S5 Battery :
2800 mAh
3.85 V discharging voltage
4.4 V charging voltage
Assuming S6 Battery is same except for the total capacity:
2550 mAh
3.85 V discharging voltage
4.4 V charging voltage
Estimated capacities charged to different voltage thresholds:
Voltage | Capacity at cut-off voltage |
3.80 | 60% |
3.9 | 70% |
4.00 | 75% |
4.10 | 80% |
4.2 | 85% |
From extrapolation 4.4 V gives 0.88 (88%)
Capacity as a function of charge voltage on a lithium-ion battery
Since the rate of charge (current) will be constant until we hit the cut-off voltage, it would be safe to assume that below 88% of the capacity will be charged at our maximum supply current. (Charger output).
So, 88% is the cut off point. 1 A charging and 2 A charging will reach the same cut off point, so using that, we can now guestimate.
Using this, we can guestimate galaxy S6's 1 A charging time:
88%*(2550 mAh) = 2244 mAh
2244 mAh/1A = 2.244 hours
Simply divide my 2 in order to get the time for 2 A charging because the slope is constant up to the cut off point
1.122 hours extra charging time for 88% battery is estimated for this particular charger.
Please keep in mind that this is an estimation using assumed values and curves.