EV platforms live at the intersection of high voltage, high power and strict safety requirements. From battery packs and traction inverters to DC fast chargers and cable harnesses, engineers must prove that insulation is sound during development and at end-of-line. That is the role of high-potential testing. In a withstand test the product is stressed above normal operating voltage and leakage is measured. In a breakdown test the voltage is increased until insulation fails so that safe design margins can be set. Both require precise control of kilovolt sources, very low leakage measurement and safe discharge paths.

This article shows how to build reliable hipot stages for EV testing and why high-voltage reed relays are a strong fit for the switching and safety functions inside those stages.

Where hipot fits in the EV lifecycle

Battery modules and packs
Verify isolation from chassis, check coolant ingress risk, validate contactor assemblies and pre-charge networks. End-of-line stations typically perform DC withstand tests and store leakage results as a baseline for field service.

Traction inverters and DC-link assemblies
Validate the isolation barrier between the high-energy DC bus and control electronics, then repeat after thermal cycling or vibration stress.

Onboard chargers and DC fast chargers
Confirm isolation from the AC grid and between power stages. For megawatt-class systems, safe discharge after a test step is essential before operators can connect the next unit under test.

High-voltage wiring harnesses and connectors
Cable hipot checks for pin-to-pin shorts and pin-to-shield leakage, often across hundreds of nets through a switching matrix.

These use cases push the same core requirements on the hipot station: apply and measure at kilovolt levels, limit fault energy, sequence tests safely, minimise test time, and keep leakage measurement trustworthy.

Why the switch technology matters

Inside most hipot rigs you will find a programmable HV source, measurement and protection hardware, and a bank of switches that route the source and meter to the unit under test or to a discharge load. The switches shoulder several jobs at once. They must:

• withstand high open-circuit voltage without breaking down
• switch the desired voltage and energy when required
• contribute little leakage or parasitic capacitance
• isolate control electronics from the HV domain
• operate quickly and repeatably over long duty cycles

Electromechanical relays are affordable but their open-air contacts limit practical switching voltage and standoff. Solid-state relays are fast and compact, yet introduce non-linear leakage and higher off-state capacitance that can mask real leakage in the device under test. High-voltage reed relays solve a different set of problems. The contacts are sealed in an inert vacuum, so they tolerate higher electric fields in a small package and deliver extremely low off-state leakage with very low parasitics. The coil is galvanically isolated from the signal path, which protects control electronics. Operate times are short, typically under a millisecond, which helps keep cycle time down.

In short, the switch behaves more like a near-ideal open or closed conductor, which is exactly what you want when measuring microamp or nanoamp leakage.

This graph shows a comparative plot of leakage current versus isolation voltage for several switch classes. Traditional EMRs rise early and are limited by their lower standoff. Typical high-voltage SSRs hold longer but still leak in the microamp region as voltage climbs. Instrument-grade reed relays maintain much lower leakage at higher voltages because insulation resistance is orders of magnitude higher, into the 10¹² to 10¹³ ohm range for standard devices and up to 10¹⁴ ohm in custom builds. For battery, inverter and charger hipot, that difference is the gap between a clean pass and a false failure.

Architecting a hipot stage with reed relays

A practical EV hipot station will include several relay-controlled paths:

1. Source routing. Select the desired voltage domain, for example pack positive to chassis, pack negative to chassis, or pin-to-pin on a harness. Reed relays with high standoff ratings serve as the isolation elements here.
2. Measure path. Switch the meter across the device under test or to a reference load for self-check. Low leakage and low capacitance in the relay help preserve measurement fidelity.
3. Discharge and bleed. After a test step, route a resistor across the output so stored energy is removed before the operator proceeds. Using a dedicated reed relay for this function creates a predictable, safe discharge path every time.
4. Protection and interlock. Separate relays can enforce permissives, for example open the source path instantly if limit current is exceeded and latch the system until the discharge completes.

Because reed relays are compact and magnetically screened, many channels can be packed on a single board to build scalable harness or pack fixtures. If you need Kelvin measurements elsewhere in the station, two-pole devices reduce the channel count for four-wire connections.

