Sourcing car chargers

Load dump. When a charging battery is disconnected while the alternator is delivering current, the supply voltage rises sharply for a short time. It is the classic destroyer of unprotected automotive electronics, and surviving it is a design decision — input protection components, their rating and their energy handling — not a matter of luck.

Cold cranking. Starting the engine drags the supply down briefly. A charger that resets, or that confuses the device it is charging, every time the engine starts is a product with a daily annoyance built in.

Transients and noise. Every relay, motor and switch in the vehicle puts something on the supply. This is why input filtering and the protection network matter more here than in almost any consumer product.

The tests that cover all three. ISO 7637-2 covers electrical transients conducted along supply lines; ISO 16750-2 covers electrical loads including load dump and cranking. Ask which of them the design has been tested against, at which levels, and by whom — and ask for the report rather than the assurance. A supplier who can answer is a supplier with an automotive engineer; one who cannot is selling a wall charger in a cylinder.

Test levels are not published here on purpose. They belong to the standards and vary by level and by application, and a number quoted second-hand in a guide is exactly the paraphrase this project does not publish.

The parked car is the thermal case. Interior temperatures in the sun far exceed any indoor test, and a charger that throttles or shuts down there fails in precisely the hot markets where it sells best. Specify the ambient temperature range and test at the top of it, with the charger at full output.

Retention in the socket. Sockets vary in diameter, depth and spring tension, and they wear. A charger that falls out of an older socket, or one that only makes contact intermittently over bumps, generates returns that look like electrical faults. Test in several vehicles of different ages, not one.

The fuse. Most cylindrical chargers carry a fuse in the tip. Ask for its rating and type, and whether the user can replace it — an inaccessible fuse turns a survivable event into a dead product.

Cable pull and connector strain. Users unplug by the cable. Specify a pull test and check what happens to the internals when they do — a joint that fails inside the barrel is a fault that intermittently appears months later.

Materials and flame rating. A device that lives in a hot enclosed space near flammable trim deserves a specified enclosure material and flame rating, and the marking on the product should say what it is.

Protocols and revisions. Specify the USB Power Delivery revision, the fixed profiles you require, and whether PPS is needed — the same discipline as a wall charger. Then test with the devices you actually sell alongside.

Per-port and combined output. A two-port car charger advertising a large total figure usually cannot deliver its headline single-port output while both ports are in use. Ask for the allocation table for every combination and put it in the specification.

Sustained output at temperature. Anything can hit its rated output cold for thirty seconds. Ask what it delivers after twenty minutes at the top of the specified ambient range, and test that in a vehicle in the sun.

And do not let a bundled cable undercut the claim. Above a certain current a USB-C cable needs an e-marker to negotiate at all, so a high-output charger bundled with an unrated cable silently delivers less than the box says.

Certification. Radio approval does not usually apply to a passive charger, but destination product-safety obligations and, in several markets, efficiency and marking requirements do — and the party placing the product on the market under its own brand carries them, not the factory.

Business licence and business scope (经营范围) first, then one question that sorts the category quickly: has this design been tested to the automotive transient standards, and can I see the report? Very few consumer car-charger suppliers can say yes, and the ones who can are a different tier.

Ask what is tested on the line — output regulation, a burn-in, and ideally a surge or transient screen. And ask what the field return rate is and what the dominant failure mode was; a factory that knows is a factory that measures.

Test in cars, not on a bench. Several vehicles of different ages, engine starts, a full day parked in the sun, and unplugging by the cable a few hundred times. That programme finds nearly everything.

Then take one apart. Input protection components and their ratings, the fuse, the filtering, potting or its absence, the thermal path to the shell, and the strain relief inside the barrel.

Every supplier on this site is a manufacturer, and the registered-scope check is one of the things confirmed before a listing goes live.