Most portable power banks can handle charging a phone a few times, but charging tablets takes a bit more oomph. The Mophie Powerstation XXL delivers thanks to its 20,000 mAh battery and 18W USB-C Step 1: Get some 18650 cells. These boards will work with either 1 lithium-ion cell or several lithium-ion cells in parallel. So, if you want a super compact low-cost DIY power bank, you can make that work with just 1 cell and this board. If, however, you want a more reasonable, higher-capacity DIY power bank, then you are going to want to use 2. Anker 337 Power Bank. Anker 337power bank provides extra capacity for your iPhone, Android phone, iPad, or tablet while you’re on the go. This 26800mAh charger from Anker powers most phones or tablets 6 times, a tablet at least 2 times, and other USB devices multiple times. The more impressive part is that the Baseus Blade has a 100W Power Delivery output from either of its two USB-C ports. The charger also has two USB-A Quick Charge ports. So you can charge your Surface Pro 8 at its max speed with its power bank. The max recharging speed is 65W, so I recommend using a 65W wall charger to recharge the power bank. Goal Zero Sherpa 100AC. Best Rugged Power Bank: Goal Zero’s Sherpa 100 AC is so massive in its storage capacity, that the brand doesn’t even measure the total onboard storage in milliamps — but we did the math, and it breaks down to about 110,000 mAh, which is the equivalent of nearly 40 full iPhone 12 charges. USB-C is bidirectional.. you can charge or be charged using the same port. this is expected behavior. When the power bank reaches a lower battery % than the phone, it will change to charging the power bank. that may be "expected behavior" but it doesn't make it any less of a massive failure of design. Here’s a list of the best ones out there. Why limit yourself to just power banks. Take a look at these pow­er strips With USB‑C PD. 1. RAVPower PD Pioneer. Capacity: 20000mAh. Total Watt: 60W This is one of the fastest power banks I have. It has a capacity of 10,000mAh, which is a lot for this compact size, and it charges at full 30-watt speeds. That’s insanely fast for a power bank! This way, you will be able to maintain longer life of your power bank device. 4 ways to maintain your Power Bank. 1) Use original charger of Power Bank: Most of the time, the power bank’s performance deteriorates simply because it was being charged from a different charger than its original one. The Realme power bank features a capacity of 20000mAh and supports 18W fast charge, allowing you to charge your devices quickly. It supports two-way fast charging and comes with 12 layers of 78wG.