Picking the right device: what to look for

When you choose relays for hipot switching, match the specification to the job:

• Minimum standoff voltage. This is your open-contact survival number. For EV and charger work, devices with 5 kV, 10 kV or 20 kV ratings give comfortable headroom.
• Maximum switching voltage and power. For breakdown tests and for controlled discharge, ensure the relay can switch the intended voltage and energy without contact erosion.
• Switch-to-coil isolation. Protects your controller if the HV path faults. Our customizable Series 600 can be configured for up to 25 kV switch-to-coil isolation.
• Insulation resistance. Higher is better for leakage fidelity. Standard Pickering HV relays are tested to greater than 10¹² ohm, and custom parts can reach greater than 10¹⁴ ohm.
• Operate and release times. Faster operate reduces dwell, faster release shortens the discharge-to-ready interval.
• Physical format and shielding. Internal mu-metal shields allow side-by-side packing with minimal magnetic interaction, which matters when you scale to large matrices.

Product options that map cleanly to EV hipot

You can build most EV hipot matrices from a small set of families:

• Series 63 and the customizable Series 600, for the highest isolation demands. Up to 20 kV standoff with switching up to 12.5 kV, 200 W max. Series 600 adds modular options for voltage, coil, shielding and mounting, and can be configured for up to 25 kV switch-to-coil isolation. Both series also include changeover options up to 2.5kV switching and 5kV standoff. Good fits include pack and charger isolation tests, inverter barrier validation and long-duration burn-in where standoff margin helps.
• Series 60 and 65, for high-voltage routing where space is tight. Up to 12.5 kV switching and up to 15 kV standoff, with switch currents up to 3 A at 50 W and carry currents up to 3.5 A. Often used in cable and harness hipot fixtures.
• Series 104, compact devices with 5 kV standoff and 1.5 kV switching. Useful as measurement selectors, discharge path control, or safety interlocks inside the rig.
• Series 67 and 68, high-power options that bring 200 W switching into a dense package with up to 10 kV standoff and 7.5 kV switching. Helpful where you need higher current discharge networks or stress steps. They also have a unique design to enable higher density packing, whilst still maintaining appropriate distances between pins. Changeover options are also available up to 2.5kV switching and 5kV standoff.
• Series 119 and surface-mount Series 219, for compact boards that still need up to 3 kV standoff and 1 kV switching. These enable dense multi-channel fixtures that slide into modular testers.

If your topology calls for two-pole parts, we also offer a wide range of 2-pole configurations to support Kelvin connections and reduce channel count.

Design tips that save time on the bench

• Think in energy, not only voltage. A 5 kV breakdown step into a capacitive load stores energy that must be discharged safely. Rate the discharge relay and resistor for both voltage and pulse energy.
• Guard your measurements. Use guarded layouts and high-resistance materials around the relay pins so leakage paths do not bypass your meter. Internal shields avoid the external clearances that can limit open-contact voltage in some designs.
• Sequence for operator safety. Interlock the source path with the discharge path and door switches. Use the relay’s fast operate and release times to shorten the safe-to-touch interval between DUTs.
• Validate at temperature. Leakage and standoff are temperature sensitive in many systems. Run a short design validation that sweeps temperature with your chosen relay set before freezing the BOM.

Closing the loop with production needs

EV programs live on throughput. Cycle time and uptime matter as much as headline voltage. Reed relays help on both fronts. Operate times can be sub-millisecond, so routing steps do not dominate the test. Mechanical life extends to millions or even billions of operations when used within rating, which keeps fixtures in service and reduces maintenance. Low coil power also helps thermal design in dense racks.

For engineers who need to standardize across platforms, the same relay families show up in pack hipot, charger isolation, inverter barrier checks and cable harness testers. That simplifies spares and documentation and lets you reuse known-good layouts.

Where to start

If you are building or refreshing an EV hipot station, a practical selection is one of the Series 63 or Series 600 devices for the main isolation paths, Series 104 for measurement and interlocks, and Series 67 or 68 for discharge control when higher power is required. For compact harness fixtures, look at Series 119 or 219 to keep density high. If you have a constraint that a catalog device does not meet, our engineering team can tune coil voltage, shielding, pinout and isolation to match your design rules.

Have questions or want to review a schematic? Our expert reed relay engineers are happy to help select parts, discuss creepage and clearance on your board, and advise on discharge sizing and safety interlocks for your voltage and energy levels.

