overheating problem

[pook7one]

I have a 2 gallon basically an old inline water filter, really heavy duty with a 9 plate cell hho generator. 3 positives, 2 neg and 4 neutral plates. i used it for the 1st time this morning, and it got extremely hot almost to boiling. my question is, if i remove it from the engine compartment, and put it where it wouldnt get help from the engine getting hot, will it stay much cooler?, or is there a better way?

[Helz_McFugly]

you may have to much electrolytes in your water. 110 to 150 seems to be the norm in my cell. I have in the past put to much KOH in my water and it boiled.

[richard_lyew]

you may have to much electrolytes in your water. 110 to 150 seems to be the norm in my cell. I have in the past put to much KOH in my water and it boiled.

good call but if he drop the level of electrolyte in the mixture his production will drop too, this was one of my biggest problem until i start cooling the mixture.

[Roland Jacques]

I have a 2 gallon basically an old inline water filter, really heavy duty with a 9 plate cell hho generator. 3 positives, 2 neg and 4 neutral plates. i used it for the 1st time this morning, and it got extremely hot almost to boiling. my question is, if i remove it from the engine compartment, and put it where it wouldnt get help from the engine getting hot, will it stay much cooler?, or is there a better way?


It sounds like you have to much voltage per cell (not enough neutral plate in between + & -

With 9 plates and 12/13.5 volts your cell should look like this -nnn+nnn- even that's would run hot. Try to have at least 4 neutral plate for a 13 volt system. That will give about 2.6 volts per gap. 5 neutrals should be even better -nnnnn+.

[Philldpapill]

What electrolytes do, is provide a better means for electrons to flow. When electrons DO flow, even when they don't "want" to(resistivity), they usually end up colliding into other atoms, like a drunken irishman(no offense anyone!). Ideally, you want the water to be saturated with electrolyte in order for it to provide as MUCH conductivity as possible. When there is alot of resistance in the water, you need a higher voltage to get the current flowing that you want. This higher voltage results in excessive heat produced.

What you SHOULD be doing, is regulating the voltage to your cell. This is pretty hard to do with all those cheap PWM modules out there. However, it CAN be done by putting a hefty capacitor in parallel with your cell. What this does, is it kind of "buffers" the current into the cell, resulting in a smoother(and lower) voltage delivered to the HHO cell. In electrical terms, it's kind of like a "low pass filter".

If you want, I'll get on Mouser.com and find a good capacitor for you. It should only be about $10. What kind of peak currents are you seeing? What voltage?

BTW, in reality EVERYONE should be using a good capacitor on their PWM units... Less heat this way.

[Roland Jacques]

Hi Phil

I dont understand how the capacitor lowers the voltage, how much lowering are you talking? how big of a capacitor would you recommend?



If he has 9 plates the way he describes I dont think a PMW would help.

+n-n+n-n+. thats 6.5 volts per gap, effectively more of a heater than a HHO maker

[Philldpapill]

With the normal PWM people use, it isn't REALLY Pulse Width Modulation... Well, it is, but it doesn't achieve the usual goal... The main reason we use PWM for HHO cells, is to be able to take control of the RMS current to the cell. If too much current goes through the cell, it will eventually get hot and boil.

Normally, PWM is usually used as a type of "digital to analog conversion"... Fancy words that just means turning a digital value of something, and turning it into an analog value. In this case, the "digital value" of the current, is, at any given instant, either fully on, or fully off - no in between. So, what we do in electronics to create an analog signal, say 2.3V, rather than either 0V or 5V(whatever the two states are), is to use PWM.

I hope this analogy helps to visualize what is going on. Picture a water tower... The purpose of a water tower is to hold water way up in the air, so that we have water pressure at the sink, or shower. There is a pump that pumps the water up there. One might ask, "why not just use the pump to provide pressurized water to us, and cut out the water tower all together?". It's a fair question. The reason: The pump would have to run continuously to provide pressurized water to us - Not good for the pump. So, what we do, is we watch the water level in the water tower and turn the pump on when the water level gets a bit too low, and off when it finishes filing back up. The average person has no idea when the pump is running, or when the water tower is low - it provides a nice even water pressure all the time. The pump cycling on and off is the type of PWM most HHO'ers use, but very few use the pump AND water tower.

Expanding on that: what if we had a really small bucket and a small pump. There is a hole in the bucket, and we are cycling the pump on and off at a 50% duty cycle. If we use the small bucket, we will REALLY notice a change in the water level whenever the pump cycles on/off. If we get a bigger bucket, the water level in the bucket doesn't change very much at all. The volume of the bucket smoothes out how much the water level changes. In electrical analog, the bucket or tower is the capacitor in this circuit. If we just cycle a pump on and off or like switching the current on/off, the water level changes drastically. However, if we put a capacitor in there, the voltage stays fairly constant across the load - like the water level does.


One other note for clarification: Not sure if everyone realizes it, but the RATE at which the water flows out of the bucket is related to how high the water level is. The higher the water level, the faster water escapes, and the faster the water level drops... That analogy and concept is the reason why using PWM can regulate the average voltage across a load(using a capacitor). The amount of current leaving the capacitor into the load, is proportional to the voltage on the capacitor... So, it's the same - the higher the voltage, the faster the voltage drops... Using PWM, the votlage on the capacitor will reach a fairly steady value under a steady PWM duty cycle.

Make sense? All in all, using a capacitor results in a lower power loss since we don't have BURSTS of current into the cell each time the PWM unit switches on. Remember: Power = Current*Current*Resistance, so the higher peak currents result in higher power loss and more heat. Bottom line...


EDIT: Oops! All that and I didn't even answer your question, Roland. Using a capacitor allows you to vary the voltage from 0V, all the way up to whatever your supply can handle. 0% duty cycle = 0V, 100% duty cycle = Voltage supplied... 50% duty cycle = Voltage supplied / 2. Those figures are just approximate, and in reality, it's a non linear relationship... At some point, the voltage across the load will remain fairly constant... This is the threshold voltage for electrolysis to begin, and if your voltage isn't high enough, very little current will flow. If no current is flowing INTO the cell, the voltage on the capacitor will remain the same, until the PWM comes on and dumps a bit more charge into the cap, raising the voltage, thereby raising the voltage above the threshold, allowing current to flow until the cap voltage goes below threshold and stops, etc. etc. etc.... Steady state!

[Roland Jacques]

Wow, thanks for such a clear explanation. i now even understand caps and PMWs even better.

So you meant that the capacitor for the PMW would go after the PMW, before the electrolyzer. That i can understand. I thought you meant before the PMW my bad.

[Philldpapill]

Yeah, sorry, it shares common connections with the cell. Preferably closer(in wiring) to the cell, than the PWM, but it doesn't matter toooo much. Also, when using a cap, a higher frequency is a little better. Just be sure the cap is RATED for the current you are using. Otherwise, the cap will heat up and KABOOM.

Actually, if anyone wants to discuss this any further, i.e. efficient power conversion, I can start a thread about it. You can use some heavy inductors and diodes and a capacitor to make a VERY smooth supply is very efficient. That Power Supply I'm making involves this, but has more complicated circuitry to make a "Buck" Converter... Steps down voltage, steps up current, kind of like a transformer.