Read https://www.cnet.com/forums/discussions/high-capacity-battery-pack-for-dell-inspiron-5770-laptop/
Did you have to use it's AC outlets?
Good news, so far ... My new AIVANT AC Power Bank 42000mAh/200W is charging my Dell Inspiron 17" 8th Generation i7 Laptop ... up to 58% in around 50 minutes. This unit is small enough that I can carry around in a backpack, or messenger bag. The Power Bank measures: 7-3/4"x5-1/2"x1-3/4".

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