Choosing the right ballast is one of the most overlooked parts of building a reliable HID system, and it is a question we get almost every day here at TRS. In this HID ballast comparison, we walk through the four options we tested side by side: the Matsushita, the Denso, and both the Morimoto 55W and Morimoto 35W units. Each has its own strengths, and understanding where they differ (warm-up speed, weatherproofing, wattage output, and mounting flexibility) will help you decide which one belongs in your project.
We put these ballasts through their paces on the bench so we could speak from hands-on experience rather than spec sheets. Below, we break each one down the way Zach walked through them in the video, and we point out the practical differences that actually matter when you are wiring up a car. If you are still deciding whether to go the HID route at all, it helps to first understand why projector retrofits make sense before you invest in the electronics that feed them.
Matsushita Ballasts: OEM Reliability From Infiniti and Nissan
The Matsushita ballast is one you will find under the hood of many Infiniti and Nissan vehicles as factory equipment, which is exactly why its reliability is so well known. When a ballast has been running in OEM applications for years without issue, that track record speaks for itself. We tested these and found the startup performance to be excellent, with an incredibly fast warm-up time in how quickly it brings the bulb up to full brightness.
One thing to keep in mind with the Matsushita is how it handles moisture. Internally, it uses a gel-coated circuit board to help combat any moisture that may get inside. That is a meaningful protective layer, but it is important to understand the limits of that design. The casing itself is not weatherproofed, so you will want to mount it in a location that stays reasonably protected from the elements. Gel-coated circuit boards help resist moisture inside the ballast casing.
If you are shopping the OEM-style route, the Matsushita Gen V 35w HID Ballast is a great example of the kind of proven hardware that made these units so popular in the first place. You can also browse our full OEM HID ballast lineup to compare the different factory-derived options we carry.
Denso Ballasts: The Toyota and Lexus Counterpart
The Denso ballast is a very comparable unit to the Matsushita, and it comes from the other side of the OEM world. You will find these in Toyota and Lexus cars as factory equipment, which gives them the same kind of reliability pedigree. In our testing, the Denso also delivered an extremely fast startup and warm-up time for the bulbs, right in line with what we saw from the Matsushita.
The Denso shares the same moisture strategy as the Matsushita. It also uses a gel-coated circuit board to help fend off moisture that might work its way inside, but again, the casing itself is not weatherproofed. So when you are deciding between the Matsushita and the Denso, the choice often comes down to what fits your application and what you can source, since the two perform so similarly. Both are excellent, proven OEM options.
If you want to see how these factory units are packaged together in a complete kit, the D2S OEM HID system with Denso and Matsushita ballasts is a good reference point for how the OEM hardware comes together as a system.
Morimoto Ballasts: Slim, Weatherproof, and Flexible
Now we move on to the Morimoto versions, and this is where the design philosophy shifts a bit. While the Matsushita and Denso are OEM-derived units, the Morimoto ballasts are purpose-built for the aftermarket, and it shows in a couple of key ways.
First, the warm-up time. In our testing, the Morimoto ballasts have a very fast startup, and we consider them second only to OEM ballasts in how quickly they bring the bulb up to full brightness. That is a strong result, because the OEM units set the bar. Getting that close to factory performance in an aftermarket ballast is exactly what you want.
Second, the physical design. The Morimoto ballasts use a very slim form factor, which opens up a wide range of applications and mounting options. If you have ever fought to find a spot for a bulky ballast in a tight engine bay, you will appreciate how much easier the slim profile makes life. This flexibility is one of the biggest practical advantages over the more traditionally sized OEM units.
Wattage Output: Honest Numbers
One of the things we like most about the Morimoto lineup is that the wattage output is honest. The 55W version puts out a true 50 watts, and the 35W version puts out a true 35 watts. There is no marketing inflation here, and knowing the real output helps you match the ballast to your bulb and expected brightness without guesswork.
If you are leaning toward the aftermarket option, the Morimoto XB 35w AMP ballast is a solid starting point, and you can explore Morimoto’s full ballast selection to see the different versions available.
Weatherproofing and the Included Grommet
This is where the Morimoto ballasts really separate themselves from the OEM units. Both the 55W and 35W versions are fully weatherproof with potted internals. That means the electronics are sealed against moisture, so you do not have to worry about water intrusion damaging them. Combined with the slim design, this gives you even more freedom in choosing where to mount them, including locations that would be risky for a non-weatherproofed ballast.
The Morimoto ballasts also come with a grommet to seal up the headlight housings if necessary. This is a thoughtful touch, because it helps keep moisture out of the housing itself when you route your wiring through. Little details like this are the difference between a clean, lasting install and one that fogs up down the road.
Putting It All Together
When we line all four up side by side, the picture becomes clear. The Matsushita and Denso are proven OEM ballasts with gel-coated circuit boards and lightning-fast warm-up times, but their casings are not weatherproofed, so mounting location matters. The Morimoto units trade a hair of warm-up speed (still second only to OEM) for a slim design, honest wattage output, full weatherproofing with potted internals, and an included grommet for sealing the housing.
So which one is right for you? If you want that OEM pedigree and you have a protected mounting spot, the Matsushita or Denso will serve you well and start up incredibly fast. If you need mounting flexibility, want to tuck the ballast into a less protected area, or simply prefer the peace of mind of fully weatherproof internals, the Morimoto is the smart call. Either way, all four are quality units, and this HID ballast comparison should give you the confidence to pick the one that fits your build.
Frequently Asked Questions
What vehicles use Matsushita HID ballasts?
Matsushita ballasts are found under the hood of many Infiniti and Nissan vehicles as the OEM ballast, and are known for their reliability.
Are Matsushita and Denso ballasts weatherproof?
No. Both Matsushita and Denso ballasts have gel-coated circuit boards to help resist moisture, but their outer casings are not weatherproofed.
What vehicles use Denso HID ballasts?
Denso ballasts are the OEM ballast found in many Toyota and Lexus vehicles and perform very comparably to Matsushita units, including a fast bulb warm-up time.
How does the Morimoto ballast warm-up time compare to OEM units?
The Morimoto ballasts have a very fast startup time, considered second only to OEM ballasts in how quickly they bring the bulb up to full brightness.
What wattage options are available with Morimoto ballasts, and are they weatherproof?
Morimoto ballasts come in a 55W version that puts out a true 50 watts and a 35W version that puts out a true 35 watts. Both are fully weatherproof with potted internals and include a grommet to help seal the headlight housing.
Meet the Experts Behind The Retrofit Source
Tyler Jordan – Technical Writer
Tyler works directly with the TRS product R&D team, bringing over a decade of automotive aftermarket lighting experience to every article. An avid enthusiast with hundreds of personal installations under his belt, his content is built on hands-on knowledge from the workbench, not spec sheets.
Caleb Morgan – Marketing Manager
Caleb brings over a decade of automotive lighting industry experience and works with TRS customers daily on the front lines. With hundreds of personal lighting installations and a direct feedback loop from real buyers, his content addresses the questions and problems that actually matter.
