EV High Voltage Harness | 800 V Battery Packs

Q: What is the prototype quantity?

For prototypes the floor is 5 pcs and lead time is 3 working days. Production orders begin at 500 pcs and ship 14 working days after sample sign-off.

Overview

An 800 volt traction pack is not a 400 volt pack with a different label on it. Moving the system voltage up changes what the insulation has to withstand, how the screen has to be terminated, and how much attention the distance between a live part and the vehicle structure deserves. An EV high voltage harness built for that has to treat insulation coordination, screen termination and the interlock loop as one design problem rather than three separate ones. The working-stress arithmetic behind a real voltage rating — and why dielectric strength is the wrong number to design against — is set out in our Kapton vs PTFE vs FEP vs silicone comparison. We build each path, meaning pack internal, pack to junction box, inlet to contactor and the interlock loop, as its own assembly so that one damaged leg can be replaced without re-looming the vehicle.

Key Specifications

Build Type	Build to print or build to sample
Conductor Size	Per your drawing; 32 to 12 AWG standard, larger power cores to order
Insulation	XLPE or silicone, temperature class per your drawing
Voltage Class	800 V class system, or otherwise as stated on your drawing
Current	Per leg, as stated on your specification
Screening	Foil and braid with the drain termination defined on the drawing
Interlock	HVIL loop routed as a separate circuit
Identification	Orange high voltage jacket, labels at both ends
Workmanship	IPC/WHMA-A-620 criteria, class per drawing
Testing	Continuity, dielectric withstand, crimp pull test

Insulation coordination: what we control

The insulation requirement for a traction system comes out of the coordination study your engineering team performs for the vehicle: working voltage, overvoltage category, pollution degree, and the clearance and creepage distances that follow from them. Those figures belong to your design and go on the drawing. What we control is everything a harness builder can get wrong. In an electric vehicle pack the usual offenders are a strip length that leaves too much bare conductor at a terminal, a crimp that lets strands escape toward a neighboring pole, a marker sleeve placed where it bridges two points, and a bend radius tight enough to push a live terminal against the enclosure. Each of those is checked on the drawing and on the part.

Ask three suppliers how to end a screen and you will get four answers. These are the options, with the trade-off stated plainly:

Method	What it gives you	What it costs	When we would use it
360 degree termination to the connector shell	The screen continues through the interface with no break	Needs a connector and backshell designed for it	The default for high current legs running beside low voltage looms
Foil plus braid with a short drain	Good coverage and a simple build	The drain becomes the weak point if it is left long	Where the connector does not support a full circumferential interface
Screen bonded at one end only	Avoids a ground loop between two boxes	Needs the decision stated on the drawing, not left to the line	Where your electromagnetic compatibility plan calls for it explicitly
Overall screen over the whole loom	One treatment for a mixed loom	Can hide a leg that needed its own screen	Where the drawing accepts a single treatment

The third row is the one that needs a decision rather than a default. Whether a screen is bonded at one end or both is an electromagnetic compatibility choice that belongs to the vehicle, not to the harness.

The interlock loop

The high voltage interlock loop tells the vehicle that a service plug has been removed or a cover has been opened, and it only does that job while it is independent. We route it as its own circuit with its own connector positions rather than splicing it into a power leg, and we make sure it opens first and closes last in the mating sequence so the controller sees the break before anything else can happen. Series or parallel is your call and goes on the drawing.

Identification and workmanship

Orange outer jacket is the conventional high voltage identification in traction battery practice, and every leg is labeled at both ends. The loom is built to IPC/WHMA-A-620 workmanship criteria with the class specified on your drawing. We do not hold ourselves out as holding a certification your program has not audited: we build to the criteria you name and document what we did, including crimp tooling settings and pull test results, so your process file has evidence rather than an assertion.

Typical applications for this EV high voltage harness

Module to module and module to junction box links inside the pack
Pack to high voltage junction box, and pack to onboard charger runs
Charge inlet to contactor assemblies
Interlock loop looms built as their own part number
Prototype and pre-production looms built to the same drawing as production

Testing

Continuity and polarity on every power and interlock circuit
Dielectric withstand test at the voltage stated on the drawing
Crimp pull test on first-piece and sampled production parts
Screen continuity and insulation resistance recorded per serial number

Custom builds and ordering

EV High Voltage Harness builds are assembled and inspected to IPC/WHMA-A-620 Class 3 criteria, with ISO 9001 as the quality system over 32 to 12 AWG work. continuity and pinout are checked on every EV unit before packing, and seal checking is quoted whenever an ingress rating is on the drawing.

RoHS and REACH declarations are provided per project together with the agreed test reports; the documentation scope is listed under certifications and compliance. If your drawing specifies a UL style, we build to that drawing and supply the UL reference with the shipment instead of substituting an equivalent. Injection parameters for this part are developed against the jacket material using the approach documented under overmold materials and injection parameters. Related reading: prototypes and first article inspection. Any tooling we cut for this part stays yours, maintained in our own tool room under your part reference.

EV High Voltage Harness prototype builds start from 1 to 50 pcs and are out in 3 working days. Production is quoted from 500 pcs at 14 working days after approval. Tooling not already held adds around 10 working days. Private-label EV runs ship under your part number and labeling, and material certificates and first-article reports come with them on request.

Frequently Asked Questions

Do you build the interlock loop into the power harness?

We can, but we advise against it. Routing it as a separate circuit with its own connector positions keeps it independent of the condition of the power conductors.

How do you terminate the screen?

To the method on your drawing. Where the connector supports it we use a 360 degree interface; where it does not, we use a short drain and record the length on the build record.

Can you build from a sample from an earlier build stage?

Yes, and it is often the fastest route to an accurate quote. Send the sample with the connector part numbers and the current per leg.

What is the prototype quantity?

EV High Voltage Harness prototype builds start from 1 to 50 pcs and are out in 3 working days. Production is quoted from 500 pcs at 14 working days after sample sign-off.