ACOUSTIC EVIDENCE · ENGLISH BUYER GUIDE
Ask what a charger noise figure actually describes
By Xiaochong Energy · · 6 min read
A hotel, commercial car park or fleet depot buyer may receive several charger quotations with a noise figure beside the power rating. That single number is not a complete comparison. Before selecting equipment for a noise-sensitive location, build an evidence request that connects the proposed configuration, its operating conditions and the site's acceptance process.
This is a procurement checklist, not an acoustic design, noise-limit assessment or installation approval. It makes no Xiaochong decibel, quiet-mode or noise-certification claim. Qualified local professionals must determine applicable requirements and assess electrical, thermal, structural, accessibility and acoustic aspects using exact-model documentation and site evidence.
1. Define the decision before asking for a number
State where the charger is proposed, when it may operate, which nearby spaces matter to the project and who is responsible for site assessment. Describe the intended number of units and charging arrangement without assuming that a single-product report represents the complete installation. A supplier can then identify available product evidence; the site reviewer can identify what further information is needed.
The UK Health and Safety Executive's purchasing guidance recommends consistent supplier questions and distinguishes standard test conditions from intended use. It also cautions that equipment noise data alone is only a guide. We use that purchasing principle here, not UK workplace rules as a worldwide charger approval.
Ask for the document before the selection deadline. If it is unavailable, record “evidence not supplied” and agree the next decision gate. A blank field is neither a zero-noise result nor permission to invent a value.
2. Separate the reported quantities
Sound power describes acoustic output from a source; sound pressure describes the acoustic condition at a measurement location. They are not interchangeable merely because both may be expressed in decibels. Ask the report owner to identify the quantity, reference, frequency weighting and any averaging or other reported metric, rather than relabelling an unexplained figure.
The public abstract for ISO 3744:2025 describes a method for determining sound power from sound-pressure measurements over a defined surface under specified acoustic conditions. Referencing that abstract does not establish that any Xiaochong model has been tested to this standard. The chosen method and its suitability belong in the agreed test scope.
For a reported sound-pressure result, ask where the measurement positions were and how the surroundings and background sound were addressed. Do not convert a catalogue number into a predicted bedroom or property-boundary level using an improvised distance rule.
3. Make each quotation answer the same evidence request
Use the following original register to expose gaps. These are proposed procurement fields, not a claim that every supplier already has every report.
| Evidence field | Question to resolve |
|---|---|
| Product identity | Which model, cabinet configuration, installed modules, cooling arrangement and relevant software/control revision were tested? What links that sample to the quoted unit? |
| Reported quantity | Is the result sound power or sound pressure? What weighting, units, metric and uncertainty information accompany it? |
| Operating condition | What output, active outlets and cooling state were recorded? Was the sample idle, charging or transitioning between states? Which intended operating cases remain unrepresented? |
| Measurement context | What method, environment, positions or measurement surface, background treatment and equipment records support the result? |
| Report traceability | Who issued the report, when, under which identifier and revision? Are limitations and any claimed laboratory competence or accreditation scope verifiable? |
| Project applicability | Which conclusions can the site reviewer use, what remains uncertain, and who owns any additional test or assessment? |
Keep the original report reference beside the comparison field. Do not strip away qualifications to create a cleaner-looking bid table. If the configuration changes after quotation, ask whether the evidence remains applicable and record the supplier's answer.
4. Resolve an unequal comparison without choosing the smaller number
Consider a fictional tender: quotation A provides a sound-pressure statement at a named position while the charger is idle; quotation B provides a sound-power report during charging. This is an invented comparison, not a Xiaochong customer case. Ranking their headline values would mix both quantities and operating states.
Mark the rows “not directly comparable.” Ask each supplier to identify evidence for the agreed use case, and let the project's competent reviewer determine whether existing reports are adequate or additional measurement is needed. Record the cost, schedule and decision owner for any extra work before treating it as included.
The hot-climate procurement checklist covers another reason to identify operating conditions. An acoustic proposal should not quietly replace the project's required charging capability or thermal operating envelope with an unverified reduced-performance assumption.
5. Agree site verification and change responsibilities
Product evidence and site acceptance are separate deliverables. Ask the qualified local reviewer to define the assessment locations, operating scenarios, timing, background handling, applicable criteria and reporting method for the actual project. Specify who commissions the work, who reviews results, and how an unresolved result affects handover. This guide supplies no universal pass/fail threshold.
Keep the acoustic review coordinated with the installation drawing release. Do not add a screen, enclosure or other modification, obstruct ventilation or service access, or disable cooling equipment as an improvised noise remedy. Any proposed change needs manufacturer input and the responsible designers' review before implementation.
Record the accepted configuration and approved changes in the handover package. Connect the evidence to the factory/site acceptance checklist, while keeping additional acoustic work explicitly scoped. A general FAT record does not automatically contain acoustic measurements.
6. Keep AC and DC SKD evidence separate
AC EV charger SKD kits and technical documentation: agree the AC model, supplied components, locally completed assembly and applicable document revisions. Identify whether relevant acoustic information is available for the final configuration; do not assume that evidence for a component describes the completed unit or site.
DC EV charger SKD kits and technical documentation: agree the DC module/cabinet configuration, cooling and control scope, integration documents and responsibility for final-unit testing. If a local partner changes the completed arrangement, have the evidence owner confirm which previous results remain applicable.
Xiaochong recruits overseas businesses interested in local charger production/assembly, SKD components, production/assembly technical support and repair/maintenance technical support. Available AC or DC technical documents are free on request. This does not make hardware, unrestricted source code, all intellectual property, certification, training, repair labour, exclusive territory rights or every project deliverable free. Models, components, document revisions, licensing and training/testing/support scope must be agreed for the project.
Buyer questions
Can two charger quotations be compared using only a dB value?
No. First identify the acoustic quantity, weighting, operating condition, measurement method and positions, and the exact product configuration. Treat missing information as an unresolved comparison, not as evidence that one charger is quieter.
Does a laboratory acoustic report approve my proposed site?
No. A product report does not establish the result at a particular neighbour, room or site boundary. A qualified local reviewer must assess the site and applicable requirements, then agree a suitable verification plan.
Is an acoustic test report included with free AC or DC technical documents?
Not automatically. Request the available documents for the selected AC or DC model and agree whether any acoustic report exists, what configuration it covers, and whether additional testing or professional services require a separate scope and charge.
Primary sources reviewed 6 October 2026: HSE purchasing guidance and the public ISO 3744:2025 abstract. The evidence register and tender example are original procurement guidance. No paid standard text or private technical file is reproduced.
Request model-specific AC or DC technical information
Send your company, country, AC or DC track, proposed model, number of units, intended operating pattern and the site reviewer's evidence questions. Request free available AC or DC technical documents and clarification of existing acoustic evidence. Any new testing, specialist assessment or additional deliverable needs its own agreed scope; only owner-approved documents may be shared.
Use the official partner programme, AC/DC SKD technical-output page and procurement guide to define the cooperation track. The free RFQ brief builder can organise the request; it is not an acoustic prediction or regulatory approval tool.
xc0225888@163.com · Sales 1: +86 137 1772 6888 · Sales 2: +86 134 2580 6997