Written and reviewed by

Andrew McGaffey

CPAP Battery Expert at EXP PRO

View author profile →

Most airport battery problems start with one question: “How many watt-hours is this?” Here’s what employees are checking, why an allowed battery can still be delayed, and how to handle the conversation without losing your battery or your flight.

By Andrew McGaffey, EXP PRO
Updated July 24, 2026

Most airport battery problems do not begin with a dramatic confiscation. They begin with a simple question:

“How many watt-hours is this?”

At EXP PRO, we’ve heard from CPAP travelers whose batteries were questioned even though the battery fell within the federal size limit. The problem at the counter is often not the rule itself. It is whether the employee can quickly verify the battery’s capacity, how it is packed, and whether the airline approved it.

Airports move fast. If an employee sees an unfamiliar black box with lithium cells inside, they may stop the bag until they know exactly what they are looking at.

Having the right battery is important. Being able to prove what it is can matter just as much.

The battery rules airport employees are trying to apply

For rechargeable lithium batteries on U.S. passenger aircraft, the most important number is the battery’s watt-hour rating:

• 100Wh or less: Generally allowed in carry-on baggage.

• 101Wh to 160Wh: Requires airline approval and is generally limited to two spare batteries per passenger.

• Over 160Wh: Not allowed on passenger aircraft.

Spare lithium batteries and power banks must remain in the cabin. They cannot be placed in checked baggage, and their terminals must be protected from damage and short circuits. Airlines can also set stricter limits than the federal baseline.

That means a CPAP battery can comply with the general federal size limit and still be stopped for review. The employee needs to identify the battery, find its watt-hour rating and determine whether airline approval is required.

Where your CPAP battery may be questioned

A CPAP battery can be questioned at the airline counter, the TSA checkpoint or the boarding gate. These are separate parts of the airport process, and the employee at each location is looking for something slightly different.

At the airline counter

This is where approval for a larger battery is most likely to come up.

A lithium battery between 101Wh and 160Wh requires the airline’s approval. An employee may:

• Look for the watt-hour rating on the battery

• Check your reservation for an approval note

• Review an approval email

• Ask what equipment the battery powers

• Call a supervisor or another airline representative

Airline approval is not automatic. Federal rules allow an airline to approve a battery in this range, but an airline may apply a stricter policy or decline to carry it.

This is why a screenshot of the general FAA rule is not as useful as written approval from the airline you are actually flying.

At the TSA checkpoint

TSA is screening your CPAP equipment and carry-on bag for security concerns.

CPAP, BiPAP and APAP machines may remain in their carrying cases for X-ray screening, although an officer can ask you to remove the machine. Medical equipment and supplies may also receive separate inspection or additional testing.

Your battery may be pulled aside because:

• The X-ray image is unclear

• The watt-hour label is difficult to read

• The battery is unusually large

• Cords or other electronics are packed around it

• The casing appears damaged or altered

• The officer wants a closer look at the ports

Additional screening does not necessarily mean the battery is prohibited. The officer may simply need to identify it and get a clearer view.

Passing through TSA does not replace airline approval. TSA handles checkpoint screening. The airline is the party that approves a 101–160Wh battery for carriage on its flight.

At the boarding gate

The gate is the worst place to discover that the airline cannot verify your approval. Boarding may already be underway, and there is less time to call customer service or find someone familiar with the policy.

A gate agent may question the battery after noticing it in your bag, reading a note from another employee or asking you to gate-check your carry-on.

If your carry-on bag is taken at the gate and placed in the cargo hold, remove the CPAP battery first. Spare lithium batteries and power banks must remain with you in the cabin.

What the employee is trying to confirm

Most airport battery reviews come down to a few basic questions:

1. What is this battery used for?

2. What is its watt-hour rating?

3. Is it 160Wh or less?

4. Is it packed in carry-on baggage?

5. Are its ports protected?

6. If it is over 100Wh, did the airline approve it?

The employee may not use the phrase “watt-hours.” They might ask for the battery size, power rating, lithium rating or capacity.

Point to the Wh marking printed on the battery. Do not begin by explaining milliamp-hours, cell voltage or battery chemistry unless the employee asks.

A clear watt-hour label matters more than many travelers realize. If the label is covered, damaged or unreadable, the employee may not be able to verify that the battery is below the limit.

What happens after the first question

There are several ways the review can go.

The battery is cleared

The employee sees the watt-hour rating, confirms that the battery is packed correctly and allows you to continue.

When the battery is clearly labeled and the approval is easy to find, the entire conversation may take less than a minute.

The battery receives additional screening

The battery may be removed from your bag, visually inspected, tested or sent through the X-ray again.

Stay nearby and answer the questions directly. Do not start unpacking documents unless the officer asks or seems uncertain about the battery.

A supervisor is called

A larger CPAP battery is less familiar than a phone charger. The first employee may not know the policy well enough to make the decision alone.

A supervisor may review:

• The battery label

• The watt-hour rating

• Your airline approval

• The battery specification sheet

• The airline’s restricted-items policy

Having a supervisor called is inconvenient, but it is often a better outcome than having an employee make a quick decision based on incomplete information.

