I have the the 2nd Gen ASTRO E7 model A1210 26800 mha. Will the airline let me have this as a carry on?
Airline friendly
Yes.
Don’t look at the 26800mah, look at the Wh you see its a little under 100Wh.
FAA and CAA both have a convention of 100Wh max carry-on Lithium batteries
https://www.caa.co.uk/Passengers/Before-you-fly/Baggage/Items-that-are-allowed-in-baggage/
Also important, the label showing its within 100Wh
must be legible
. If its worn off then you risk them playing safe and not letting you bring it.
I own the successor Powercore 26800
If label is worn then consider downloading specs and print and keep to attempt to convince the security agent. I cannot find online the Wh or the manual so if you have the one in the shipping box then take that original/copy.