It would be cool if they had an add on battery that fit seamlessly. Or imagine a swappable battery? And then ensure you only use the 100wh when flying?

The airline rules are a bit arbitrary. They have allowances for mobility devices but don't seem to take any extra precautions for them when they have bigger batteries. There are still a lot of dangerous gaps in airline safety when it comes to lithium batteries.

> The airline rules are a bit arbitrary. They have allowances for mobility devices but don't seem to take any extra precautions for them when they have bigger batteries. There are still a lot of dangerous gaps in airline safety when it comes to lithium batteries.

They're absolutely arbitrary. From what I've seen, one of the major problems is wild variation in quality. An 80Wh battery from six-random-letters-off-Amazon is going to be more dangerous than a 160Wh battery from a reputable manufacturer.

> An 80Wh battery from six-random-letters-off-Amazon is going to be more dangerous than a 160Wh battery from a reputable manufacturer.

I think the point is more the amount of energy stored in a fully-charged or 80% charged battery.

In that respect it doesn't matter if your 160Wh battery is from a leading manufacturer or some knock-off factory. 160Wh is 160Wh.

Also the airlines have to draw a line about what level can be permitted without specific permission, what level needs authorisation and what level needs dangerous goods handling.

So suspect the numbers feel arbitrary because its the result of various committees having consulted with various different interested parties and then having the unattractive job of needing to write some rules at the end of it.

It is an inevitable part of the process that some numbers will need to be picked which can easily be explained to passengers, and are workable for manufacturers and the airline industry.

Yup. For example they don’t care if you bring two laptops each with a 100Wh battery.

You can take along a battery pack with usb-c and charge the macbook.

> You can take along a battery pack with usb-c and charge the macbook.

Actually not quite. The rules have tightened up significantly on powerbanks.[1]

First the same size rules apply as always, i.e. 100Wh, 100–160Wh with personal individual passenger permission and never above 160Wh.

Second, max two per passenger.

Third, you are prohibited from:

     - using them to charge devices on-board
     - recharging the power bank itself on-board.
[1] https://www.caa.co.uk/commercial-industry/airlines/dangerous...