Yes, installed button batteries may travel in checked bags, yet spare loose cells must ride in carry-on with terminals taped or in retail packs.
Button cells power watches, car remotes, glucometers, key fobs, and dozens of pocket-size gadgets. They look harmless, yet they still hold lithium metal and carry fire risk if the energy shorts. Air regulators draw a clear line: tiny cells inside devices can sit in the hold, while spares must ride with you. This guide walks through the rules, weight limits, airline caveats, and smart packing habits so you avoid check-in trouble or gate bag searches.
The advice below follows the United States TSA battery rules, Federal Aviation Administration (FAA) PackSafe notices, International Air Transport Association (IATA) guidance, and similar material from other aviation bodies worldwide.
Battery Categories And Where They May Travel
| Battery Type | Installed In Device | Spare / Loose |
|---|---|---|
| Button cell (lithium metal ≤ 0.3 g) | Checked or carry-on | Carry-on only — pack in original blister or tape both sides |
| AA / AAA lithium metal (> 0.3 g) | Checked or carry-on | Carry-on only; 2 g lithium total per cell cap applies |
| Power bank / loose Li-ion ≤ 100 Wh | N/A (classed as spare) | Carry-on only; no limits on count, but each must stay below 100 Wh |
Why Button Cells Get Special Treatment
Lithium content is the regulator’s yardstick. A coin cell under 0.3 g lithium metal poses lower heat output if damaged, so agencies allow such cells in the cargo hold when installed in equipment. Larger cells or loose packs heat faster during short-circuit, which is harder to detect inside a hold. That hazard led to the outright cabin-only rule for loose lithium cells and power banks.
Rules Snapshot: United States And Beyond
TSA And FAA
The TSA screens every bag at U.S. airports, following the FAA PackSafe chart. The chart states that spare lithium metal or lithium-ion cells must never be in checked bags. Officers may remove power banks or coin cell cards left inside suitcases and hand them back at the desk. Fines for undeclared hazardous goods can top four figures, yet most travelers only face delays while agents unpack their cases.
IATA — The Airline Rulebook
IATA’s Dangerous Goods Regulations guide carriers worldwide. Section 2.3A calls button cells “lithium metal batteries contained in equipment” and green-lights them in the hold when below 0.3 g. The same document reinforces that spare units are “UN 3090” goods, permitted only in carry-on after short-circuit protection.
Australia’s CASA Example
Australia adopted an almost identical stance. CASA reminds passengers that “small and flat lithium button cells… are far more benign” yet still asks fliers to keep spares in the cabin. Local carriers often require a tape barrier on each spare to pass check-in.
Can You Pack Button Batteries In Checked Luggage?
Yes, though the item must meet three points:
- The cell sits inside its device; no loose pairs or multipacks.
- Lithium weight ≤ 0.3 g per cell, which covers common CR2032, CR2025, and similar watch cells.
- The device cannot power itself on during transport, so switch off or use travel locks.
Meeting those conditions, you can hand the item to agents at drop-off. They may ask you to prove power-off status; a quick removal of the battery tab does the job.
Loose Coin Cells: Cabin Only
Loose cells slip between other items, and metal keys or coins can bridge the poles. That bridge turns the coin cell into a pocket heater that may reach 600 °F before bursting. Flight deck crews can handle smoke in the cabin with hand extinguishers, yet cannot reach fire sources locked in an aluminum container below. That difference drives the strict cabin-only rule.
Packing Loose Button Batteries The Right Way
Follow these steps each time you fly with spare coin cells:
- Leave them sealed inside retail blister when possible. The molded plastic keeps poles apart.
- Otherwise, tape both sides with non-conductive tape, then slip pairs into mini zipper pouches.
- Use a clear label: “Spare coin cells — lithium metal” so gate staff spot them fast.
- Place the pouch in the same bag as power banks to remind yourself of cabin rules.
Device Examples And Common Pitfalls
Watches And Fitness Bands
Many quartz watches still rely on silver oxide or lithium coin cells. If you plan to drop an heirloom piece in your checked suitcase, pull the crown to stop the movement. The crown trick reduces chance of motor stall — and saves battery life.
Medical Sensors
Continuous glucose monitors (CGMs) hold sealed coin cells. Airlines classify a CGM as a medical device, so it may stay on your arm along with backup sensors in carry-on. Do not ship spare sensors in the hold.
Car Remote Fobs
A fob can wake up if luggage shifts, hold a button down, and drain the cell. Crew announcements often list “key fobs sounding in the cabin.” To avoid that, pop the coin cell out and seal it near you.
Airline-Specific Add-Ons
While global regulators write baseline rules, airlines can add stricter clauses.
Virgin Australia After 2025 Power Bank Incident
A cabin fire tied to a power bank led Virgin Australia to review its lithium policy. The carrier now places bag bay bins at gates for last-minute lithium drops. Button cells below 0.3 g remain allowed in checked hold once installed.
Asian Flag Carriers
Some Asian airlines request no lithium batteries in the hold even if installed. Staff at Tokyo-Haneda or Seoul-Incheon may hand out plastic bags for watches. Check the dangerous goods page on your booking email for such alerts.
Quick Reference Checklist Before Departure
| Item | Where It Goes | Action |
|---|---|---|
| Watch with installed CR2032 | Checked bag or carry-on | Pull crown or place in travel case |
| Spare CR2032 blister card (5 cells) | Carry-on | Keep in blister; store at top for screening |
| Loose single coin cell | Carry-on | Tape both poles, zip pouch |
Preventing Damage Or Drain During Travel
Coin cells handle cold cargo holds, yet rapid swings from terminal heat to high-altitude chill can trigger condensation. Moisture on contacts leads to micro-corrosion and early drain. Store gadgets in soft cloth bags, adding a silica packet to absorb vapor.
Knock shocks pose another issue. Hard shell luggage common on long trips can smack against conveyor rollers. A jolt may free the contact spring inside a small device. A folded tissue behind the battery door stops movement. That tiny buffer brings peace.
What Happens If Agents Spot Loose Cells In Checked Bags?
If a suitcase passes X-ray and screeners see coin cells rolling near metal, they flag “anomaly.” Bags move to a secondary belt where officers open them. You might receive a tag noting removed batteries or a doorbell at the gate asking you to open the case. The process slows boarding and nobody loves repacking under pressure.
International Transfer Considerations
Connecting flights add complexity. A spare battery bag that meets U.S. limits may clash with stricter airport transits where any lithium in the hold is forbidden. When in doubt, keep every loose cell near you. Cabin staff can handle incidents fast, and you skirt customs queries during re-screen.
Disposal Abroad
Never dump used coin cells in hotel trash. The steel shell can spark against metal bins. Many airports feature receptacles near customs exits. Look for a small red battery logo. Drop cells there free of charge. European terminals enforce WEEE rules, while U.S. airports partner with Call2Recycle boxes.
Recap
Installed coin cells under 0.3 g lithium, such as CR2032 or CR2025, may chill in the belly of the plane. Loose spares belong in the cabin, taped or in original packaging. Rules come from TSA, FAA, IATA, and national regulators such as CASA, and airlines can tighten them. Pack smart, label clearly, and watch agents sail your bag through without pause. Your watch keeps time, your glucose sensor stays ready, and the cargo hold stays cool.