A10,000 mah power bank can charge most smartphones at least once, and can also charge small devices like the iPhone 12 mini three times. How Many Times Can a 10,000 Mah Power Bank Charge an Iphone 12. The 10,000mAh power bank can charge an iPhone 12 3 times. The 10,000mAh power bank can charge a Samsung S20 over Apower bank typically has a capacity of around 5,000mAh. So, in order to determine how much power you’ll need, you can divide that by how many time you charge a day. However, we don’t know the capacity of smartphone battery and other devices. So we recommend to use 5000mAh for most of smartphone and tablets. Forexample, let's say you have a 5000 mAh power bank that you want to charge in 2 hours. How much current does your charger need to output to charge it at that rate? 5000 mAh ÷ 2 hrs ÷ 1000 = 2.5 A. It turns out you'd need to buy a charger capable of outputting 2.5 amps in order to charge your power bank that quickly. Numberof times you can charge your device Compare the power banks BlueBuilt Power Bank 20,000mAh Charge your A4000 mAh battery can last up to 8 hours on a single charge. This means that you can use your device for a full day without having to worry about recharging it. Rate this post. In general, a 4000mAh battery will last for about two days with normal use. However, this can vary depending on factors such as screen brightness, app usage, and Ipurchased this power bank charging unit the day before I left on a 4 day camping trip and it really came in handy! It is a true lifesaver. It holds true to its 4000 mAh capacity rating, and I was able to fully recharge my phones 2800 mAh battery and get to about 40% charge with the remaining power the second time around. A4000 mah power bank is a great option for charging smartphones. It is able to charge most smartphones completely with enough juice to spare. So, there you have it! It only takes 20 minutes to charge a 4,000 mAh battery with a 125-watt charger. That’s pretty impressive, and it’s certainly a lot faster than charging with a standard 25 BatteryCharge Time Calculator Enter Information. Battery Capacity (mAh) Charge Rate Current (mA) Formula Time = Battery Capacity Charge Rate Current. online calculators for multiple niches including mathematical, financial, Health, informative, Chemistry, physics, statistics, and conversions. IctluMu.