Battery University 'Fast and Ultra-Fast Chargers' article indicates that there would be an additional 9% reduction of battery capacity by charging at a 300mA higher rate of 1500mA over the official charger rate of 1200mA. This additional reduction in capacity of 9% would be over 500 charging cycles, or about 1.5 years of average usage. The normal reduction in capacity just from aging over 500 cycles is already listed as 16%, so adding the 9% would bring it to a total of 25% loss of battery capacity after about 1.5 years.

--------------------------------------------------

UPDATE and CORRECTION:

I have more authoritative information directly from Battery University that changes the conclusion I draw above based on my effort to extrapolate from the Battery University website article.

The extrapolation I did above was based on the additional loss of battery capacity cited when going from a 1C to 2C charging rate. But according to direct communication from Battery University, when charging at a rate below .7C there should be no measurable improvement to capacity by using slower charging rates. Charging above .7C would still be expected to add more stress to Lithium Ion Polymer batteries and likely add to long-term reduction of capacity.

So, what this means for the Moto G and Nexus 5 is that there should be no measurable difference between charging with 2A, 1.2A, 1A, or 850mA chargers as far as effect on long-term battery capacity goes. Both the Moto G and Nexus 5 are supposed to automatically restrict the charge rate at 1500mA even when using a faster charger, which is just at or below .7C for both phones. So, as long as the charger dependably keeps to 5V, a higher amperage 2A charger will be faster but pose no problem to long-term capacity.