Build Your Own Salt Water Fuel Cell Car

By Ryan Winters – Jameco Product Manager

You read that right! This is the first salt water fuel cell car we've ever seen and with a price under $15.00, how can you resist adding this to your next order? You won't be able to drive this bad boy, but it is a project that packs both fun and education into one kit. Read ahead, and I'll take you through my experience with OWI's salt water fuel cell car kit. Fuel Cell Inspiration As soon as I read the name of the kit, I was intrigued. Apparently, magnesium + saltwater + air = electricity. This kit also has to be one of the easiest to put together; it is literally almost a "snap." This is a great classroom project for learning about different fuel cell technologies and the young scientists can even test different ratios of salt to water to see which mixture yields the greatest efficiency.

Salt Water Fuel Cell Concept

A fuel cell is an electrochemical cell that converts energy from a fuel into electrical energy. Fuel cells can operate continuously as long as the necessary reactant and oxidant flows are maintained. In this cell, magnesium is the anode, the porous carbon sheet (air) is the cathode, and saltwater is the electrolyte. This is known as an air-depolarizing type of battery. During chemical reactions, alkaline earth metals (magnesium) lose two electrons. Elementary halogens such as chlorine, which can be found in ordinary table salt (NaCl), are also relatively reactive. Unlike the alkaline earth metals, the halogens tend to gain electrons. These are known as oxidizing agents because they remove electrons from other elements.

The saltwater slowly dissolves the magnesium sheet to produce hydrogen ions that migrate to the carbon cathode, thus creating an electrical current. The carbon surface would almost immediately become blocked, or polarized, by the hydrogen except that the carbon is porous. Air diffuses down through the carbon and yields oxygen that combines with the hydrogen to form water, permitting the electrical effect to continue.

Fuel Cell Car Build

As always make sure all of the pieces are included. The instructions are very easy to follow, and they clearly list components, quantity, and color if applicable. The directions call for a screwdriver, but you will not need it for putting the car together. The screwdriver comes into play to scratch any oxidization off the connector tab and the magnesium sheet. Salt water is known for being corrosive, but where material is lost, energy is gained.

You may use diagonal cutters or a utility knife to free the plastic parts from their holder. Or you can use the method I use, which I like to call the twist method to free the pieces. Either way you will still need some type of blade or sandpaper to remove the nubs where the pieces were held in place. This is especially important for the wheel pieces. You want them to be round and smooth so the wheels can roll freely.

Assemble the hubs into the wheels. The rear wheels are a little bigger than the front wheels, so make sure you assemble them correctly. Press the rear wheels onto the round shaft that is the axle, and then snap the axle into the car from the underside until you hear a "click". Press the front wheels onto the shaft that has the purple gear already installed. There is only one way to install the front axle because of the placement of the gear. The wheels should come close to being flush with the side of the car, so if they're not, the wheels may need to be pressed onto the axle a little more. I pushed both wheels onto the axle just enough so they wouldn't fall off, then I placed one wheel on the table and pushed straight down on the other wheel while being careful not to press too hard, or the axle could bend.


Once you have both axles installed, flip the car over and locate the motor and the tiny yellow Pinion Gear. Press the pinion gear onto the shaft of the motor. Then secure the motor into the car as shown in the directions, and slide the connector tabs into the slots making sure red is on the left and black is on the right. Install the cover onto the car, and it's almost ready to roll.

The components have to be layered in the correct sequence and position, or the car will not work. The directions are simple enough. Start with the spoiler-looking base. Place the Air Cathode (black side up) onto the base. Place a piece of the non-woven fabric on top of the air cathode. Then place a magnesium sheet on top of the fabric piece, and make sure the tab of the magnesium sheet is not on the same side as the air cathode. Place the cover on top of the magnesium strip, and simply slide it into the slot in the back of the car. The car is now assembled, and you can make a batch of salty fuel.

Brain Power

How much salt is right? Well, the directions suggest one part salt to four parts water will be the most efficient, so that is what I did. Sure enough, the car's wheels were spinning before I could get it onto the ground. The car didn't exactly steer itself straight, but hey, the thing's powered by salt water! You could build a track similar to slot cars to keep them in a line, and then you could race your friends to see whose car has the better mix.

Apparently, any percentage ratio between 20% and 99% salt water is workable. There lies the challenge. Does a saltier mixture make the car run faster or longer? Why would a percentage ratio of less than 20% not be favorable? Maybe even more importantly, what reaction is happening inside to make the electricity? Find out for yourself.

Via: Ryan Winters – Jameco Product Manager http://www.jameco.com/Jameco/content/saltwater.html