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Why use a Relay instead of a Switch to power your hydrogen Generator On and Off?

A lot of people have problems understanding why they need a relay to control the On/Off of their hydrogen generator, and how a relay works.

A switch rated at 20 amps can handle up to 20 amps, without over heating. If this switch is on your cars Dashboard, that means the wiring for the switch is behind the dash. If your Battery Voltage is wired to the switch, and the switch is wired to your Hydrogen Generator, that means all of the electrical current (amps) is traveling through the back of your Dashboard. If you make a mistake in choosing the correct wire size to carry the amperage your cell is using, or you choose a switch too small to carry the amperage your cell is using, or you make a mistake and add too much Electrolyte to your cell, the amperage will cause heat -- and the heat can cause damage behind the dash. Your wiring could melt, and you would not know it until it was too late. It is very hard to put a fire out - behind the dashboard. Even if there is no fire, the heat can melt other wiring. So it is just not a good idea to send that much amperage through a switch on your Dashboard.

A safer method is to use a Relay. Put it in the engine compartment. Run your battery voltage to the relay, and come out of the relay and go to the Cell. Then you can use a smaller switch to turn the Relay On and Off. Cars have many relays; relays for Horns, Headlights, Fuel Pumps, Turn Signals, and many other electrical components that draw a lot of amperage from the battery supply. One way or another, these relays are controlled by the Ignition switch. The Ignition Switch is not capable of handling all of that electrical amperage, but it is capable of switching multiple electronics.


How the Relay Operates

  • Terminal 30 is for your 12 volt positive from your battery
  • Terminal 87 is for your 12 volt positive output to your cell
  • Terminals 30 and 87 make contact when the relay gets turned on by 85 and 86

Wire an ignition switch circuit to Terminal 85, and wire 86 to chassis ground.
When you turn on your ignition switch, it puts 12 volts on terminal 85 and creates a magnetic field across the coil. The magnetic field pulls contacts 30 and 87 together. That in turn connects the battery with the cell.

The terminals of these relays are defined as follows:

  • 30 is the common or input voltage to be switched.
  • 87 is the normally open connection (switched voltage output only when the relay is energized).
  • 86 is connected to the ground of the triggering voltage.
  • 85 is connected to the positive 12V of the triggering voltage.

Note: in many cases, the connection of pins 85 and 86 can be interchangeable, but NOT if there is a diode wired across the coil.

A wiring harness makes it easy to just plug in your relays and wire up the wires to whatever you need. It includes all 5, color-coded wires to hook to each of the relay's terminals. You can remove the wires and pins you don't need with the blade of a small screwdriver.



30/40 Amp Relay and Harness.

  "WiringProducts.com (Automotive Relays & Harness) 30-200 amps

  Available from "The Robot Market Place"

These parts are available at many Auto Supply Stores. They are very reliable relays, and easy to wire if you use the harness.

The purpose of the relay is to activate your cell when you turn on your ignition.



80 Amp Relay,  (very reliable)

Your Relay is used to connect your battery voltage to the cell. It needs to be capable of handling all of the amperage your cell uses, and then some.

  • High Current Relays are the most reliable and efficient way to turn on your HHO Cell
  • Compatible with all types of alternators and charging systems
  • Wire it to your ignition switch.
  • Water Resistant black phenolic plastic
  • 100,000 Mechanical Cycle Life

  Available from EBay seller bag-boy

  Available from EBay seller audio-adapters






Page Last Edited - 04/11/2022

    Copyright 2003   All rights reserved.   Revised: 04/03/22.                                             Web Author, David Biggs
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