I recently heard that for some flights you need to turn on your phone or laptop to increase security. Especially to prove that the battery is not a bomb.

However, this got me thinking about my own laptop which actually has 2 batteries. Obviously turning it on will not prove that both batteries are real, so I wondered whether I will be allowed to bring it on the plane or whether I should expect complications?

2 Answers 2


I've taken a laptop with 'normal' battery and external battery slice through airport security multiple times and never had any problems. Although I've also never been asked to turn it on to prove it's not a bomb.

  • Rules be a changing, I'm told Commented May 28, 2015 at 15:46

Laptop batteries are usually Lithium ion batteries. FAA regulations state that you may bring up to two such batteries with a maximum of 160 Wh in your carry-on (should be similar in other regions). Your laptop batteries are very likely below that limit. Please note the carry-on part; large Lithium batteries are prohibited in checked-in baggage due to fire hazards.

Addendum: As you're actually forced to take them in carry-on, I wouldn't expect difficulties. Still, if they're not too difficult to remove from the Laptop: in case you get into troubles, you could simply remove one battery, show that the laptop works, insert the second and remove the first and demonstrate a working device again.

  • Note that the "2 batteries " limit is for batteries which are in the 100-160 Wh range and that below 100 Wh they seem to suggest that there is no limit. In the past there was a total Lithium metal limit based on xxx g/Wh, and I have 'come close to' that limit a few times when can=mera and laptop batteries were included. A 100 Wh battery = say 3.6V x 27+ Ah or about 10 x 2700 mAh 18650 cells. That would be a very large battery indeed by laptop standards - so there seems to be no sensible limit. Commented May 28, 2015 at 15:54
  • You can now get 97Wh batteries for dells. Both for the primary battery and the slice.
    – Phil
    Commented May 28, 2015 at 19:07

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