Amazon Rechargeable COB Light: A Thorough Review

This is a COB light I got for about 1000 yen at the Bakuretsu Matsuri merchandise event, three years ago (as of the time of writing, winter 2025).

When I bought it, I simply thought it was a nice, compact, and convenient light, but recently, after doing some more research, I realized for the first time that it's a trendy COB light.

The model is exactly the same as the one sold on Amazon for around 500 yen.

It's a little frustrating that something I bought for 1000 yen is now being sold for around 300 yen, but since it's a very convenient item for everyday use, I'll go ahead and review it.

What is COB lighting?

Before we check out the actual product, let me briefly explain COB lights.

COB stands for Chip On Board Light, and as the name suggests, it is a technology that mounts multiple LEDs onto a single circuit board.

What is commonly called an LED has the configuration shown in the following diagram.

They can be broadly categorized into two types: bullet-shaped and surface-type, but they are basically composed of a single LED.

To increase the light output of this type of LED, it is necessary to either improve the LED unit element or enlarge the LED itself. Generally, enlargement is the more common approach, but the larger it gets, the more heat is generated, leading to various problems such as malfunctions (and the price also increases).

One solution to the problems of increasingly large and costly LED units, and the numerous heat-generating issues, is the Chip On Board LED (COB light for short).

Chip-on-board LEDs are a technology that mounts multiple LEDs onto a single circuit board using a light-reflecting sheet base, as shown in the diagram below. Essentially, multiple LEDs are directly placed on an aluminum sheet.

This eliminates the need for expensive, heat-generating large LEDs to achieve high light output; bright lights can be created using readily available, inexpensive LEDs that have become cheaper through mass production.

COB LEDs are low-cost, offer high brightness, low heat generation, and a long lifespan, but because they are a combination of small LEDs, they are not suitable for illuminating long distances with strong light like bullet-shaped LEDs. Therefore, I think they are best suited for use as a light source to illuminate nearby areas (everything has its pros and cons).

I believe the reason this COB (Chip-on-Blade) technology became possible is due to control technology that can distribute electricity evenly to multiple LEDs.

Such technological innovations are common not only in the electronics and electrical fields, but in my area of ​​expertise, mechanical engineering, rocket engines are a prime example.

The Saturn V rocket, a representative American rocket used in the Apollo program, employed a combination of several high-performance, massive engines (five F-1 engines; the Space Shuttle also used a similar concept).

On the other hand, the Soviet Soyuz used multiple small rockets bundled together (16 RD-107 rockets).

While the Soviet Union lost in high-power, one-off battles like the race to the moon, you may know that they dominated the market for general-purpose space transport, surpassing the Space Shuttle (in terms of reliability and cost).

I've jumped around quite a bit in my explanation, but I think it's interesting that the underlying philosophy behind this kind of technology is the same for cutting-edge rockets and even for inexpensive, everyday lights like the one I'm introducing today.

Red Moon Shock
This is a non-fiction book about the early days of space exploration, specifically the US and Soviet rocket development. It provides a very detailed description of the differences in their approaches to rocket engine development. If you're interested, I highly recommend it!

Opened

Let's start by looking at the outer box.

The side of the box lists the product's features.

It is manufactured in China. We will look at each function in detail later.

Let's open it and check the contents.

It's really great that a charging cable is included.

The instruction manual is only in Chinese and English, with no Japanese, so I will explain the basic usage on this page.

appearance

Let's start by looking at the front of the unit.

It's a very compact device. The features visible from the front are a carabiner, bottle opener, and COB light unit. The COB light unit has 30 LEDs.

Let's take a look at the back of the device.

On the back, you can see a magnet and a stand for placing a light.

Let's take a look at the left and right sides of the main unit.

The switch is located on the left side, and the charging port is on the right side.

Finally, let's look at the bottom of the unit.

The bottom has a standard U1/4 screw hole for attaching a camera tripod.

In terms of size, it looks like this when placed in the palm of your hand, as shown in the following photo.

The detailed dimensions are as shown in the following photo.

It's the weight.

Features

Let's take a look at the actual functions.

First, let's look at the power button.

The buttons are made of rubber and don't have a light feel when pressed; they're not the easiest switches to press. However, if they were too easy to press, there would be issues with accidental activation, so it seems to be a matter of personal preference.

The button modes follow a somewhat complex pattern, as follows:

It's quite puzzling that the 100% mode, which will likely be used most often, requires a long press of a button.

We will show you what it looks like when it's actually lit up in a separate section.

Next, let's look at the charging port.

The charging port is covered with a sturdy rubber cover, so you might think it's waterproof, but there's no mention of waterproofing in the packaging or instructions. Therefore, it's probably best to assume it's only protected against minor splashes of water or dust.

You can charge the device by plugging a USB Type-C cable into the port (a cable is included). The indicator light will glow red while charging and turn blue when charging is complete.

According to the manual, the battery is a 500mAh lithium polymer battery. It's probably a single cell at 3.7V.

According to the sales website's description, the continuous operating time is 1 hour at 100% brightness, 1 hour and 40 minutes in 60% brightness mode, and 3 hours at 30% brightness, but this is probably the time until the battery is completely discharged.

Lithium polymer batteries will break if completely discharged, so it is not recommended to use them to their limit (they usually break if 20-30% of their capacity is not left).

