How do you take an EV product from concept to a prototype?
Write the question before you order the board. A fair question is whether the connector can be mated where a hand can reach, whether the circuit still behaves when the supply sags as you assumed, or whether the enclosure and the cables can be assembled without a workaround you will forget. EV product design treats those as one product, not as a schematic plus a housing. Which stage may answer which question is set out in Hardware Product Development Process Explained. The sums below are invented teaching arithmetic. They are not a BrahmWorks measurement, price, yield, timeline or test result.
A kitchen planter with a grow light
Freeze the boundary before the shape
A concept that says "an EV module" has not started. Name the domain you may touch, and the acts you may not perform: torque, contactors, charge current, restraints. Say that in the concept and on the prototype. A visitor who sees a box in a vehicle will assume the box is doing more than it is.
Name the domain you may touch, and the acts you may not perform: torque, contactors, charge current, restraints.
Freeze the interface you do not own. Connector, return, mounting points and the thermal neighbour are usually someone else's parts. A build that invents a convenient connector, then "will adapt later", has tested the convenient connector. Record the revision you mated to. "A vehicle supply" is not a revision.
Write what this build omits, and the conclusion that omission forbids. A printed shell may stand in for reach and clash if you do not call it the production material. A bench supply may stand in for a logic boot if you do not file that boot as evidence about noise or a voltage that moves when a contactor operates. An omission without a forbidden conclusion will be quoted later as if the test had covered it.
What the vehicle adds
The return path is a mechanical part. A long or shared wire, or a ring terminal under a screw that also holds a panel, will not behave like the short lead on a laboratory supply. Use the return you mean to ship, or say that return impedance is untested. A connector that is easy on a bench becomes a fatigue problem when the harness moves with a panel, or when someone uses the plug as a handle. Retention, bend relief and a service loop belong in the prototype if the product will be unplugged in the field.
Heat leaves through parts. A board in open air is not the same product as a board against a metal wall, under a display or beside a cable bundle. If the enclosure is the sink, the build has to include the interface, the contact pressure and the neighbours that also make heat. Service access is part of the same review: fuse, latch, programming header and terminals, in the order a technician meets them. Have someone other than the designer assemble it once. Record which supply, harness, firmware and mechanical revision were together when it passed or failed.
What a running board does not show
A render is not a prototype. A current copied from a catalogue, without the mating cycle and the wire you will use, is not a measurement. An installation that depended on a tie-wrap the work instruction does not mention is a workaround. If the only unit that works is the one the designer assembled, you have learned about that person.
Compliance is not a by-product of a board that ran. Identify electrical safety, electromagnetic behaviour and the vehicle interface as their own scope, with someone qualified to name them for the markets you mean. A bring-up is not a clearance. If the honest build would be unsafe to energise in the configuration you care about, narrow the question until it is safe, or do not run it. Calling the build a concept does not remove a hazard you have already created.
Worked example: a protected accessory outlet
The teaching product takes an existing low-voltage feed and provides a fused outlet for accessories the vehicle maker did not fit. It does not control propulsion, charging or restraints. It is not a BrahmWorks project and not a tested product. The question is whether a technician can mate the connector and replace the fuse on the intended mounting face, and whether the board leaves reset when the supply is sagged to the minimum written down.
In the build: the connector family you intend to keep, a reachable fuse, the harness return, and a supply you can pull down while you watch reset. Out of the build: a tooled housing, a named platform, and any unit that is then driven. A printed bracket may reproduce the face and the hand clearance. It is not the production part. The note forbids electromagnetic claims, vibration life and any other connector. If the fuse cannot be reached, the question has been answered and the layout has failed.
Labelled calculation: heat in one contact
These figures are assumed so the arithmetic can be checked. They were not measured on a BrahmWorks product, a vehicle or a supplier part.
Assume one mated contact is 0.8 milliohm and the current is 25 amperes. Power is current squared times resistance. 25 squared is 625. 625 times 0.0008 ohm is 0.5 watt in that contact. A second contact at the same assumption makes 1.0 watt, before wire, fuse and copper.
At 0.2 milliohm, the sort of "typical" line copied from a different contact, power is 625 times 0.0002, which is 0.125 watt. The assumptions differ by four. The build has not chosen between them unless the real contact, the real wire and a real mating were measured. Crocodile clips delete the term. Do not turn 0.5 watt into a temperature rise. Rise depends on the metal, the air and the neighbours, which this sum does not contain. If you need a rise, measure the configuration you mean to ship, and keep that record apart from this teaching sum.
What each build can support
The middle row is often the right prototype. Teams skip it because the packaged unit looks more like a product in a photograph. The photograph is not the question.
Checklist before you call it a prototype
- The job, the electrical boundary and the acts the product must not perform are written.
- Connector, return and mounting face are identified by revision, or the omission and the forbidden conclusion are written.
- The supply assumption is something you can impose on the bench.
- Heat, strain and service access are in this build or explicitly untested.
- A second person has assembled the unit, and the stops are recorded.
- Workarounds are logged as design changes, instructions or open items.
- Safety and vehicle-interface requirements are a separate scope, not inferred from a board that ran.
- This configuration is distinguished from any later vehicle installation.
Related questions
Does the prototype have to be fitted to a vehicle?
Only if the question cannot be asked anywhere else. Face, hand clearance and a supply you can sag can be reproduced on a bench. Behaviour in a particular body, or on a harness you do not control, usually cannot. A trial fit is still a trial configuration. Do not drive or charge a system the prototype is not qualified to touch.
When should the safety scope be opened?
As soon as you know the energy and who can touch the product, including a technician with the cover off. Opening that scope is not booking a laboratory for a unit you expect to respin. The sample has to be the configuration you mean to submit.
Is a development board an EV prototype?
It is a prototype of the logic only, and only if the result says so. Once the product has a connector, a fuse and a place in a vehicle, a bare board is an incomplete question. Bring those parts in when they can change the answer.
What should the concept refuse to promise?
Refuse range, charge time, platform approval and any reliability percentage. None of those live in a concept, and a vehicle brochure describes someone else's vehicle. Promise the job, the boundary and the next question.
Review the boundary before the enclosure gets handsome
Bring the job sentence, the interface you do not own, and the conclusion this build must not support. BrahmWorks can say whether the next prototype is still that question, or whether you are about to pay for a shape that freezes the wrong connector.