Lithium Battery Listings on Amazon: Wh Marking, UN 38.3 and Hazmat Review

A lithium battery turns an ordinary electronics listing into a dangerous-goods listing. That is not a figure of speech: the moment a product contains a lithium cell, Amazon routes it through dangerous-goods review, the Department of Transportation's hazmat rules apply to how it ships, and the capacity figures in your bullets become regulated facts rather than selling points. Sellers who treat the battery as a spec line discover this when FBA inbound stalls with no obvious error, or when a power bank listing is removed for an mAh figure the product cannot physically hold.

This guide covers the three layers: what the transport rules require, what Amazon asks for in the listing, and how the figures on your battery marking, in your attributes and in your copy have to agree.

The transport rules behind it all

The governing regulation is 49 CFR 173.185, the hazmat rule for lithium cells and batteries. Three of its requirements reach straight into an Amazon listing:

• Tested design. Every lithium cell or battery type must be of a design proven to meet the UN Manual of Tests and Criteria, sub-section 38.3. Under 173.185(a)(3), every manufacturer and every subsequent distributor must make the UN 38.3 test summary available to others in the supply chain on request. That includes you, the seller, and it has been mandatory in 49 CFR since 1 January 2022. One summary per cell or battery model.
• Wh marking. Under 173.185(a)(5), lithium-ion batteries and cells must be marked with the watt-hour rating on the outside case. The requirement has applied to all lithium-ion batteries since 10 May 2024; small batteries excepted under 173.185(c)(1)(i) have carried the mark since 2016. Packages carry the lithium battery mark under 173.185(c)(3), and fully regulated shipments carry the Class 9 label under 173.185(c)(5).
• Thresholds that depend on the true rating. The 20 Wh per cell and 100 Wh per battery limits decide whether a shipment is excepted or fully regulated. A battery that is really 148 Wh but listed as "20,000 mAh" with no voltage is misclassified from the start.

PHMSA keeps an overview at phmsa.dot.gov/lithiumbatteries. None of this is Amazon policy. It is federal transport law that Amazon, as a shipper and warehouse operator, enforces through its listing data.

What Amazon's dangerous-goods review wants

Listings with lithium batteries go through dangerous-goods review before FBA will accept them, and the review runs on two inputs: a document and a set of attributes.

The document is a battery safety data sheet (SDS), or the Amazon exemption sheet for products that qualify. It needs to show composition, Wh rating, cell count and packaging. Amazon's dangerous goods identification guide describes the process at a high level; the detailed hazmat pages sit behind the Seller Central login.

The attributes are the battery fields on the listing. The ones the electronics rule pack treats as required when a lithium battery is present:

• battery.cell_composition: the chemistry (lithium-ion, lithium polymer, LiFePO4, lithium metal).
• lithium_battery.energy_content and its unit: the Wh rating Amazon uses for hazmat classification.
• supplier_declared_dg_hz_regulation: the dangerous-goods declaration every listing must carry (not applicable, GHS, storage, transportation or other). This drives whether a review happens at all.

Also read, when the report carries them: lithium battery weight, packaging (contained in equipment, packed with equipment, or standalone), number of lithium-ion and lithium-metal cells, batteries required and included, and whether the battery is replaceable.

The failure mode is quiet. Review blocks FBA until the documents are accepted, and nothing on the listing page says so. A seller sees stock that will not check in and a listing that looks live, and spends a week on the wrong problem. If you sell anything with a built-in rechargeable cell, assume the review applies and have the SDS and the UN 38.3 summary ready before you create the ASIN.

Your three battery figures must agree

Amazon reads battery figures from three places: the battery marking in your images, the attributes, and the body copy. They need to tell the same story.

The arithmetic is simple. mAh times nominal voltage, divided by 1,000, equals Wh. A 10,000 mAh power bank built on 3.7 V cells is 37 Wh. The classic error is to double it: a listing says 10,000 mAh and 74 Wh, because someone multiplied by the 5 V output or added two cells twice. The marking on the case says 37 Wh, the attribute says 74 Wh, and the listing is now claiming a battery that would be in a different transport bracket.

The checks a scan runs when a battery marking is visible in the images:

1. The Wh on the label against the Wh in the listing and in lithium_battery.energy_content.
2. mAh times V divided by 1,000 against the stated Wh, within about ten percent.
3. Chemistry and cell count on the label against the attributes and copy.

