The standard charger that comes with the 5.7 is rated at 10 amps (into the battery). An optional 15A charger is available for faster charging.
The battery charging port looks like a standard 3-pin XLR audio connector but it's keyed slightly differently. Pin 1 is positive, pin 2 is negative, and pin 3 (center) is not connected.
The first time I charged the battery, it had drained down to the last green LED (then there are 2 orange LEDs and a red one) on the integral State of Charge indicator. I use a very inexpensive (about $16) Chinese power meter (part number PZEM-061) to measure AC power consumption. This indicated the charger drew about 550 watts from the AC line at startup. An hour later it was around 600W. Two hours later it was down to 100W. It took less than 2.25 hours to completely charge the battery. During that time, the charger consumed 1131 watt-hours from the AC power line. Our electric rate varies by season but is currently about 17 cents per kWh. So, around 19 cents to charge a mostly-depleted battery.
For the second charge, the battery was completely depleted. It took 2 hours and 24 minutes and drew 1.240 kWh from the AC line (20 cents worth of electricity). There's a fan on the charger that runs while the battery is being charged. It's easy to tell when charging is done as the noise from the fan ceases. The battery measured 53.8 volts (unloaded) at the end of the charging process.
The third charge (after at least 0.8 hours of riding) took under 1 hour and drew 527 Wh from the AC line. I then “topped up” the battery after 4 days of letting it sit idle. That only required about 13 Wh from the AC line. For this experiment, I also measured the DC power going into the battery. This test indicated the charger itself had an efficiency of about 72 percent. I expect that, when doing a full charge, this number will improve somewhat.
For another charge, I measured the DC power going into the battery at 559 Wh. The AC side consumption was 640 Wh. In this case, the charger was 87% efficient (which was better than I had expected).
One note regarding the 5.7 charging process. Unless the Anderson connector is unplugged, charging will also power up the motor controller. Although the power consumed may be small, it is completely wasted. This is not the case with the ePure, however.