A battery pack harness is bought as a performance requirement, not a drawing. What the RFQ has to lock down, and where the schedule actually goes.
Battery pack harnesses go wrong in sourcing for one reason more often than any other: the RFQ is written like a harness RFQ. A conventional harness can be bought from a drawing, and the drawing settles almost everything. A pack harness is bought as a performance requirement — the customer states the voltage, the current, the temperature range, the shielding and the environment, and the construction is the supplier's to propose. If the RFQ carries a drawing and nothing else, the supplier fills the gaps with assumptions, and the assumptions are where the cost and the schedule risk sit.
This is what to put in the RFQ, what the supplier should have to prove, and where the calendar actually goes between enquiry and production.
| Item | Why it has to be decided up front | Common range |
|---|---|---|
| Rated voltage and continuous current | Sets the conductor cross-section and the insulation wall. It also decides whether a shielded construction is mandatory or optional. | 300 V, 600 V or 1000 V DC |
| Operating temperature range | Drives the insulation material and the terminal plating. A range quoted at the ambient temperature rather than at the conductor is the most common RFQ error. | −40 ℃ to +125 ℃ |
| Conductor and insulation | The selection is a three-way trade between temperature, flexibility and cost, not a preference. | Tinned or bare copper; PVC, XLPE or silicone |
| Shielding requirement | Decides the construction and the terminating method at both ends. Retrofitting shielding after the first article is a new part, not a change. | Braid, foil, or braid over foil |
| Connector interface | Housing, terminal and seal are three separate part numbers, and each one has a lead time of its own. | TE, Molex, JST, Amphenol, Deutsch — or customer-specified |
| Sealing and ingress protection | Decides whether the assembly carries seals, boots or overmoulds, and therefore whether a leak test is a line requirement. | IP67 or IP68 where specified |
| Flex and routing constraint | A pack harness is often dressed into a channel with a fixed bend radius. If the minimum radius is not stated, the first article will not fit. | Minimum bend radius and cycle count |
| Reference standards | Says which test regime the supplier is expected to work to, so the first-article report is not a surprise. | ISO 6722, LV214, or customer-specified |
| Volume, and whether it is firm | Decides how much tooling is amortised and which process the part is routed through. | Annual volume, firm or forecast |
The two rows buyers most often leave blank are the bend radius and the temperature definition. Both are cheap to state and expensive to discover later — the first because a harness that does not dress into the channel is scrap, and the second because a 125 ℃ requirement measured at the conductor is a different material from one measured at ambient.
The same physical cable can be three different products depending on where it sits in the vehicle or the rack, and buying the wrong one costs a requalification:
Ask for the quality management certificate and read the scope, not the title. Our manufacturing runs under IATF 16949:2016 (certificate 0597346) and ISO 9001:2015 (registration CACQ22Q00816R1), and the IATF scope covers manufacturing of wire harness while excluding product design under Clause 8.3 — which matters here more than on a conventional harness, because on a pack assembly the supplier is often the one proposing the construction.
Beyond the management system, workmanship and product compliance are governed by whatever standard your programme mandates. Ask the supplier to state plainly which workmanship standard they build to, rather than to list every mark they have ever been asked about. A supplier who responds with a long list of marks they do not currently hold is telling you they answered the question they wished you had asked.
What you should be able to get as evidence, in any case:
| Stage | Typical duration | What drives it |
|---|---|---|
| DFM feedback on the requirement | A few working days | How complete the RFQ is. A loose RFQ costs a round trip, not a week. |
| Connector and material procurement | The variable that catches people out | Whether the connector is a stocked catalogue part or a long-lead automotive-grade item. |
| Sampling | 5 to 10 days | Whether tooling or a forming board is needed. Sealed and overmoulded parts sit at the long end. |
| First article and approval | Your own review time | Whether the report has to be circulated to a customer of your own. |
| Mass production | 2 to 4 weeks | Volume, and whether the material is already on the floor. |
Sampling and mass production are quoted per project rather than as a fixed number, because the connector lead time is outside anyone's control and a firm promise on it would be a guess. What a supplier should give you instead is the two figures separately — sample and production — with the connector procurement named as the item that can move.
A pack harness programme is usually awarded after some form of supplier verification, and that can be done remotely if it is structured. Four things to ask for, in this order:
If a supplier cannot do all four, the question is not whether they are hiding something — it is whether the information exists in a retrievable form at all, which is itself the answer.
You can, and it is often the right choice for the assembly that runs from the pack to the rest of the vehicle, where the routing and the connector positions are fixed. Inside the pack it is usually the wrong instrument, because a drawing that fixes the construction also fixes the responsibility for it — if the harness later fails a temperature or shielding requirement, the drawing is where the discussion starts and ends. A performance requirement lets the supplier propose a construction and own the outcome, which is what you are paying for on a high-voltage part.
Plan the sampling stage at five to ten days and mass production at two to four weeks, and then add the connector procurement time on top rather than assuming it is included. The connector is the item that most often moves the date, and it moves for both sides — a long-lead automotive-grade housing ordered in week one is a two-week delay that no amount of production efficiency recovers. Ask specifically whether the connector in your design is a stocked part or a lead-time item, and get the answer in writing before the PO.
Ask for the standard by name and then ask for the evidence that refers to it: a first-article report whose acceptance criteria cite the specification, a work instruction on the line that quotes the limit, and a test record with the limits applied. A supplier building to a named standard can produce all three without preparation. Ask also how deviations are handled — on a drawing-driven part they are quoted as a separate line, and the same discipline should apply to a performance specification, where a proposed alternative should come with the reasoning attached rather than appearing in the finished part.
Guides & Insights · Sep 24, 2026Price tells you what a supplier charges. These nine checks tell you whether the part will still match the drawing on the tenth shipment.
Learn more
Guides & Insights · Sep 23, 2026Both standards are quality management systems. Only one of them is written for automotive production parts — and the certificate scope decides more than the title.
Learn more
Guides & Insights · Sep 21, 2026A harness is a system of conductors, terminations and protection bundled into one assembly. That definition decides how it is bought, built and tested.
Learn moreA drawing, a sample, a connector list or a photo is enough to start. Typical reply within one working day, with engineering questions rather than a sales pitch.
