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Dry Cell Instructions

Depending on the kit you have purchased, most of the items below will be included:

  • Dry Cell
  • Constant Current Pulse Width Modulator (PWM) with Liquid Crystal Display.
  • Electrolyte Reservoir
  • Dryer (to trap any water and dry the HHO)
  • Heavy-duty plastic tubing (1/4" inside diameter)
  • Heavy gauge wire for connections between PWM, Battery and Cell
  • Electrolyte (not included with international shipments)
  • Kit parts including elbows, T, electrical connectors, etc.
  • Electronic Fuel-Injection Enhancer, or EFIE (Optional)

24 Volt Systems

Large trucks in the U.S. often operate on 24 volt electrical systems. Many European countries use 24 volt systems as standard for both cars and trucks. If your vehicle uses 24 volts, instead of 12 volts, please see the section titled, "24 Volt Installations" in the PWM Instructions. There is important information about these systems that you must know.

Important Safety Notes

HHO (hydroxy gas) is highly combustible, volatile, and explosive. It is no more dangerous than any other fuel, but only when it is used properly. The most important single element in your installation is to make sure that HHO is only being produced when the engine is actually running. For instance, you don't want HHO being produced when you are sitting in your car with the accessory switch on, listening to your CD player. So the key is to find a circuit that is only on when the engine is actually running. These instructions will tell you how to achieve this product. Just realize the importance of getting your installation done in a way that will achieve this goal.

Other safety points to consider:

  • NO spark or flame should be allowed near HHO gas.
  • All one-way valves must be installed.
  • Do not operate the Dry Cell indoors.
  • Use eye and skin protection when mixing or handling electrolyte.
  • In the event of eye or skin contact with the electrolyte, flush with plain water.
  • Mix and store in heavy-duty plastic containers - keep away from children

Assemble the following items in addition to those provided in the Dry Cell Kit:

  • Voltmeter or multi-meter
  • Basic tools: wire stripper, screwdriver, pliers, etc
  • 1 Gallon steam distilled water for electrolyte (make sure it says "steam distilled")

Assess the space available in the engine compartment. You must find or create space for the following components:

  • Dry Cell
  • Reservoir. Note: the Reservoir should be installed above (i.e., higher than) the Dry Cell to facilitate the flow of electrolyte into the cell.
  • Dryer
  • PWM (see the separate instructions for installing the PWM and Controller/Display)

1. Mount your components

Installation Diagram

Mount your cell, reservoir and dryer. Make sure the reservoir is higher than the cells, as water must feed electrolyte to the cell by gravity.

2. Make the tubing connections

Connect tubing between the cells and the reservoir as shown in the diagram. Notice that the lower fitting on the cell connects to the lower fitting on the reservoir. This is for the flow of electrolyte into the cell. The upper fitting on the cell goes to the upper fitting on the shoulder of the reservoir. This allows the HHO gas to flow to the reservoir, bringing some electrolyte with it. Any electrolyte that is pushed up this tube will drop into the reservoir. The fitting in the lid is used for HHO output. We use a fitting in the lid so that when the vehicle is in motion and the electrolyte is sloshing around in the reservoir, it won't be pushed out and fill up the dryer.

The Drain T shown in the diagram should be routed to a place where you can reach it easily. It is meant to be used when you need to drain the system. You should tighten the nylon nut with a wrench. Finger tight won't be tight enough to prevent leaks. There is a rubber washer in the cap that will allow a seal to be made.

At the air intake for your engine, you will need to drill a hole to fit a 1/4" NPT threaded fitting. You want to drill this hole into one of the plastic air channels that leads to the engine intake. The size of the hole should be 7/16". We provide a threaded elbow that will screw into this hole. Use some clear silicone sealant to ensure that this connection is air tight.

Now you can complete the tubing connections to all the devices as shown in the diagram above. Make your hose-to-fitting joints permanent. We do this with a cable tie. Push the tube onto the fitting as far as it will go. I use a little liquid hand soap on the fitting to make the tube slide on more easily. Then, place the cable tie around the tubing, between the barb and the end of the tubing. Don't put the cable tie directly over the fitting's barb. After cinching it up by hand, use a pair of needle nosed pliers to tighten the cable tie around the hose. Do this by gripping the cable tie close to the joint and twisting with the pliers to get the cable tie tighter. You can tighten in this way until the cable tie breaks off, or you can snip off the excess.

3. Mix your electrolyte and fill the reservoir

It is very important that you use steam distilled water only. Look closely at the label. Filtered water is not good enough. Neither is reverse osmosis. Do not use tap water, mineral water, spring water, or purified water. It must be "steam distilled". The proportion of potassium hydroxide (KOH) to distilled water is approximately 1/2 cup per gallon. However, small adjustments may be necessary. This is for systems with 5 neutral plates between each "hot" plate, which is our standard configuration. This recipe is often a little weaker than needed to reach your desired amperage. That's because it's easier to add a little KOH than to dilute the water in your reservoir.

In freezing climates you may want to add some additional KOH to your mix. KOH lowers the freezing point of water considerably. Your system may run at a much lower duty cycle and may be a bit less efficient. But that's better than having your system freeze and not be able to use it at all. If you put in 31% KOH (by weight), your electrolyte will not freeze until it gets below -65 C (-85 F) degrees F. Most climates won't require more than 28% which is good down to -40 C (-40 F). For other temperatures and concentrations see KOH Freezing Temps.

