Can You Charge a Solar Light with Flashlight?

By Matthew Joseph Nandirio •  Updated: 01/12/23 •  5 min read

Solar lights are widely used for lighting up outdoor spaces as well as indoor spaces.

Because they are an eco-friendly and cost-effective light source.

However, what happens if you do not have access to direct sunlight? Can we charge a solar light using a flashlight or else it is a useless effort?

Is it possible to charge a solar light using a flashlight or any other light source?

Can you charge a solar light using a flashlight?

Let’s have a look and see about that.

By the way, I did an experiment to check this rather than going to cite other online sources.

Can you Charge a Solar Light with Flashlight?

Yes, Solar light can charge through a flashlight. But the flashlight needs to produce the correct and stable intensity and spectrum of light that is required to charge solar light.

Typically most solar lights want an intensity of a minimum of 50 lux for effective charging as well as a wavelength of 400 to 700 nm spectrum range.

And also the battery life of the flashlight is more important Since it will take several hours to fully charge the solar lights.

The main problem with the flashlight-based charging method is that you have to spend a lot of hours to fully charge your solar lights. Artificial solar light efficiency is drastically lower than direct sunlight.

These photographs from my experiment clearly define the difference in current generation rates under artificial lights and direct sunlight.

The flashlight generates only 0.7 mA or nearly 1 mA current and in contrast, direct sunlight produces 64.21 mA of current.

Now you have a clear idea of why you have to wait a long time to recharge your solar lights with the flashlight.

You can watch my experiment in this video

You can watch the above video of mine. It clearly shows how I measure the current variations of garden solar light and motion activated solar light under direct and flashlight.

The difference is noteworthy.

How can you charge solar lights using a flashlight?

Here I’m going to simply explain the steps need to follow solar light charging through a flashlight.

You don’t need any technical skills to set up these devices.

Just thoroughly read the steps explained below. You only need a flashlight and solar light.

  1. First of all, you have to find an external light source that is more powerful than the light coming from a typical torch, mobile flashlight, or stage light. A flood light will be a good option.
  2. Then you need to mount or place your solar lights closer to your artificial light source. Closer the better.
  3. Let the solar light charge for at least 4 hours. Then it will be enough.

Note: I have to say that this method may not save energy very much. Since you are producing more external power for the flashlight, the overall energy loss will be higher. However, this will be a good method when you do not have sun all day, like in the winter. You can save your solar light batteries with this method.

Types of external light sources you can use for solar light charging

Hand- crank Flashlights

The hand-crank powered the flashlights and it is use dynamo for electricity generation. You can easily recharge them by turning the crank. And also these flashlights can use to recharge your solar lights too.

Hybrid flashlights

Hybrid flashlights are also an ideal option for recharging your solar lights. Because the combination of solar panels and hand-crank improve the efficiency and facilitate recharge with either method.

Rechargeable flashlights

These flashlights consist of a battery and you can again and recharge and use them. You can charge it by connecting it to a USB cable. Then use it as your external light source.

What are the pros and cons of charging solar lights using a flashlight?

Pros

  • Sometimes you can’t access direct sunlight. in that situation, the external flashlight is an excellent method of charging a solar light indoor and keeping them alive, especially in winter.

Cons 

  • Flashlight charging is not an excellent option for charging solar lights due to the higher energy loss in the external light.
  • Time is the main constraint in flashlight charging. You have to wait lots of time to fully recharge your solar lights for better functioning.
  • You can’t use every type of flashlight for charging solar lights. There are some specific spectrums and intensities required to charge the solar lights.

Tips for improving charging efficiency of flashlight charging

  1. Keep the flashlight as much as closer to the solar panel: The solar panel needs direct power to generate electricity. The shorter distance can obtain more energy.  Then it will enhance charging efficiency.
  2. keep the flashlight focused on the solar panel:   To get the maximum from the flashlight, you have to adjust the light to fully touch the solar lights’ solar panels.

Final Thoughts

Solar lights are specifically designed for work and recharge with direct sunlight. But if you haven’t access to direct sunlight, flashlight charging can very useful. But keep in mind you can’t get optimum efficiency through a flashlight.

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