Li-On Power bank

[Kiltrash]

Hello and may I quiz the cabin as to the suitability of a Mobile Phone Power Bank marked as 20000 Mah.
Using the formula stated on the BA website this equates to 100Wh which is the max allowed.
It can ONLY be carried in the cabin in a protective packaging, Not Hold Luggage
You are allowed 2 of them max
If the power is NOT marked it cannot fly
It needs to be declared at Check In

Questions are
1/ Can it be used in flight if there are no suitable charging points at seat?
2/ Assuming you have no hold luggage and check in on line and go to security Are you meant to go to the check in desk and tell then?
3/ Is it reasonable to assume all carriers have the same policy or for a multi carrier trip check each?

My next trip is 3 week jolly to OZ and flying Thai, Virgin Australia, Jetstar and Etihad

Thoughts and experiences Please

Many thanks for your time

[dastocks]

I have a power bank that claims 300000 Mah capacity - it's good for fully charging a mobile and/or tablet a couple of times with juice to spare, This does not have the capacity marked and it sat in my carry-on laptop/personal bag on weekly trips to Europe (mainly on BA) for over 3 years with no bother.

1/ yes
2/ I never bothered. The (installed) laptop battery I was also carrying was probably at least as great a risk.
3/ YMMV, but be aware you will have to keep it with you if a bag gets pulled at the gate to go in the hold.