The battery is refused

A battery may be refused when:

• It is over 160Wh

• Its watt-hour rating cannot be verified

• Required airline approval was not obtained

• The airline has a stricter policy

• The battery appears damaged, swollen or recalled

• The battery is packed in checked luggage

Damaged or recalled lithium batteries that could spark or generate dangerous heat are not allowed aboard an aircraft unless they have been removed or otherwise made safe.

Documentation can resolve a question about an allowed battery. It cannot make a prohibited battery acceptable. A 307Wh battery is still over the passenger-aircraft limit even if it has completed UN 38.3 testing.

Why written airline approval matters

For batteries between 101Wh and 160Wh, saying “the FAA allows it” does not fully answer the employee’s question.

The FAA rule permits carriage with airline approval. It does not require every airline to approve every battery.

Written approval gives the airport employee something specific to review. The best confirmation identifies:

• The airline

• Your battery model

• The exact watt-hour rating

• Your travel date or reservation

• Permission to carry the battery in the cabin

Save the full email to your phone so it is available without internet access. Take screenshots as a backup and print a copy.

A general message saying “CPAP machines are allowed” may not be enough. The CPAP machine and the external battery are two separate items under airport rules.

The useful response is one that specifically confirms approval for your external battery and its watt-hour rating.

What UN 38.3 paperwork proves

A UN 38.3 test summary shows that the battery design completed the lithium-battery tests required for transportation.

PHMSA states that lithium cells and batteries offered for transportation must have passed the applicable tests in Section 38.3 of the United Nations Manual of Tests and Criteria. Manufacturers and subsequent distributors must make the test summary available upon request.

This document can help show that the battery is a tested commercial product with a traceable model, manufacturer and test record.

It does not serve as airline approval, and it does not override the watt-hour limit.

For an airport review, the most useful document set is:

• Written airline approval

• A battery specification sheet showing watt-hours

• The UN 38.3 test summary

• A one-page airline reference sheet

A CPAP prescription or doctor’s note can help explain why you are traveling with the equipment. It does not replace approval for a lithium battery over 100Wh.

EXP PRO travelers can download the supporting documents from the EXP PRO Travel Documents page and view the EXP48PRO UN 38.3 documentation.

What to say when your CPAP battery is questioned

Keep your answer short. An airport counter is not the place for a detailed explanation of lithium battery chemistry.

Try this:

This is an external battery for my CPAP machine. It is rated at 153.6 watt-hours and is packed in my carry-on with the ports protected. I have written airline approval, the battery specification sheet and the UN 38.3 test summary.

Point to the watt-hour rating and show the approval.

If the employee still says the battery is not allowed, ask:

Is the concern the watt-hour rating, the airline approval or another part of the battery policy?

This gives the employee a specific question to answer. It can also reveal whether you are dealing with a real restriction or a misunderstanding.

When necessary, politely ask whether a supervisor can review the battery and your documents.

Avoid relying on the phrase “TSA approved.” Getting through TSA screening is not the same as receiving the airline approval required for a battery over 100Wh.

What not to do

Do not hide the battery in your bag or describe it as something else.

Do not move it into checked luggage to avoid the question.

Do not arrive with a battery over 100Wh and assume that a printout of the FAA rule is the same as airline approval.

Do not bring only a link to a product page that depends on airport Wi-Fi. Save your documents directly to your phone and carry printed copies.

It is also a bad idea to argue with the employee or demand that the battery be accepted. A calm request for the exact reason and a supervisor review is far more likely to help.

What happens if the final answer is no?

If the airline makes a final decision not to carry the battery, there may not be a quick solution at the gate.

Your practical options may include:

• Returning the battery to your vehicle

• Leaving it with someone who is not traveling

• Taking it to a safe off-airport location

• Changing your travel plans

Do not place the battery in checked baggage.

Do not put it into ordinary mail or an airport parcel box without confirming the carrier’s hazardous-material shipping requirements. Lithium batteries are regulated for shipping as well as passenger travel.

The approval issue is much easier to solve before the day of your flight.

How the rules apply to EXP PRO batteries

EXP48PRO APEX

The EXP48PRO APEX is rated at 153.6Wh. It is below the 160Wh passenger-aircraft ceiling, but because it exceeds 100Wh, airline approval is required.

The battery should remain in your carry-on baggage with its ports protected. Bring the written approval, specification sheet and UN 38.3 test summary.

EXP96PRO APEX

The EXP96PRO APEX is rated at 307.2Wh. It exceeds the passenger-aircraft limit and should not be brought to the airport as a carry-on CPAP battery.

The EXP96PRO is intended for camping, RV travel, road trips, off-grid CPAP use and home backup rather than airline travel.

Before leaving for the airport

Check the battery while you still have time to fix a problem:

• Make sure the watt-hour rating is visible

• Inspect the battery for damage or swelling

• Protect the ports from contact with metal

• Pack the battery in your carry-on

• Save your airline approval offline

• Bring the specification sheet

• Download the UN 38.3 test summary

• Print a second copy of the documents

• Remove the battery if your bag is gate-checked

Most travelers who are questioned are not facing a dramatic confrontation. An employee is trying to verify an unfamiliar lithium battery while passengers are waiting and a flight is getting ready to leave.

Make the important information easy to find. The visible watt-hour rating, written airline approval and battery documents can turn a stressful airport delay into a short conversation.