Turntide Technologies has expanded its axial flux motor lineup with two new models. The AF300 delivers more than 192 Nm of continuous torque; the AF400 delivers up to 290 Nm. Both are available in single- and double-stacked configurations, giving OEMs a range of performance options in the same compact axial flux form factor.

The previously announced AF430S (single-stack) and AF430D (double-stack) are the first in the portfolio to gain cast casings, which Turntide says improve durability, consistency and production cost efficiency. The cast casing design is built for high-volume production. Turntide plans to extend cast casings across the full axial flux lineup.

Don’t miss Turntide’s webinar: Why axial flux motors are powering the hybrid shift
Register now. It’s free!
May 19, 2026 11:00 AM ET

Axial flux motors’ low-profile design allows installation in space-constrained platforms without platform redesign—the key pitch to OEMs and fleet operators looking to hybridize or electrify existing equipment. For diesel fleet operators, hybrid retrofits using these motors can reduce fuel consumption by 10% to 20%, depending on the application.

“Hybridization is gaining momentum because it delivers what we call a dual green effect,” said Steven Hornyak, CEO of Turntide. “It reduces fuel consumption and emissions while improving operating economics at the same time. Turntide’s axial flux motors make it possible to deliver hybrid systems where space and performance have typically been limiting factors.”

SEE ALSO: A closer look at axial flux motors

Source: Turntide Technologies

IONCHI, the premium high-power charging joint venture established by BMW and Mercedes-Benz in China in 2024, has announced that SERES Group will join as an equal shareholder. Through the investment, SERES’ premium brand AITO becomes part of the three-party network, giving BMW, Mercedes-Benz and SERES each a 33.3% stake. The transaction is subject to regulatory approval.

IONCHI operates public high-power charging stations at prime urban locations across China, powered by 100% renewable energy. The network offers premium services to all eligible EVs, with online reservation and priority power allocation reserved exclusively for customers of the three OEM brands.

AITO, SERES’ luxury EV line, has surpassed one million cumulative users and was the best-selling Chinese luxury car brand domestically in 2025. Adding SERES as an equal partner gives the network a third OEM driving geographic expansion, network density and service development alongside the two German brands.

Source: Seres Group

ROHM has developed its 5th Generation SiC MOSFETs under the EcoSiC brand, delivering approximately 30% lower ON resistance during high-temperature operation compared to its 4th Generation devices. The comparison is at Tj=175°C with equivalent breakdown voltage and chip size—meaning the reduction comes from structural enhancements and manufacturing process optimization, not geometry scaling.

Lower on-resistance at high operating temperatures matters directly to traction inverter design. SiC MOSFET on-resistance rises with temperature, and devices run hottest under peak load—exactly when losses are most critical. A 30% reduction at Tj=175°C means less conduction loss per switching cycle, which supports either smaller packaging or higher continuous output from the same chip area, or some combination of both.

Target applications include xEV traction inverters, OBCs, DC-DC converters and electric compressors. ROHM’s 4th Generation—which began sampling in June 2020—has been broadly adopted in automotive and industrial applications; the 5th Generation targets the same segments with improved high-temperature efficiency. ROHM says it began the world’s first mass production of SiC MOSFETs in 2010.

ROHM has been shipping 5th Generation bare dies since 2025 and completed full device development in March 2026. Discrete device and module samples are scheduled for July 2026, with additional breakdown voltage and package options planned.

Source: ROHM Semiconductor

Axens’ MACARON project, a planned cathode active materials (CAM) plant for EV batteries in Saint-Saulve, Northern France, has cleared three policy milestones in quick succession. The Élysée has designated it one of France’s 150 “major strategic projects,” the French State has awarded it a Net Zero label and it has received approval for a 25% investment tax credit under the Green Industry Investment Tax Credit (C3IV) scheme.

MACARON is designed to supply cathode active materials to the French and European EV battery supply chain. The project entered public consultation about a year ago.

The Net Zero label, awarded in March 2026, recognizes the project as strategic to “reduce Europe’s industrial dependency in the field of strategic battery materials” and “strengthen the resilience of the European electric vehicle value chain.” The designation is expected to bring closer attention from French and EU permitting authorities during the authorization process. The C3IV approval, received earlier in 2026, entitles the project to reimbursement of 25% of eligible plant construction and equipment installation costs—support Axens describes as “absolutely essential” to enabling the project.