Each disagreement is a finding, quoting the listing figure next to the marked one. A listing Wh that the mAh and voltage cannot support is a finding even when no label is visible. This is why the pack asks you to upload the battery marking as a label image: it is the reference document, the way a Supplement Facts panel is for a supplement, and our guide to matching the detail page to the panel describes the same discipline in another category.

Capacity claims that fail on physics

Overstated capacity is its own problem, separate from consistency. Amazon removes power banks with overstated mAh, and under FTC Act Section 5 an objective capacity figure is a claim that needs a reasonable basis.

The plausibility checks the rule pack applies:

• Energy density. Current lithium-ion cells store roughly 200 to 260 Wh per kilogram. A power bank therefore cannot exceed about 12 Wh, around 3,200 mAh at 3.7 V, for every 60 g of total weight. A "50,000 mAh slim power bank, 150 g" is physically impossible.
• Airline language. A battery over 100 Wh is not "airline approved" without airline permission, and over 160 Wh is forbidden as carry-on. "20,000 mAh, 3.7 V, 148 Wh, airline approved" contradicts itself.
• mAh without voltage on a multi-cell pack. For a 48 V e-bike battery or a portable power station, mAh alone is meaningless. State the Wh, or the mAh with the pack voltage.
• Marketing mAh versus cell mAh. Some brands quote the cell capacity (what the cells hold) and others quote the output capacity at 5 V. Pick the one that matches the marking, and say which it is.

Take a fictitious listing that reads "20,000 mAh, 3.7 V, 148 Wh, airline approved". The arithmetic gives 74 Wh, so the Wh figure is doubled, and even if 148 Wh were right it would not be airline approved without permission. Two findings from one bullet. Fix the figures, not the wording.

Power banks and standalone batteries: lab reports and TIC

Beyond hazmat, Amazon gates two sub-types on safety certification.

Power banks and portable power supplies need an ISO 17025 accredited lab report to UL 2056, or to IEC/UL/CSA 62368-1 plus 62133-2, or to 62368-1 plus UL 2054. Since 12 December 2025, that testing or validation has to go through an Amazon-approved testing, inspection and certification (TIC) provider.

Standalone rechargeable lithium batteries (replacement packs, 18650 and 21700 cells, LiFePO4 packs) need a report to UL 2054, UL/CSA 62133 or IEC 62133-2, with UL 1642 for bare cells. Amazon extended TIC verification to lithium batteries in 2026.

If your listing says "UL certified" without the standard, that is a separate finding; our post on waterproof, military grade and UL claims covers why.

Disposal and stewardship cues

Two smaller rules round out the battery picture. The federal Battery Act, 42 USC 14322, requires Ni-Cd and small sealed lead-acid batteries, and the products containing them, to carry the three-chasing-arrows symbol, the chemistry and the statement that the battery must be recycled or disposed of properly, and to be easily removable. A listing that describes a Ni-Cd pack as non-removable, or tells buyers to throw a dead rechargeable in the trash, is flagged.

Several states now run battery stewardship programs: California's AB 2440, Illinois (from 1 January 2026), Washington, Vermont and DC. Retailers may not sell batteries from producers outside an approved plan. A listing does not need a recycling statement, but a seller shipping standalone batteries into those states needs the producer's stewardship membership on file.

The battery file for each ASIN

What a complete lithium battery listing has behind it:

• UN 38.3 test summary for the cell or battery model.
• Battery SDS or Amazon exemption sheet.
• Battery marking photo showing Wh, chemistry and warnings.
• Lab report or NRTL certificate for power banks and standalone batteries, through a TIC provider where required.
• Attributes filled: composition, Wh, cell count, weight, packaging, dangerous-goods declaration.
• Copy whose mAh, V and Wh agree with the marking.
• Stewardship membership evidence if standalone batteries ship to a program state.

The electronics category carries more required documents than most, and the battery ones follow the battery rather than the category: a cordless drill filed under Tools or a heated mug with a lithium cell picks up the same list. Verid8 tracks which of these each ASIN has on file, compares the marked figures against the attributes and copy, and flags the capacity claims that the arithmetic cannot support.