How many units must we send to a test lab for charger certification?

Main answer · Wecent Editorial Team

Short answer: There is no single number. The lab decides based on the standards and tests, since some tests are destructive and some tests run in parallel. Expect to send several units for the safety standard, extra units for radio or energy tests if they apply and spares for retests. Ask the lab for a written sample list before you ship, and send a few extras.

Why the number varies

Each test standard needs samples, and some tests damage the units, such as abnormal operation, impact, strain and thermal tests. Labs run several tests at the same time, so they need enough units to avoid long delays.

What affects the quantity

• Standards. Safety, radio, energy and others each have their needs.
• Product variants. Plug types, colours and ratings may need separate samples or additional units.
• Destructive tests. Units that are tested to failure cannot be reused.
• Component samples. Some critical parts may be requested separately, such as plastic samples or cables.
• Retests. Spares avoid delays if a unit fails or is damaged.

How to ask

1. Send the lab the product description, ratings, variants and target markets.
2. Ask for the list of tests and the sample quantity for each.
3. Ask whether extra material samples are needed.
4. Ask for the lead time and the address, and for packing advice.

Prepare the samples

• Use production-intent units, not hand-built prototypes.
• Label each unit with a unique number.
• Include the bill of materials, circuit diagram, label drafts and manuals.
• Make sure each unit is working.

Budget for extras

Send a small number of extra units, because the cost of delay is higher than the cost of a few more chargers.

Keep records

Record which units went to which test and the results. Keep a few identical units as references.

Quick summary

Ask the lab for a written list, send production units with documents and add a few spares.

Example sample plan

For one charger model with two plug variants and one colour, a lab might ask for a set of units for the main safety tests, some further units for abnormal-operation and strain tests, and some for temperature and drop tests. You may be asked to supply the plastic and cable separately. The lab’s list will say exactly what is needed.

Where this answer says to confirm with Wecent, the detail is not published on the product page and has to come from the datasheet or the factory. General facts come from the regulators, standards bodies or device makers named in the text.