When filling the Reservoir, keep the electrolyte at least 2" or more from the top. If you drive on bumpy roads you may want to hold the electrolyte level even lower. This is so electrolyte will not get into the HHO gas output hose and fill up the dryer, or worse, find it's way into your engine. Refill the electrolyte when the level gets to within 1" from the bottom.

To replenish the electrolyte, add distilled water only. After many refills, you may find you need to add a bit of KOH to keep the amperage up, but in general, you only use up the water. The KOH stays in the reservoir.

Once per year, you should drain out all the electrolyte from the system and replenish it with all new water and KOH.

For additional potassium hydroxide you should get it from a specialty supplier. If you live in the U.S., we recommend getting it from They sell a 2 lb bottle for $6.95 the last time I checked, and that should last you for years. We sell one pound bottles for your convenience, and include a bottle in our kits, but we don't try to compete with the specialty suppliers.

3a. Defoamer

Add the included pool defoamer to your electrolyte mix. It will not affect the efficiency of the system. The defoamer should last until the next time you drain and refill the reservoir. You can get more from your local hardware store. Here is a link to more information on this important ingredient: Cell Production, Important Data. Go to the bottom of the page for more information on where to find it.

4. Install the PWM

Refer to instructions for installing your PWM: PWM Installation Instructions

5. Install Your Electronic Enhancement

We usually include an EFIE for this purpose. The EFIE we include in our kits was designed and manufactured by us ( The instructions for installing it are posted on our website. You can find them here: Installation Instructions. If you need help with your EFIE install, you can reach us at: We will support you as needed on your installation for both the system and the electronics. We also strongly recommend our Documents Page. It has a wealth of general information about HHO systems, and vehicle electronics that will help you succeed with your project.

If you have a diesel engine, you may need to install a MAP/MAF Enhancer. We supply one with our kits when you specify a diesel vehicle. You can also make one of your own. See this article: A Simple MAP/MAF Enhancer.

Some people choose to use a Flash Chip which connects to the OBD2 port wiring. We have found these to work, but to be less effective than an EFIE or MAP/MAF Enhancer. We have generally found that you should not install both a Flash Chip and other enhancer type as they don't work well together. For best mileage results, use an EFIE on gas vehicles and a MAP/MAF Enhancer on diesel engines.

6. Initializing the system

Now you can start the system and begin making gas. Sometimes the system won't start because the electrolyte didn't to through the tubing and actually fill the cell. When this happens you'll have very low or no amperage draw at all. You can fix this by opening the drain cap and letting the air out of the hose. Use rubber gloves for this, and if you get KOH on your skin, get it washed off it will start to burn. But this should get the electrolyte to flow into the cell and it can start making gas.

Once your gas production is going, it's a good idea to check all hose connections for leaks by applying soapy water using a spray bottle. If there is a leak, bubbles will be immediately evident. Repair all leaks. Also note, that failure to screw down the lid to the reservoir properly can allow your HHO gas to escape. Make it a point to always screw down that lid firmly. Also check for electrolyte leaks by visual inspection after it has run for a while.

Watch the display and you will see the amperage climb up to the amperage set point. Once the amperage comes up to it's set point, it will not go higher. But you'll notice that the duty cycle percentage starts to go lower. This is the PWM controlling the output amperage to maintain its set point. If the duty cycle drops too far, like below 50% or so, then you'll want to dilute your electrolyte. If the amperage never reaches the set point, you'll want to add more KOH.

Before adding KOH, be sure that the electrolyte has actually gotten into the cell. If it has, you will see a steady flow of electrolyte and HHO gas coming out of the cell output hose and going into the reservoir. Lack of any flow is almost always caused by vapor lock in the tubing, where an air bubble is preventing the electrolyte from getting into the cell. In this case you must bleed the air out of the tubing to get the electrolyte flow started. The only other causes of no flow are: 1) No voltage being supplied to the cell, and 2) No electrolyte in the water.

Once your cell is basically operating, you may want to adjust your electrolyte concentration. I usually like to have my electrolyte be strong enough to come up to my target amperage when the engine is cold, but not so strong that the PWM has to start reducing the duty cycle. In fact, if the system is cold, I prefer that I'm just below my target amperage. That way as the system warms up, the amperage will climb to my set point, and the duty cycle will remain fairly high. If the duty cycle is getting too low during operation, such as running below 25% - then you are not going to be getting the best efficiency out of your system. Dilute the electrolyte by adding more distilled water.

If everything is OK up to this point, you are ready to start operating your cell for mileage gains. This is done by making adjustments to your EFIE as covered in the EFIE installation instructions. You will make adjustments to the EFIE between each gas fill up, until you have reached the best possible mileage gains.

We expect you to achieve at least a 25% mileage improvement. If you have mileage results that fall below that, we consider you have a failed system and it's in need of some debug. We have customers that have gotten 50% gains and even more. We feel that 35% is a reasonable expectation. If you are not getting gains like this then something is wrong with your installation, and if the problem is found and handled, you'll get the gains you are looking for.

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