I think it would be good if we can find an H4 LED bulb that is similar to a halogen bulb for the power savings. I had to go with a small alternator for my build for fitment and I’d like to save as much juice as possible for the battery. Replacing all the bulbs on the truck with LEDs saves a lot of energy.
To be like a halogen bulb it needs to be not overly bright so as not to dazzle oncoming drivers, doesn’t destroy the beam pattern, and has halogen color.
I ordered this one to test. It’s POLARG brand by Nissei, which is a Koito company. It’s from Japan; not Chinese. It’s close to halogen color at 4200K, rated 2800 lumens low beam and 3000 lumens high beam. The base is the same size as a halogen bulb so the original rubber cover can be used. It consumes 12 watts, so that’s a savings of 86 watts for the pair over 55 watt halogen bulbs.
日星工業株式会社 - POLARG LED電球ヘッド＆フォグシリーズ
Here’s a driving review: (If you want to know what he's saying select subtitles with auto translation to English)
The end of this video shows what it looks like from the front of the vehicle:
I also ordered these IPF T10 LED bulbs to test for the side lights. That would save 18.4 watts replacing all 4 of them. They have about the same brightness as the incandescent bulbs.
I'm going to try these 130 lumens IPF bulbs in the rear high mounted brake light. They are 1.15 watts so 3 of them saves 11.55 watts.
Here are a few other H4 LED bulbs that can be considered.
M’s Basic by IPF (this is a line made exclusively for Amazon). It’s 4000K color and 3200 lumens low beam, but it consumes 25 watts, so it isn’t as efficient. One reviewer said it’s a little more bright than the 4200K POLARG, but was less uniform so visibility didn’t increase.
Carmate GIGA 5000K. A little more white color. This one is made in China, but it’s a major name brand in Japan. Low beam is rated 3200 lumens and it consumes 26 watts.
If you want really bright here’s a Sphere Light 4500K one that is 6000 lumens rated, but it consumes 31 watts and it’s quite expensive.
POLARG also makes a bright one at 5000 lumens which consumes 25 watts, but it’s 6500K color and only sold at Autobacs (not available from Amazon).
There is also a middle-tier version at 3200 lumens which consumes 14 watts, but it’s also 6500K color.
It looks like POLARG has some of the most efficient LED bulbs on the market. Many of the random Chinese LED bulbs on Amazon consume more power than halogen bulbs and aren’t as bright as they claim.
Stanley appears to be one of the only other OEMs that makes H4 LED bulbs besides Koito (POLARG), Osram/Sylvania, and Philips. Here’s one, but it’s 6300K color and quite expensive. It’s rated 3200 lumens low beam and consumes 24 watts.