Environmental authorization and building permit applications are due in the coming weeks, with a public inquiry scheduled for summer 2026. A final investment decision is targeted for mid-2027, with startup envisioned by 2030.

“This is an additional recognition of the strategic importance of locally producing advanced battery materials for French and European industrial sovereignty,” said Quentin Debuisschert, CEO of Axens.

Source: Axens

UK Energy Secretary Ed Miliband has revealed a package of new measures to accelerate the UK’s clean energy transition. The measures include steps to encourage deployment of solar energy and heat pumps, as well as “streamlining outdated rules to unblock the grid and speed up [deployment of] clean, homegrown power…cutting delays for essential grid upgrades.”

Speeding up the grid modernization process is a much-needed reform that will benefit the EV industry, but the measure that EVangelists are really excited about is a commitment to make it easier for drivers without driveways to gain access to EV charging at home.

“This summer, the government will legislate to introduce permitted development rights to expand EV charging provision, allowing for cross-pavement charging solutions and associated charging points,” the UK’s Department for Energy Security and Net Zero announced. “We will also shortly launch a consultation on changes to building regulations and wider plans to improve the ability to charge. This will look to increase EV charging provision in new buildings and those undergoing major renovations, as well as give renters and leaseholders greater access to charging by making it easier to request and install charge points.”

This news was especially welcome to UK charging providers that specialize in on-street charging.

“Today’s commitment to make charging easier for renters and flat-dwellers [points to] a future where nobody is left behind in the switch to electric simply because of where they live,” said  John Lewis, CEO of lamppost charging maker char.gy. “Lamppost charging has always been about meeting drivers where they are, using infrastructure that’s already on every street in the country.”

Kerbo Charge makes a clever low-tech solution: a metal channel that can be installed across a pavement (what we Yanks call a sidewalk), allowing city-dwellers to run a charging cable to their EVs with no trip hazard. The company’s CEO Michael Goulden said: “We’ve long called for the government to cut through the red tape that has been holding back cross-pavement charging, and today’s commitment to introduce permitted development rights this summer is exactly the kind of decisive action needed. This opens the door to genuinely affordable EV ownership for the millions of drivers who’ve been locked out simply because they don’t have a driveway.”

March 2026 was a record month for EV registrations in the UK—battery electric vehicles accounted for 22.7% of all new car registrations, an increase of 22.6% year-on-year.

Sources: Gov.uk, Kerbo Charge, char.gy

Coke Canada Bottling has added seven Volvo VNR Electric trucks across two provinces, bringing its total Canadian electric fleet to nearly 40 vehicles. Three trucks have arrived in Quebec City; four more are set for delivery this spring in Vancouver.

The VNR Electric runs a six-battery configuration covering up to 440 km (275 miles) on a single charge, enough for several daily round trips between distribution centers and customer locations. To support the expansion, the company installed one 180 kW Heliox Flex charger with three dispensers in Quebec City and two 180 kW Heliox Flex chargers with six dispensers in Vancouver.

The family-owned company launched its electric pilot in Montreal in 2023. Its fleet now spans vans, on-road trucks and yard tractors, all on local and regional distribution routes where predictable, high-frequency operations suit battery-electric technology. The new Volvo trucks serve Coke Canada’s Lower Mainland and Quebec City regions.

“Coke Canada Bottling has taken what they learned early on and turned it into a practical, multi-region deployment,” said Matthew Blackman, managing director, Canada, Volvo Trucks North America. “When you see electric trucks running predictable, high-frequency routes like these, it shows how well the technology fits into everyday fleet operations.”

Source: Volvo Trucks North America

Lots of things go better in the open air: picnics, concerts, sports. But battery farms?

At a pilot program near Reno, battery recycling pioneer Redwood Materials has mounted rows of second-life battery packs in the open air on above-ground cable trays.

Spreading packs out in the open air helps avoid the need for active refrigeration, and eliminating moving parts like fans and filters minimizes potential malfunctions. Keeping the wiring above ground and limiting the size of each modular component minimizes the need for large equipment.

