Power bank comes with different sizes and shapes. Portable power banks are the best. Small in size and best battery capacity is all everyone wishes. Light weighted power bank are easy to carry. Charge it and keep it in your bag. Second thing to consider is power output which means fast charging of your device. Efficiency must be checked, it should take less energy to get full charged. The most important thing to consider is mAh capacity.
Output offered by power banks
The output voltage of power bank should be equal or higher than your device. For example, if your device has a 2500mAh battery capacity, buy a power bank with at least 3000mAh capacity. Sometimes, to avoid further costs it is useful to spend a bit more while purchasing a power bank. Go for a good brand. If you are looking something better than a usual power bank then you can visit www.amazon.com/verdict-Verdict-Juniper-Power-Bank/dp/.
Some power banks offer good mAh capacity but with one USB port. Some power banks provide two ports so that you can charge two devices at a time. With multiple ports simultaneously charging is very easy.
Types of power banks
There are two types of power banks which are available in the market now-a-days. One is Universal Power bank which comes in different sizes and capacity and can be used to charge all the devices. It fits to your budget also. Other is Solar charged power banks which can be charged placed in sunlight to get charged. Solar charging is not so fast, it has an option to charge via cable as well.
Warranty of the power bank is also to be considered. If you have a doubt, check the instructions provided for the power bank and then choose the right power bank. Many brands claim to be the best but the above factors will definitely help you to choose the right one for you.