What is the difference between H1 and H7 car bulbs?
2 Answers
The difference between H1 and H7 car bulbs lies in the number of wiring terminals: the H1 has one wiring terminal, while the H7 has two wiring terminals. The similarities between H1 and H7 car bulbs are: both are available in halogen and xenon versions. The working principle of halogen bulbs is: halogen gases such as iodine or bromine are injected into the bulb. At high temperatures, the sublimated tungsten filament reacts chemically with the halogen, and the cooled tungsten re-solidifies on the filament, forming a balanced cycle that prevents the filament from breaking prematurely. The working principle of xenon bulbs is: inside an ultraviolet-resistant quartz glass tube, various chemical gases are filled, and then the vehicle's 12-volt DC voltage is instantly boosted to 23,000 volts by a booster. The high-voltage amplitude excites the xenon gas electrons inside the quartz tube to become free, generating a light source between the two electrodes.
I used to change car lights by myself quite often and compared H1 and H7 bulbs. The H1 bulb has a metal tail at the back and requires fixing with a nut. Changing it involves screwing, and those with clumsy hands might easily break the wires. The H7 is much simpler—just insert and twist the three claws, and it's done. There's a significant difference in brightness. At the same 55W power, the H7's luminous efficiency is over 20% higher, providing more even road coverage with low beams at night. Older cars often used H1 for high beams, while mainstream models now mostly use H7 for low beams. There's also a big gap in lifespan—the H1 typically burns out after about 500 hours, whereas the H7 can last up to 1,000 hours. If you want to upgrade, you'll need to replace the dedicated base; direct replacement isn't possible, or it won't secure properly.
