A buyer searching for OBC is usually trying to stop a bad substitute. EV charging hardware is specified by power, the connector, the supply, and who may install it. The notes below are selection criteria for an OBC. They are not a catalog promise. Confirm every rating on the current datasheet, drawing, or test report for the revision you will receive.
What has to be true of OBC
EV charging hardware is specified by power, the connector, the supply, and who may install it. For an OBC, start from the duty, then the interface to the rest of the machine or the room, then the document that proves the claim. A lower price that leaves one of those blank is a different product.
OBC is easy to confuse with Hub Motor. If the quote could be read as either, add the line that separates them: the rating, the fitment, or the standard named below. Link the drawing number to that line so receiving inspection can reject the wrong one.
Numbers that change the quote
| Line | What to write for OBC |
|---|---|
| Declaration | The charging-equipment declaration for the market. |
| Power | Kilowatts, single or three phase, and the supply available on site. |
| Connector | Type 2, CCS, CHAdeMO, or the adapter, matched to the vehicles. |
| Installation | Wall, pedestal, or portable, and indoor or outdoor IP code. |
| Protection | Residual current and overcurrent as the local electrical rules require. |
| Network | Whether billing or load management needs a back office. |
How to compare two offers
Lay both quotes for OBC on one sheet and line up declaration, power, and connector. If a cell is empty, the offer is not finished. Ask for the missing line in writing. When those match, the honest difference is lead time, the test evidence, and who carries the warranty. Do not average a fully specified OBC with a cheaper line that omitted declaration.
Documents worth having before the deposit
The conductive-charging series IEC 61851 is the usual reference. Confirm the part of it cited on the declaration. The file should name OBC and the revision, not only the supplier’s homepage. A factory quality certificate such as ISO 9001 can sit beside that file. It does not replace it.
Failures that show up after delivery
- Buying a connector the fleet does not have.
- Ignoring the building supply and expecting the nameplate kilowatts.
- Leaving residual-current protection to be invented on site.
On an OBC, the expensive version of the first mistake is discovering it after the goods are in the crate. Put the rejection condition in the purchase order while the supplier can still restate the offer.
A worked RFQ line
Use this shape, then replace the brackets with your duty: “OBC — State kilowatts, phases, connector, IP code, and the supply.” That sentence is a template, not a rating of any brand. If a supplier’s datasheet uses different units, convert them onto this sheet so the next offer can be compared.
Where words like automotive grade belong
Searches often add a constraint to OBC: automotive grade, or stainless / corrosion. Keep those on this page. Automotive grade is a temperature, vibration, and documentation claim. Ask which AEC or customer spec is actually met, and for which part number. Name the alloy or the coating and the chemical it must survive. Stainless is a family, not a guarantee. If you need a third constraint, add it as another line on the same drawing. A second URL that only swaps the adjective does not give a buyer a second fact.
Related in this section: how to specify Hub Motor.
Questions buyers actually ask
What should an RFQ for OBC include?
State kilowatts, phases, connector, IP code, and the supply.
Is a cheaper OBC the same part?
Only if declaration, power, and the documents match. A missing line is a different offer.
Do waterproof, OEM, or IP words need their own page?
No. For OBC they are extra lines on this specification. Ask for the test or the drawing that gives the word a value.