Buyers often treat a batch report as a formality: a page of numbers that arrives with the shipping documents. It is actually a record of a statistical decision, and reading it properly takes about five minutes.
What AQL means in one paragraph
AQL (acceptable quality limit) is the defect rate that a sampling plan is designed to accept. It is not a promise that the batch has that defect rate; it is a rule that says “if the sample contains more than this many defects, reject the batch”. Different defect classes get different limits: a cosmetic flaw may be accepted at a looser level than a safety-related fault, which is usually not sampled at all but tested on every unit.
The three lines to look at
Sample size — how many units were pulled, and from where. A sample drawn only from the first cartons off the line is not representative.
Defect classification — critical, major, minor, and which faults were assigned to each. This is where the meaning lives: a loose plug is major, a print blemish is minor.
Accept/reject numbers — for that sample size, the plan’s threshold. A report that lists defects but not the threshold is incomplete.
What full inspection covers
For chargers, function and safety testing are usually 100%: every unit is powered, loaded and measured for output. Destructive tests — temperature rise, plug retention after repeated insertion, drop — consume units and therefore run on samples. That combination is normal and worth understanding before asking why not everything is tested.
What to ask when a batch fails
Ask three things: which defect class failed, on which units, and what is being done with the batch. The right answer describes a rework path with a re-test, not a discount. A discount on a failed safety-related test is not a commercial decision, it is a liability transfer.
Keeping the record
File the report against the date code. Six months later, when a customer reports a fault, the report is what tells you whether the problem is systemic or a single unit — and that difference decides whether you need to check other shipments.