A loose used tool battery is not an ordinary ground-mail parcel

The battery is the most valuable and most regulated part of the kit

In cordless tool resale, the battery is often worth as much as the tool, and sometimes more. It is also the part that carries the most risk and the most rules. Lithium-ion packs store a lot of energy. Damaged packs can overheat. Carriers regulate how they travel, and those rules are different for a battery packed alone, a battery packed with a tool and a battery installed in one.

That combination makes loose used batteries one of the easiest items to list badly. A pack that lights its charge indicator and runs a drill for a few seconds looks like a quick win. Whether you can describe it honestly and ship it legally is a separate question you need to answer before you buy.

Step 1: Identify the pack from its own label

Read and record from the battery itself:

• Manufacturer and battery platform (the tool system it belongs to).
• Model or part number.
• Chemistry (for example lithium-ion) and the nominal voltage and capacity printed on the label.
• Watt-hour rating if printed; if not, you can estimate it from the nominal ratings (see the worked example).
• Date codes or serial numbers, for your private records and recall checks.

Confirm compatibility through the manufacturer's information. A connector that looks like it fits, or a marketing voltage number, is not the same as the actual pack specification. Check the model against current CPSC recalls.

Step 2: Inspect, and know when to stop

Look at the pack under good light. Stop and do not charge, test or ship it if you see:

• Swelling, bulging or a case that no longer sits flat.
• Cracks, melted or scorched plastic, or a burnt smell.
• Corrosion or residue on the terminals.
• Signs it has been opened, rebuilt or repaired.
• A recall match for that model.

Do not open, rebuild or bypass a pack's protective controls, and do not improvise charging with an incompatible charger to demonstrate it works. Follow the manufacturer's guidance and your local rules for handling and disposing of damaged batteries.

Step 3: Describe what a short test can and cannot show

A charge indicator and a brief run on a tool are limited observations. They do not prove remaining capacity, cell balance, cycle history or that every protective function works. Write what you saw:

Keep standalone batteries separate from batteries packed with or installed in the tools they power. Placing an unrelated tool next to a battery is not a legitimate way to change how the shipment is classified.

Worked example: nominal ratings do not grant mailability

Take a hypothetical pack labelled 18 volts and 2 ampere-hours. Multiplying gives 36 watt-hours. That figure helps you read battery rules, which often refer to watt-hour thresholds, but it is not a product identification, a safety assessment or permission to ship.

USPS Publication 52, section 349.244, requires standalone lithium-ion batteries to be in their original sealed packaging, along with other limits and markings. The same section, as checked for this guide, also sets a 5-pound mailpiece limit, requires a DOT-approved lithium battery mark showing UN3480 plus surface-only wording, and limits these pieces to surface transportation outside the intra-Alaska exception. A loose used pack lacks the sealed packaging before any of those other conditions are reached. A ground-service label and taped terminals do not cure the mismatch. USPS also separately restricts damaged, defective or recalled lithium batteries, and the rules for used devices that contain batteries are not permission to mail a loose used pack.

Step 4: Decide the route before you list

Work this out before you buy, not after a buyer pays:

1. Local handover: often the simplest route for loose packs. Meet safely, let the buyer see the pack, and do not treat the handover as proof that the battery is safe.
2. Sold installed in or packed with its tool: a different configuration with different rules. Read the current Publication 52 provisions for that configuration.
3. Another carrier: has its own requirements. Read them; do not assume they mirror USPS.
4. Pass: a legitimate business decision when no responsible route exists.

The restricted items guide and the used tools guide cover the surrounding decisions.

Step 5: Write the listing like a specification sheet

Lead with platform, model, voltage and capacity as printed. Then the observations from Step 3, the inspection result, what charger you tested with (and that it is not included, if it is not) and the delivery method you are actually offering.

Common mistakes:

• Promising shipping on a loose used pack.
• Writing "full capacity" from a charge indicator.
• Charging a pack you found swollen.
• Bundling a random tool to change the shipping classification.

Do not promise shipment first and investigate the battery later. If no responsible permitted transfer route exists, pass rather than treating a local handover as proof of safety.