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Hand splashing through blue water

Water-powered flashlights and how they work.

Survivalwiz isn’t paid or sponsored by any companies named in this article.


One of the most common modern-day backpacking or camping dilemmas we often face is how to keep your life-saving electronics like your phone, power bank, or light source charged, especially during more extended camping or backpacking trips.


There are already a few solutions on the market today in the form of solar-powered electronics like flashlights and power banks. Still, these rely solely on the weather conditions to recharge, and if you are hiking through the deep forest or in off-grid areas, they won’t be able to renew, which can become a severe problem in emergencies.

Luckily, innovative companies like H2OnlyBattery and Hydra have developed water-activated fuel cells as a greener alternative to regular Alkaline or Lithium batteries. The fuel cells give power to both Flashlights and power banks without requiring any battery or leaving any waste.

But how do water-powered Flashlights work?

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Water powered flashlights on todays market.

Regarding water-charged flashlights, there are two major players on the market, Hydra-Light, and H2OnlyBattery, which both produce and sell different types of water-driven flashlights. There are some differences in the types of products the companies have in their assortment, which I will explain here:

The Hydra-Light 2 in 1 flashlight

Hydra-light is an Australian firm that produces flashlights, lanterns, and other charging products, all powered by water. Their most famous product is their Hydralight 2-1 Flashlight from 2019, which uses water-activated HydraCells instead of regular batteries. 

According to the manufacturer, these fuel cells have up to a 600-hour run time on a single charge, longer than the average AA alkaline batteries, and a shelf life of up to 25 years. Some Hydra-lights products also use a secondary power source like a solar panel or rechargeable batteries to enable faster recharging. (1)

How the Hydra Flashlight works:

The flashlights Hydra-cells can be charged by following these four easy steps:

Step one: Unscrew the bottom of the flashlight and remove the Fuel cell.

Step two: Remove the plastic from the cell and immerse it in water for 10 seconds.

Step three: Shake out any excess water from the fuel cell.

Step four: Insert the fuel cell and turn on the Hydra light.


Easy, right? and the intelligent thing is that it runs on any type of water, including distilled and salt water; this means you can quickly recharge on the go and even with rainwater, so no more worrying about bringing spare batteries next time you are out in nature for multiple days during your next backpack or camping trip.

H2OnlyBattery FL-103

H2OnlyBattery is a company based in Greece which has produced water-powered Flashlights and power banks since 2016. Their main goal is to make flashlights for emergencies, disasters, and general applications.

Like Hydra, H2OnlyBattery also uses a self-developed fuel cell that can produce energy from water and power small electronic devices like flashlights and power banks. Their latest model, the FL-103, has a total operation time of 350 hours and a Run Time of a maximum of 60 hours on a single charge, according to the manufacturer. (2)

How the H2OnlyBattery flashlights work.

The Process of recharging the H2OnlyBattery flashlights is similar to the Hydra-Light, just a bit simpler with three steps.

Step one: Find some water or liquid to submerge the flashlight.

Step two: submerge the light until you reach the immerging limit line, and keep it there for a minimum of 5 seconds.

Step three: shake out any excess water, and turn on the flashlight.

And that’s it! The flashlight is fully recharged; it doesn’t get easier than that; all their flashlights recharge similarly. As mentioned before, the H2OnlyBattery fuel cell operates with any liquid, making it easy to restore even in emergencies and helpful for more general applications.

Are water- driven flashlights worth buying?

Even though water-powered flashlights are a genius piece of technology and valuable in many situations you may encounter when out in the outdoors or in your day-to-day life, they still have some shortages in their features and specs, which can be limiting in some applications. 

Ultimately, it comes down to personal preference and what you expect of a flashlight. I won’t tell you if a water-driven flashlight is worth buying, but I will help you decide by enlisting the different pros and cons of the technology.


Water-activated fuel cells are still a relatively new technology and are a long way from genuinely replacing batteries in all our electronics; when that is said, they have some significant pros and potential, making them very interesting to keep an eye on.


A reliable light source

If you plan to go on a more extended hiking or backpacking trip where you won’t have a reliable grid connection, having a water-powered flashlight or power bank in your emergency kit could be helpful if your other electronics fail and may be worth considering.

Because the products are water-powered, they can be used as a reliable light source for those living in rural areas without a stable grid connection or in emergencies, natural disasters, or conflict zones because of their long Run Time, quick recharge time, and durable design.

Closeup of hands holding batteries



The Environmental Impact of single-use batteries.

 The Environmental protection agency estimates that approximately 3 billion batteries are thrown away each year in the US alone. With the current increase in the earth’s population, this number may rise to 28 billion batteries annually thrown away globally. (3)

Batteries often contain different chemicals and metals like mercury, lead, silver,  and nickel, damaging your health or the environment if the battery isn’t discarded correctly after its use. (4)

This linear way of using our valuable resources isn’t sustainable in the longer run, and that’s what innovative products like the FL-103 and the Hydra-Light, are trying to help solve 


Even though water-activated fuel cells are an impressive technology, which might be capable of replacing batteries in the future, they still have some significant limits worth mentioning that need to be overcome if they are to be considered a genuine challenger to batteries.

Limited brightness

One major con of water-powered flashlights is their limited output and brightness compared to battery-driven flashlights. Some of the brightest water-powered flashlight on today’s market only has an output of 100 lumens or less, which is nowhere near enough for even basic indoor applications or for illuminating a tent or your surroundings when walking at night.  

Dull flashlight by steve johnson.

The limited lifetime of water-driven fuel cells.

One of the most significant flaws of water-powered flashlights is that, eventually, the fuel cells will be depleted and stop working, and you need to find a replacement fuel cell. Unfortunately, the availability of Fuel cells is limited, and, therefore, almost impossible to buy a replacement fuel cell, which means it might be necessary to buy an entire new flashlight, which will be expensive in the long run. 

For example, The Hydra-Light will work for three total charges with 100 hours of run time before the fuel cell is depleted and needs to be replaced. So if you are looking for a long-lasting flashlight, you should consider looking for a regular battery-driven flashlight instead.

The lack of features and cheap design of the flashlights.

Due to the size of the fuel cell required to power a regular flashlight, water-powered flashlights tend to be much more prominent in size than standard battery-driven lights. They also have fewer features than ordinary flashlights, which can be limiting in surtain situations.

Most water-powered flashlight cost between 30$-50$, like the Hydra-light, and when you compare the features you get and the quality of the design compared to battery-driven lights, the water-powered flashlights don’t stand a chance. It is a remarkable piece of technology, and if you are a gear freak like me, it’s a fascinating flashlight to have in your collection, but it’s mostly just for show.   


The future of water powered flashlights

Water-powered flashlights still have considerable potential and might be a good tender to replace regular batteries in the future. Still, the limits in the current technology are too huge to ignore. The output limits of the fuel cells and the lousy design of the water-powered flashlights on today’s market don’t live up to the expectations consumers have of their flashlights.

The price of water powered flashlight compared to the features you get, in my opinion, is not worth it in the long run. Water-driven flashlights are a cool gadget if you need to impress your friends or spouse, but they aren’t valuable for most real-life situations due to their lack of brightness and overall features. So, in conclusion, if you are looking for a flashlight for hiking, indoor, camping, or tactical uses, you must stick with the good old regular lithium battery flashlights for now.

Patrick. D. Bayless

Patrick. D. Bayless

The founder and main writer on Survivalwiz.


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