Depending on the size of the engine you wish to run HHO to will determine how many, or what type of cell to run. On smaller engines under 1200 cc a single Wet-Cell generator can supply enough HHO for effective mileage gains. But, with a single jar we do have to keep a closer watch on the heat that is produced during the electrolysis process.
When running our Classic jar style generators in multiples, you're dividing the available current from the vehicles alternator by the number of Generator Cells you wire "in Series". Dividing the voltage in allows easier individual cell temperature control giving us a broader window for the electrolyte solution ratio. You will produce even more HHO, with less heat so that the water doesn't "steam off". While running more than one cell at a time is not absolutely necessary, it does provide that extra margin for error to avoid concentrating the electrolyte ratio through evaporation which can cause this "thermal runaway".
All styles of Hydrogen Generators create heat during the process of electrolysis. The easiest way to reduce heat and increase HHO production as stated above, is to divide the voltage applied to the Cell by using 2 or more Cells and wiring these Cells "in series", or in other words, two or more cells connected in a daisy-chain across the battery. With 2 cells wired "in series", each Cell will get half the voltage from the vehicles electrical system and yet the gas production can be more than double that of a single cell. We like to run all our Cell Systems with either 2 or 3 generators wired "in series", which means that the available 13.8v from the vehicle power source will be divided 2 or 3 times, so even when running a 6-Cell System we prefer to wire 2 sets with 3 cells each "in series", or 3 sets with 2 Cells each “in Series”. The rest of the control over amperage draw is adjusted by the ratio of catalyst in the electrolyte solution. Our Instruction Manual illustrates Wet-Cell System wiring option diagrams and catalyst ratios for the different wiring schemes.
Using a Pulse Width Modulator (PWM) is the most sophisticated way of controlling the amperage draw, but its only drawback for some is affordability. While not overly expensive for the work that it does in keeping your system in check, it can double the price tag of a 2 generator Wet-Cell System. We have sold over 4000 jar cell units without any electronics, so the choice is a matter of convenience.