Yes, you can charge it with a higher mAh wall charger, but this is straight from Innokin:
This product is intended for use with the charger
provided with the unit. We recommend you always use
a high quality 5V 500mA USB wall charger (CE/UL
Certified). Use of unauthorized chargers may lead to
overheating and possible burning of items in contact
with the unit. Innokin Technology is not responsible for
battery and charger explosions, fires or malfunctions
due to the use of a low-quality charger. This product
does not come included with any wall charger
Using a 500 mAh charger will generally take ~ 3 hours to fully charge the MVP (from fully depleted). Using the USB port on your PC, provides a maximum 500 mAh charge rate, but typically only provides an average of 350-400 mAh (depending on load on your PC's power supply, your PC could actually DRAIN the battery during peak-load-times), thus extending the charge-time to 4 hours, or longer. A great majority of people will charge devices which come with ONLY a USB cable strictly via PC USB port, which is why I gave the 4-6 hour estimate. Using the appropriate wall-wart charger, will shorten that time to 3-hours.
Charging via a higher mAh rated wall-wart will speed the process, but depending on the charging circuit of the MVP, it may not allow it to reach more than 70-80% charge (by stopping the charge-cycle after reaching Stage-1), thus reducing the run-time between charges (but this may increase the life-span of the battery). Furthermore, if the circuitry does not stop charging at Stage-1, or quell the charge-cycle properly to Stage-2 by reducing the current, the battery may overheat, become stress-damaged (shortening the life-span), or possibly experience catastrophic failure.
Here's some more info on Li-ion battery charging, courtesy of Cadex:
The charge rate of a typical consumer Li-ion battery is between 0.5 and 1C in Stage 1, and the charge time is about three hours. Manufacturers recommend charging the 18650 cell at 0.8C or less. Charge efficiency is 97 to 99 percent and the cell remains cool during charge. Some Li-ion packs may experience a temperature rise of about 5ºC (9ºF) when reaching full charge. This could be due to the protection circuit and/or elevated internal resistance. Full charge occurs when the battery reaches the voltage threshold and the current drops to three percent of the rated current. A battery is also considered fully charged if the current levels off and cannot go down further. Elevated self-discharge might be the cause of this condition.
Increasing the charge current does not hasten the full-charge state by much. Although the battery reaches the voltage peak quicker with a fast charge, the saturation charge will take longer accordingly. The amount of charge current applied simply alters the time required for each stage; Stage 1 will be shorter but the saturation Stage 2 will take longer. A high current charge will, however, quickly fill the battery to about 70 percent.
Li-ion does not need to be fully charged, as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge, because high voltages stresses the battery. Choosing a lower voltage threshold, or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime. Since the consumer market promotes maximum runtime, these chargers go for maximum capacity rather than extended service life.
Some lower-cost consumer chargers may use the simplified “charge-and-run” method that charges a lithium-ion battery in one hour or less without going to the Stage 2 saturation charge. “Ready” appears when the battery reaches the voltage threshold at Stage 1. Since the state-of-charge (SoC) at this point is only about 85 percent, the user may complain of short runtime, not knowing that the charger is to blame. Many warranty batteries are being replaced for this reason, and this phenomenon is especially common in the cellular industry.