This innovative battery-farm design is part of a pilot program to power four data centers, operated by Crusoe. Redwood installed a 20 MW solar system and 12 MWh of repurposed batteries. Following the successful pilot, Crusoe agreed to the installation of similar systems at 20 more data centers.

Redwood runs the battery packs at only a fraction of their original power capabilities—this development decision sacrifices maximum output in favor of safety, longevity and easier thermal management—it’s one of the keys to avoiding having to run an active refrigeration system, even in hot Nevada summers.

Redwood has developed a proprietary pack management technology that lets it communicate with and control batteries of different voltages, protocols, and states of health. The pack manager is a universal adapter for EV batteries, performing power conversion into a unified DC stream that can work with any standard inverter. The site controller aggregates many packs into one coherent storage system, balances state of charge across packs, and intentionally “unbalances” some based on their health—older packs are cycled more gently, while fresher packs get worked harder. The battery algorithms team is continually updating models to track the health of each pack from receipt through its repurposed life, and eventually to recycling.

Source: Latitude Mediavia CleanTechnica

Samsung Electro-Mechanics is mass-producing a new set of ultra-high-voltage multilayer ceramic capacitors (MLCCs) rated from 1000 V to 1500 V, extending its C0G and X8G temperature-stable series to cover 800 V EV inverter systems and next-generation onboard chargers.

All four devices share a 1210 package (3.2×2.5 mm) and hold capacitance within 0±30 ppm/°C across the operating range—C0G specified from –55 to 125 °C, X8G from –55 to 150 °C. Capacitance runs from 1.2 nF at 1500 V to 33 nF at 1000 V. Three of the four carry a fail-safe design designation.

The target applications are the resonant tank circuits (CLLC topology) in EV charging systems and snubber capacitors for suppressing switching transients in inverter power modules. As next-gen OBC output power climbs beyond 22 kW, component voltage and capacitance requirements rise with it—higher-voltage, stable-dielectric MLCCs let designers maintain power density without sacrificing reliability.

C0G and X8G dielectrics deliver near-zero capacitance drift over temperature. That matters in resonant converter designs because capacitance directly sets the resonant frequency; any drift shifts the operating point and affects efficiency. Extending this level of stability to 1000–1500 V is what the 800 V powertrain generation demands.

The parts are in mass production. Samsung Electro-Mechanics offers technical support and samples for customer-specific designs.

Source: Samsung Electro-Mechanics

cellcentric, the fuel cell joint venture of Daimler Truck and the Volvo Group, has officially named its next-generation heavy-duty system the BZA375 and launched it at Hannover Messe. The system delivers up to 375 kW of continuous net power—more than 500 hp—from a single package, replacing the twin-system approach previously required with its predecessor, the BZA150.

Compared to BZA150, the improvements are substantial across every metric. Fuel consumption drops 20%, putting a fully loaded 40-ton truck under 6 kg of hydrogen per 100 km under real-world conditions and enabling ranges beyond 1,000 km. Waste heat at 300 kW net power falls 40%, enabling more compact cooling systems. Power density rises 40%. Component count drops 40%. Weight comes in under 500 kg, keeping payload at diesel-equivalent levels. The system is dimensioned to fit engine compartments designed for conventional 13-liter diesel engines. Service life holds at 25,000 hours—equivalent to 10 years in a heavy-duty truck—maintained from BZA150.

Moving to a single system is the key architectural change. BZA150 required two units running in parallel to meet heavy-duty truck power demands. BZA375 handles the full load alone, reducing integration complexity and giving OEMs more flexibility in vehicle packaging.

Beyond trucks, cellcentric positions BZA375 for coaches, rail, mining and stationary power generation under a one-product strategy, using volume across applications to drive costs down.

“BZA375 is custom tailored for the needs of heavy-duty, long-haul trucks,” said Nicholas Loughlan, CTO of cellcentric. “At cellcentric, we are deliberately set up as an independent Tier 1 supplier and open to partnering with any OEMs that are driving the decarbonization of their portfolios.”

“Two key technologies will lead the way on our path to decarbonize transport: battery-electric and hydrogen,” said Karin Rådström, President and CEO of Daimler Truck AG.

Prototype systems are now available to customers for testing and validation. Before series production begins, larger volumes of mature prototypes will be made available for initial fleet applications. Series production is being prepared for the turn of the decade.

Source: cellcentric