Ugreen Nexode 20,000mAh 130W Best power bank for large power capacities 3.1 / 5 Score Why we like it: The Ugreen Nexode 20,000mAh power bank is a powerhouse of functionality. Choose this power bank… If you want… Anker Nano 10,000mAh The best power bank overall. Here are the key factors I consider when testing power banks: Capacity : I've seen plenty of companies make exaggerated claims about their power bank's capacity. FAQs on power banks Are power banks and portable chargers safe? Another issue is that power banks can get damaged, and damaged power banks can be unpredictable.