9.2 Lithium Batteries and Spare Cells

9.2 Lithium Batteries and Spare Cells

Quick answer: FAA PackSafe and TSA's Power Banks listing agree on the spare-cell rule: spare (uninstalled) lithium ion and lithium metal batteries, including power banks and cell phone battery charging cases, must be in carry-on baggage only. They are prohibited in checked luggage. Protect terminals from short circuit. If a carry-on is checked at the gate or planeside, remove those spares and keep them in the cabin. Devices that contain lithium should be in carry-on; if they go in checked baggage they must be completely powered off and protected from unintentional activation. External medical devices with lithium must be carry-on on TSA's medical page.

Lithium batteries are everyday objects and hazardous materials. FAA PackSafe states that all lithium ion batteries can overheat and enter thermal runaway, including after damage, water exposure, overcharge, improper packing, or a manufacturing defect. Flight crews train for cabin battery fires. Passengers should notify crew immediately if a battery or device is overheating, expanding, smoking, or burning. That is why spare cells stay where crew can reach them — in the cabin — not in a closed hold.

This section is public FAA/TSA packing logic for the TAB and the checkpoint. It is not SSI. It is not an airline's stricter house rule. Many carriers cap how many power banks a passenger may bring. Tell travelers to check the airline, then still apply the federal floor below.

Spare versus installed — the first split

FAA draws a bright line:

• Spare / uninstalled lithium metal and lithium ion batteries, including power banks, portable rechargers, and cell phone battery charging cases, are always prohibited in checked baggage and must be in carry-on.
• Installed lithium batteries (the cell inside a laptop, phone, camera, tablet, watch, or similar portable electronic device) follow the portable electronic devices entry: those devices should be in carry-on. If they are in checked baggage, they must be completely powered off and protected to prevent unintentional activation or damage. Devices capable of generating extreme heat need the heating element, battery, or other components mitigated.

A power bank is not "a device" for this split. TSA's Power Banks page is Carry-on: Yes / Checked: No. Portable chargers or power banks containing a lithium ion battery must be packed in carry-on bags. Spare lithium batteries, which include both power banks and phone chargers, are prohibited in checked luggage. A phone in a charging case is carrying a spare as far as PackSafe is concerned. Do not check the case because "it is attached to a phone."

If the traveler's carry-on is gate-checked or checked planeside, FAA is explicit: all spare lithium batteries and power banks must be removed from the bag and kept with the passenger in the aircraft cabin. The spare-cell rule does not vanish because the bag started as a carry-on. The hold is still the hold.

Short-circuit protection

PackSafe requires two protections that candidates skip: protect batteries from damage, and protect terminals from short circuit. Terminals (usually the ends) must not contact other metal. Published methods include:

• Leaving batteries in retail packaging
• Covering terminals with tape
• Using a battery case or a camera-bag sleeve
• Putting them snugly in a plastic bag or protective pouch

Loose spare cells in a pocket with keys, coins, or jewelry are a short-circuit setup, not a packing method. FAA notes that leaving a rechargeable battery in a wall charging unit is not considered short-circuit protection for dry-cell spares. Teach travelers to cover the contacts, not to dump cells in a gadget pouch and hope.

The regulation PackSafe cites for these passenger exceptions is 49 CFR 175.10(a)(18). You do not need the section number on the TAB. You do need the operational facts it backs: cabin for spares, protect the terminals, size limits.

Size and quantity limits

FAA PackSafe (page last updated August 11, 2026) publishes the consumer bands:

Those typical limits cover nearly all personal-electronics cells. Watt hours on newer lithium ion packs are marked on the battery. PackSafe's tip: Wh = voltage × amp-hours (Ah).

Quantity: there is no general numeric cap for most personal-use batteries, but they must be for use by the passenger. Batteries carried for sale or distribution (vendor samples) are prohibited. The two-spare cap applies to the larger 101–160 Wh (or 2–8 g lithium metal) band. Airlines, domestic and international, may be stricter, including how many power banks they allow regardless of Wh. Send remaining questions to the air carrier and to PackSafe, not to a forum rumor.

TSA's lithium batteries with more than 100 watt hours page matches the spare rule: Carry-on Yes (special instructions) / Checked No, airline approval for up to two spare 101–160 Wh lithium ion or 2–8 g lithium metal cells, covering extended-life laptop batteries and some professional audio/visual packs.

Installed devices, medical lithium, and damaged cells

FAA's portable electronic devices page (updated September 23, 2025) says devices containing lithium metal or lithium ion batteries should be carried in carry-on baggage. Cabin crew can fight a fire they can see. If a lithium-powered PED is nonetheless in checked baggage, it must be completely powered off — not sleep mode — and protected from turning on or being crushed. Electronic smoking devices are a separate PackSafe entry and are always prohibited in checked baggage; they are not a "device containing a battery, so maybe the hold" exception.

TSA's External Medical Devices listing uses a stronger verb for medical lithium: devices containing lithium metal or lithium ion batteries must be carried in carry-on baggage. Most other consumer electronic devices containing batteries are allowed in carry-on and checked, subject to FAA rules. An insulin-pump spare, a wearable-stimulator spare, or a portable concentrator battery is not a "check it so it is safe" item. Cabin. Section 9.3 covers how those devices are screened. This section covers how they are packed.

Damaged or recalled batteries and battery-powered devices that are likely to create sparks or a dangerous evolution of heat must not be carried aboard an aircraft in carry-on or checked baggage unless the damaged or recalled battery has been removed or otherwise made safe. Point travelers to the CPSC recalls list and the airline. Tape on a swollen pack is not "made safe."

X-ray aptitude and a realistic pack

On an image, spare lithium often reads as small dense bricks or cylinders, sometimes in a plastic case, sometimes loose among cables. A power bank is a dense rectangular block with ports. An installed laptop battery sits inside the laptop slab from section 9.1. Do not treat every dense brick as a permitted installed cell. If it is uninstalled, public packing logic is carry-on only, terminals protected.

Realistic scenario: A photographer checks a suitcase with two spare camera batteries in a zipper pocket, a 20,000 mAh power bank, a laptop with its battery installed, and a recalled hoverboard charger the traveler "taped up." The spare camera batteries and the power bank are spare lithium: they must come out of the checked bag and into carry-on, terminals covered. The laptop should be carry-on; if it stays checked it must be powered off and protected from activation. The recalled item that can heat or spark does not fly unless the battery is removed or otherwise made safe. At the gate, when the carry-on is tagged to go in the belly, those same spares must be pulled again and walked onboard. The final decision rests with the TSA officer at the checkpoint; the airline still enforces watt-hour and quantity limits on the aircraft.