Parallel Plates  (Unipolar)
Alternating +  -  +  - creates a parallel circuit. Each plate is wired to the 12 volt battery, or an extended 12 volt connection. The batteries 12 volts can be measured between any two plates that are facing each other. In other words, 12 volts is dropped across each set of plates. The following  examples are parallel plate arrangements; every plate is either positive of negative:

When electrical current (amps) passes between parallel plates, it divides if there are more than one set. For example, If two sets of + - plates are wired to the battery, the electrons have two paths to take; If the plates are all the same size, and spaced the same distance apart, the amperage would be divided  equally by 2; half would travel through one set, and half through the other. So in this example, if 10 amps is being drawn from the battery, 5 amps could be measured passing through each set of plates. I hope you are with me so far because it gets a little more complicated when both sets of plates are equally spaced from each other.

Close observation of + - + - shows three water areas + space - space + space - . I represented "space" as the water areas. If 10 amps of current is being drawn, it would be traveling in 3 paths, thus divided 3 times. So, each set of plates has only 3.333 amps passing through it.

Adding Neutral Plates (Bipolar)
When Neutrals are introduced + space N space  - The same amount of current travels through each water area. Voltage is applied to only the end plates, positive and negative. The neutral plates actually cause a voltage drop. Each neutral cuts the applied voltage in half. It does this because it changes the resistance, and spacing between positive and negative; which in turn changes the electrical pressure between neutral and positive and neutral and negative. If you measure voltage from the positive plate to the negative plate, the reading will be 12 volts of electrical pressure. But if you measure from the neutral plate to either positive or negative, the reading will be 6 volts of electrical pressure. So neutral plates are an effective way of lowering the plate voltage.

In a 12 volt system, using this configuration of one neutral, the voltage drop between two adjacent plates would be 6 volts. You have 2 water areas, 12 volts divided by 2 equals 6 volts. Don't take my word for it, go measure it. It will be there. The following examples should help:

In effect, Neutrals drop the voltage to the plates. Lower voltage means less heat. Ideally 1.25 volts is capable of making the most HHO with the least amount of excess heat. Each Neutral plate has a positive side and a negative, or should I say a more positive side and a more negative side. That is why you can measure a voltage drop between them.

Electrical current, takes the same path as Parallel plates, but it must also pass through the neutrals. Here is an example comparing neutral and parallel:

Using Neutrals creates a Series circuit. +space n space n space -
The following would be a Series Parallel circuit: -NN+NN-
We have 12 volts Negative applied to two plates, and one Positive applied between them, That is a parallel arrangement. Amperage has to paths to take. However there are Neutrals in series between each positive and negative. Thus series parallel.

What does all of this mean! It is all brute force electrolysis. But neutrals allow you to lower the operating voltage to each plate, for better efficiency, yet have the same amount of current passing through each plate. The neutrals can provide additional surface area for HHO production as well as lower the heat.

Dry Cell
There is a trick to making the plates more efficient. You must keep the water from leaking around the edges of the plates. You have to seal the bottom, the sides, and the tops so that current can not find its way through the water, around or under the plates. If it does, the electron flow can bypass the plate surface by jumping across the water anywhere there are sharp or protruding edges. That is Yule Browns theory, which is also suggested by Bob Boyce.

Amperage and Ohms Law
Current flow, in an electrical circuit, is Directly proportional to the applied voltage and Inversely proportional to the circuit resistance. That means, If voltage increases, current flow will increase; as long as Resistance remains the same. If Voltage decreases, current flow will decrease; as long as resistance remains the same. In our cell technology, the water is our resistance and it changes with plate spacing. It directly determines how many amps of current our cell will draw. The closer our plates are, the less water there is between them; the lower our resistance will be. The hotter our water is, the less resistance there will be. The more electrolytes we add, the less resistance there will be. Neutral plates cause more resistance ..... because there is more water between the positive and negative plates, thus we end up adding more quantities of electrolyte in order to get the water to pass electron flow from plate to plate. The type of metals we use for plates also affects resistance, but I will not go there right now.


Parallel (Unipolar) vs. Series  (Bipolar)
Both use brute force electrolysis. Both can be configured to produce large or small quantities of HHO. Both can be configured to reduce heat. Both can be configured efficiently. Stan Meyer used high voltage and low current, produced by special electronics, along with Tubes for plates, configured in a parallel arrangement. He believed that tubes produce 2.75 times more HHO than flat plates. Bob Boyce uses Series configurations. He uses large numbers of neutral plates to reduce high voltage to 3 volts per water area between plates, to produce large quantities of HHO, without special electronics.

The verdict; which is better
It all boils down to the power source. What do you have? How can you best use it? How much room do you have for a Cell (Hydrogen Oxygen Generator)? Do you make short commutes, long trips, or both? In most cases, the Series and Series Parallel Dry Cells are used the most in automobiles. The reason.... a low voltage 13.5 Alternator powers the electronics. If you have the knowledge, and the finances, to use high voltage DC to AC Inverters.... and you have the room to accommodate the hardware....and the electronics....you can...I say can....build a system large enough to ...Run your vehicle on Water. Stan Meyer did it; Bob Boyce says he did it and the men in Black made him stop; and Fast Freddy; Frederic Woods, well he is not nicknamed Fast for nothing.