Ideally, electronic devices that use lithium polymer batteries should constantly monitor the voltage and stop operation if an abnormal voltage (too high or too low) is detected, but in actual use, such a function doesn't seem to be present (and the price also suggests it's not).

Therefore, the recommended continuous operating time and usage are as follows.

・100% light intensity mode... 45 minutes

・60% light intensity mode: 1 hour 15 minutes

・30% light intensity mode: 2 hours 15 minutes

If you don't know the operating time, it's best to stop using it when the light becomes dim.

- It doesn't seem to have an automatic shut-off function when fully charged, so you should avoid leaving the USB plugged in when it's fully charged.

Looking at actual product reviews, there seem to be some battery-related issues, so I think it will last longer if you take care of that.

Next, let's look at the carabiner and bottle opener.

The carabiner itself has a strong attachment mechanism, making it very convenient. Because the main body is lightweight, I use it to attach things to zipper pulls on bags and backpacks or to belt loops on my pants.

However, the main body and carabiner are made of cast aluminum, and the pin part seems weak, so I think it's best to avoid pulling on it too hard.

The bottle opener part is made of cast aluminum and lacks a sharp point, so I think it's practically useless. Besides, I can't really think of many situations these days where you'd need a bottle opener.

Let's take a look at the stand.

The stand offers a total of three adjustable angles.

It's easy to use thanks to its perfectly balanced angle. The only drawback is that, being lightweight and compact, it tips over easily.

Let's take a look at magnets.

The magnet isn't particularly strong, but it provides enough support to hold the device in place, which I think is sufficient. In fact, if the magnet were too strong, it might negatively affect nearby electronic devices, so this might be just the right strength (am I being overly concerned?).

Finally, I actually attached the tripod to it.

The screw part is made of resin, and the engagement point is only about 5mm, so I have serious concerns about its strength. While it's fine for simply resting it on something because the main body is lightweight, I feel like the screw part might break if it's accidentally knocked over.

Make it actually light up

Now we'll actually make it light up.

The conditions before the light is emitted are as shown in the photo below, where it is almost completely dark and nothing can be seen. The distance between the light and the object is approximately 2 meters, and we will compare each mode from this distance.

1. Press and hold the button to set the light intensity to 100% (recommended continuous operation time: 45 minutes).

It's quite bright, and even small print is easily readable. It's dimmer than the room's lighting, but it's bright enough to live in a room of about 6 tatami mats.

2. Press the button once to enter 60% brightness mode (recommended continuous operation time: 1 hour 15 minutes).

The brightness is decent, and you can even read small print. It feels like it's just about livable in a room of about 4 tatami mats.

3. Press the button twice to enter 30% brightness mode (recommended continuous operation time: 2 hours 15 minutes).

It's definitely a bit too dark. It's difficult to read small print.

4. Press the button three times to activate the flash mode.

Since it cannot be depicted in still images, this is a video. Please be careful when watching as it flickers.

Strobe mode is flashing, so be careful.

Looking at it with such a powerful strobe light makes me feel sick. This isn't just limited to this light, but I don't really understand the purpose of the strobe mode.

Summary and similar products

This light is packed with so many features that I don't use some of them, but as a light, it's incredibly well-made and very useful. The fact that it's so affordable for this level of quality is amazing.

I especially appreciate that it's rechargeable. I'm frugal, so with proper flashlights, I tend to be hesitant to use expensive CR123 batteries, but since this one is rechargeable, I can use it freely without worrying.

I frequently use it as a light source when searching for things, and it's incredibly convenient. Even in bright environments, the light output is strong, so it clearly illuminates dark areas, which is extremely helpful.

Furthermore, it's incredibly useful as a light source for packing up outdoors as the sun begins to set. Especially outdoors, its compact size and carabiner make it very convenient to attach to your belt or jacket zipper, allowing for quick access (it's a hassle to get out a proper flashlight).

The drawbacks are that the unit lacks a battery management function and it doesn't have enough power or sustain to be used as a serious outdoor light source (like a lantern).

Considering that I purchased this for 1000 yen, and the current market price at the time of writing is around 500 yen, I think it's quite reasonable.

From here, we'll introduce similar products and check the key points of each.

Amazon COB Light
This is the same product I introduced. However, there seem to be differences in specifications depending on the lot, and the carabiner part may sometimes be a wire type. It is sold in various forms by various distributors and online stores, but I think most products priced around 500 yen are this one.

Musashi COB Light
It's a complete upgrade. The brightness and functions are the same, but being made in Japan, it seems to be very well-made. In particular, it has battery quality and charge/discharge check functions, so the battery life and duration are significantly better and easier to manage, so you can use it with peace of mind (this is a mandatory feature under product liability laws). However, it is more expensive than the product I introduced earlier.

OHM Electric COB Light
Although it's made in China, it's officially sold by a Japanese company, so I think the quality control system is quite high. The contents are probably almost the same as the one I introduced, but I think the chances of getting a defective product will be greatly reduced.

Personally, I wouldn't recommend carabiners with wire clips or those made of resin. Since they're already made of aluminum and are quite lightweight, I don't see much benefit in sacrificing durability to make them even lighter. It might be a different story if the price were significantly lower, but because they're already inexpensive, the disadvantages seem to outweigh the advantages.

That concludes my review of the COB light.