Electric Vehicles & Charging Infrastructure
On the vehicle side — HV junction box, cable terminations; on the infrastructure side — MCS 1500 A. One bimetal material for both.
The problem you need to solve
Two points in electric drivetrains cannot avoid the Al/Cu encounter. On the vehicle side: connecting the HV battery (Al laminate construction) to the traction inverter and OBC (Cu busbars) via the HV junction box, where every phase terminates in a bolted Al/Cu joint. The environment is –40 → +85 °C (UN ECE R100 Rev. 3), vibration, and 10 years continuous operation. On the infrastructure side: the CCS (250 A DC) and especially megawatt charging (MCS, 1500 A DC, IEC TS 61851-23-3 / SAE J3271) connector internal cable lugs see a Cu terminal pin meeting an Al conductor — even in liquid-cooled cables. Both points share long lifetime requirements (OEM: 10+ year warranty; public charger: 15+ years), zero-maintenance expectation.
In short
In electric vehicles and charging infrastructure, aluminium and copper conductors meet in the on-board HV junction box and the CCS/MCS connectors; the CUPAL bimetal transition solves this Al/Cu joint paste-free — saving weight on the vehicle side, holding contact through the IEC 61851 and IEC 62196 thermal cycles.
- 400 → 1000V DC
- Typical HV voltage range
- 1500A
- MCS peak current (SAE J3271)
- –40 / +85°C
- UN ECE R100 thermal cycle
- ~49%
- Weight saving vs. pure Cu
How CUPAL solves it
CUPAL provides a solution from a single material for both vehicle and charging infrastructure sides. For the vehicle: transition between the HV junction box Al body and Cu bus, cable lug washer at the battery or inverter terminal. On the weight side: the same cross-section in pure copper would be ~49% heavier (Al/Cu density ratio); CUPAL's Cu layer is only 30% — every gram matters in the vehicle. On the connector side: the Al/Cu transition of the CCS/MCS connector internal cable lug can be sealed paste-free with a CUPAL washer; the connection passes IEC 61851 and IEC 62196 thermal and mechanical cycles with unchanged contact. The base material comes with material certificates required for UN ECE R100 and ISO 6469-3 electrical safety tests.
EV-specific parameters
Where it's used — in the vehicle and the charger
Four specific points — two on the vehicle side, two in the infrastructure.
On-board HV junction box: battery Al body → Cu bus
The problem you need to solve. The battery pack is aluminium, the outgoing inverter busbar is copper. The HV junction box carries current across Al/Cu bolted joints. Continuous vibration + thermal cycling creeps the contact.
How CUPAL solves it. CUPAL transition washer or sheet at every HV junction box Al/Cu bolted joint. Al side towards the pack, Cu side towards the bus; the bimetal material seals the interface internally — no paste in the vehicle.
Motor controller connection: inverter Cu → motor winding
The problem you need to solve. The traction inverter starts from Cu busbars; in some systems an Al intermediate conductor is used for weight savings. Every Al/Cu joint deteriorates under thermal loads over 10 years.
How CUPAL solves it. CUPAL shim a few mm thick at the bolted joints. The HV system electrical safety (ISO 6469-3) can be directly tied to a tested component.
CCS charging cable connector interior
The problem you need to solve. Inside the CCS connector housing, there is a cable-lug-type bolted joint between the liquid-cooled Cu terminal pin and the external Al conductor. 250 A DC continuous + fretting from regular plug/unplug cycles.
How CUPAL solves it. CUPAL washer between the pin and the conductor. Paste-free, does not degrade thermal behaviour per IEC 62196-3, Al oxide cannot grow inside the bimetal interface.
Bus depot / fleet MCS charging point
The problem you need to solve. Fleet-site MCS charger (1–3 MW) draws current from multiple output cabinets; the MW-level Al busbar converges onto Cu breakers. Continuous 16–24 hour/day operation, downtime unacceptable.
How CUPAL solves it. Custom CUPAL transition segment between Al bus and Cu breaker terminal. Cut to site-specific geometry, for busbar systems per IEC 61439-7 charging station standard.
Compared to alternatives
EV decision matrix — weight on the vehicle side, service life on the infrastructure side.
| Solution | Contact over 10+ years | Maintenance | Lead time | Lifetime cost / joint |
|---|---|---|---|---|
| Bolted Al/Cu + paste | Drifts, fretting present | Annual service on public charger | From stock | High (public charger: on-site downtime) |
| Special Al/Cu connector (OEM custom) | Stable | None | OEM program, long | High (OEM proprietary) |
| Pure Cu (Al-free design) | Stable | None | Standard | High (vehicle weight + Cu price) |
| CUPAL custom cut | Stable | None | 2–4 weeks | Low, with weight saving |
Common questions from OEM and charger manufacturer engineers
Recommended CUPAL products
Applicable standards for this field
Knowledge Base — CUPAL Technical Resources
3/1/2026
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Read the full article →2/15/2026
What is CUPAL?
CUPAL is a cold-roll-bonded, diffusion-welded copper-aluminum bimetal composite. Learn its composition, manufacturing process and properties.
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