How To Tell If Bike LED Light Bulb Is Blown?

How to Tell if Bike LED Light Bulb is Blown

Cycling is an exercise better enjoyed at night due to the less traffic and cool weather. However, there are also risks of accidents due to reduced vision.

Hence, most cyclists use light bulbs, primarily LEDs, since they shine brighter.

However, you may notice your LED light bulb isn’t coming on after multiple attempts. Does that mean it’s damaged or blown?

When your LED bulb doesn’t come on again, you need to test it by connecting the bulb to a battery to confirm it isn’t working. If the light doesn’t turn on, your bulb is blown. This dilemma is inevitable as the bulb is subject to loose connections and wires. Therefore, you must replace it immediately.

Can Bike LED Light be Blown?

How to Tell if Bike LED Light Bulb is Blown

It is possible for LED bulbs on your bike to blow, although these bulb types are known to be more durable.

It usually happens in cheap LED bulbs made from weaker elements, making them vulnerable to the least amount of power issues.

Another cause could be poor or loose wiring connections if you use a bike dynamo for bike lights. 

The wiring could loosen due to vibrations and shocks caused by bumping into obstacles when cycling. This could happen to the wire or plug hence the need for a replacement.

But first, confirm the insulation wire is the problem behind the blown LED dynamo bulb. If it is, replace the lighting wire and bike plugs. 

The dynamo differs from battery-powered LED lights and works by generating electricity through pedaling.

This dynamo has a wheel in proximity to the rear tire. When you pedal the bike, the electromagnetic operation occurs, inducing sufficient electricity to run the bike’s LED light.

These dynamo hubs come in different sizes to fit all wheels because smaller wheels rotate quicker than big ones at whatever speed. 

Hence, when cycling at high acceleration, using a dynamo made for 700c tires on a 20-in folding bicycle maximizes the likelihood of blowing your LED bike light due to high voltage.

Therefore, if you use dynamo LED bulbs instead of battery LEDs, use the appropriate wheels with their dynamo hubs.

3 Signs that my Bike LED Light is Blown

The most obvious sign you have a blown LED bulb is that it won’t come on.

But fortunately, you’ll be given some signs beforehand to notice this and replace the bike LED lights as soon as possible.

Below are indications to watch out for in this case.

#1. Dimmed Lights

The first and most prominent indication of an LED about to fail is dimmed lights. LED bulbs are known for their maximum shine, which is brighter than other bulbs of the same wattage.

But when their brightness reduces, know that something is off, and they’ll burn out very soon.

They’ll continuously dim until they properly blow out, so get a replacement when you notice this abnormality.

#2. Flickering Lights

Another unusual occurrence signaling a blown bulb is flickering lights. It flashes on and off due to worn-out filaments.

These bulb filaments are responsible for emitting the bright light in LED, so damaged or worn-out filaments will cause the bulb to stop giving off light, resulting in a failed LED bike light. 

#3. Burning Smell

Burning smells are unusual in LED bulbs, but it is likely due to overheating when they occur.

This usually happens in low-quality LED bulbs, and the overheating can destroy vital elements like capacitors causing which reduces the bulb’s longevity, causing blowouts.

How can I Tell if my Halogen Bulb is Blown?

You can confirm if your halogen bulb is blown differently, but the most accurate method is using the multimeter.

Before explaining how to conduct a multimeter test, let’s consider other ways to check for a blown halogen bulb.

#1. Check the Filament

Your halogen bulb’s filament is vulnerable to sudden electrical current increase, which could cause burnt or broken wires.

Check the bulb’s filament for any dark layer around its glass, which is a sign of burnt filament due to overheating. 

However, this method isn’t entirely reliable as bulb filaments are thin, and since these black coatings aren’t regular, you may not know of any problems till later.

#2. Shake the Bulb

Shaking the bulb helps you discern if it’s blown since the first filament method might not always work.

A good bulb should make no sound when shaken, but if yours makes a rattling sound, the filaments are broken.

However, the downside is that the rattling sounds don’t always imply the bulb has issues.

#3. Look for a Bubble

Halogen bulbs are vulnerable to contaminants such as oil or dust, so if you notice any bubble in the bulb, it is likely a pollutant.

While halogen bulbs can work with contaminants, these bubbles can lead to cracks and clearly show the bulb is about to be blown.

#4. Multimeter Test

The multimeter offers a more reliable answer since it operates on a bulb’s voltage, resistance & electric current.

This device helps determine a blown bulb regardless of filament or contaminant problems.

#1. How it Works

  • You’ll have to put the multimeter’s dial to Ohms to help you gauge resistance.
  • Next, experiment with your multimeter. It has two pointers: black (negative) and white (positive). Connect the black lead to the COM socket and the red one to the volt outlet.
  • Connect the two probes of your multimeter and inspect if the reading is in or close to zero. If so, it works fine, and you can begin your halogen bulb test.
  • Connect your pins and connect two small test probes to your halogen bulb. Attach one to the bulb’s rear and the other to the casing.
  • Check the reading to see if it is below or above zero. Below zero means a blown bulb, and above zero means it’s functioning fine.

Why did my LED Light Suddenly Stop Working?

Several problems could stop your LED light from working, and the table below lists some of them & practical solutions to help fix them.

Causes and ProblemsSolutions
Your LED bulb is loosely attached to the bulb holder. You can effortlessly fix this by checking if the holder has a bent or broken connection. If there’s none, screw your bulb tightly, but if necessary, replace the bulb holder.
Faulty wiring connectionsHave a professional check your LED light bulb installation to confirm if you have any burnt or loose wires and replace them.
Using the wrong dynamo hub and bicycle wheels at high speed causes overvoltage, which damages your LED bulbs.If you’re using dynamo bike lighting, check that the dynamo hub your bicycle is using is compatible to avoid high-voltage issues and blowouts.
A drained LED bulb battery.If you’re using a battery-powered LED bulb, ensure to charge it before use and if it no longer works, get a replacement.

While LED bulbs are durable, they also have a longevity period, so that it could be they’ve exhausted their lifespan.
You need a LED bulb replacement.
Exposure to water and humid atmospheres affects the LED bulbs, instantly shorting them.Choose waterproof LED bulbs for your bike and buy IP65 LED bulbs as they’re excellent and the highest choice in waterproof bike lights.


While many uses LED bike headlights for night vision, others prefer them for their color variety, durability & bright white light.

However, LED bulbs aren’t susceptible to damage or early failure like other bulbs.

Hence, endeavor to check for early signs of blown bulbs using reliable methods and professional assistance for immediate replacement of any damaged parts.

Josh Matthews

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