I’m new here, just started looking into the whole concept. I have lots of credentials and experience in electronics, mechanics, and physics. Just using the accessory “Key on” position from the fuse box in my opinion is not thought out well… example, the cell will still get power if the engine stalls or the key is flipped to the accessory position, say someone is waiting in your vehicle and wants to listen to the radio while you run into a store.

I suggest using a simple frequency to voltage converter, and hooking it up to the tachometer leads… you can make something like this quite easily using a “555″ ic timer, a switching transistor, and a heavy duty lighting relay. You’d adjust the timer circuit to watch for engine rmp’s… say 500 rpms for example, surley that’s way beyond the starter’s cranking speed. Once the timer sees roughly 500 rpm’s: the 555’s output tells the switching transistor to fire, which sends a strong signal to the headlight relay… voila a safe way to energize and deactivate the power going to your cells. An ic comparator can probably be used as well.

Just monitoring battery voltage would be less accurate, as when you first power the engine off- its common for a battery to be slightly overcharged. I’ll ponder this more, if there’s enough interest: I can prototype a circuit, also I’ll see if a battery voltage sensing circuit could be viable, as it’d be the simplest to set up.

Basically, a fully charged battery is 12.6 volts with the engine off, and should be about 13.8 volts with the engine running. If I set a sensor circuit up to shut down below say 13.5 volts, then it may be an acceptable (safe) way to switch the cell on and off.

I have some simple ideas to stabilize some of the heating problems in the cell as well. First off, consider the mass of the stainless electrodes… the greater the surface area of the electrodes- the more heat you’ll transfer into the fliud (which is what you want), then you need to stabilize the temperature of the fliud (cool it) you could simply coil some copper tubing around the inside of the cell’s jar, then use the engines air-intake to create suction throught the tubing. The other end of the tubing is simply an air inlet vent… the outside air is drawn through the copper cooling coil immersed in the cell jar thus stabilizing the fluid’s temperature.

Thanks… Brad…

To all: Another design I saw and liked had a long rod which was connected to the outside world on top but went to the bottom of the plates so that the connection to the plates was underwater, no chance of a spark due to a corroded or loose wire connection in an explosive environment.

Having to endure a few 5 degree nights here in the DC area we surely will have to address an anti-freezing agent into our designs so that those in cold climates can say “See ya!” to the oil goons.

Agustin: We applaud your efforts. Will you be sharing your info with the rest of us trying to save our planet or will you be selling it? Is the PCB inside the unit in the HHO environment? If so, won’t that lead to corrosion-related premature failures? So what kind of production numbers, liters per minute, are you seeing with your PWM’s and your “2 inch & 3 inch designs” with how many amps drawn?

Thank you