What No One Really Warns You About Before Flying

by: Nini
June 15, 2025

source: Pixabay

Okay so—here’s the thing. If you travel even semi-regularly and you’re lugging around your little tech ecosystem—phones, tablets, laptops, the inevitable dead-weight power bank—you’ve probably, at some point, wondered if the whole lithium battery situation is… like, a problem?

I didn’t really think much of it until this one time at JFK when my bag got flagged for “unidentified power sources” (which sounds way more dramatic than it was). Long story short, I had a couple spare batteries in a side pouch and apparently that’s not okay? Since then I’ve spiraled a bit into figuring out what you can and can’t get away with. It’s confusing. So this is basically me trying to untangle the mess for anyone else caught googling “lithium battery airport rules” at 2 a.m.

Why Everyone Freaks Out About Lithium Batteries on Planes

So, these batteries. They’re amazing little monsters—like, they cram a ridiculous amount of power into these small, tidy cells. Which is great until they… combust. Not even kidding. If they get too hot, or cracked, or mashed up against something metal, they can just… catch fire. And not like a cute candle flame. Think: tiny hellfire in your backpack.

That’s why you’ve got folks like the FAA and IATA setting rules. And they’ve gotten stricter over the years, especially since 2017-ish. Because here’s the problem: if a lithium fire starts in the cargo hold, nobody knows about it until smoke starts curling up through the cabin vents—and by then, yeah, no thanks. So that’s the whole idea: keep potential battery fireworks where someone can actually do something about it.

Okay But… What Are the Rules Exactly?

Right. The actual rules. I tried reading the official airline pages and ended up more confused, so here’s what I think the boiled-down version is:

• First off: carry-on. Like, always. That’s where your batteries should live. If it has lithium in it, keep it with you. Don’t check it unless you absolutely have to.
• If it’s a device with a removable battery (like a camera or a weird old laptop), and you are checking it for some reason, the battery needs to come out. And you bring the battery in your carry-on. The device can fly solo in the belly of the plane.
• Extra/spare batteries? Carry-on only. No exceptions. If you throw them in your checked bag, someone’s pulling you aside. Possibly with gloves.
• Size matters (ugh). Anything under 100 watt-hours (Wh) is cool. That includes basically all normal stuff—your phone, laptop, Nintendo Switch. Bigger batteries—up to 160 Wh—might still be allowed, but you need to check with the airline. Like, in advance. Don’t be the person arguing with TSA at the gate.
• Power banks count as spare batteries. So same rules apply: carry-on or bust.
• And if you have no idea what watt-hour rating your battery is, look at the label. It’s tiny, usually next to some absurdly unhelpful specs. If that fails, Google the model and hope someone else asked the same question on Reddit in 2019.

Packing Lithium Batteries Without Tempting Fate

Honestly, packing these things is mostly just common sense—but like, the kind of common sense you only develop after doing it wrong once. Here’s what I go by now:

• Try to keep the batteries in the original packaging. If that ship has sailed, at least throw them into a proper battery case. Loose batteries tumbling around your bag are a no.
• Cover the terminals. If you don’t know what that means, just tape the little metal ends with electrical tape. It helps prevent accidental contact with, like, your keys. Or spare change. Or that one rogue earring that lives at the bottom of every travel bag.
• Don’t fully charge them before flying. Weird, right? But a full charge increases the heat risk. Keep them around 40-70% if you can. Basically, don’t plug them in and then forget about them overnight.
• Switch everything off during takeoff and landing. I don’t know if it really matters, but I’ve read enough horror stories to just go with it. Better paranoid than smoky.
• And yeah—check for any swollen or cracked batteries before you leave. If something looks like it’s about to pop, just… don’t bring it.

What Happens If You Mess Up?

So, worst-case scenario: they find your rogue battery stash at security. You’ll probably get pulled aside. They might confiscate it, or worse, make you repack your entire bag at the side table while 37 people silently judge you.

In extreme cases, I’ve heard people get denied boarding. Which feels harsh, but… again, tiny fires at 30,000 feet. Airlines don’t love that risk.

Anyway. Don’t be sneaky. It’s not worth it. They’ve got scanners now that catch this stuff like it’s candy. Just assume they’ll find it. And then plan accordingly.

A Few Random (But Useful) Things I’ve Learned

• Don’t let batteries rub against metal. Like, not even for a second. If you’re tossing one into your bag, double-check there’s nothing conductive near it.
• Charge stuff before you get to the airport, not during. It’s not a great look to be juggling cords at the terminal outlets with sparks flying.
• Vape pens? Also lithium batteries. Also carry-on only. TSA loves confiscating those, apparently.
• And yeah—every airline has its own slightly-different, just-annoying-enough rules. So check their site before flying, especially if you’re doing international travel. Some are stricter than others, and weirdly inconsistent.

So yeah, lithium batteries. Magical energy bricks that make travel possible and slightly terrifying. Just pack smart, follow the rules, and don’t be the reason your flight attendants start sweating mid-flight.