A Oxyhydrogen booster is a device that produces small amounts of oxyhydrogen for mixing with another fuel prior to burning it in a internal combustion engine. They are popularly used to decrease costs/km in terms of fuel expenses in vehicles.
Oxyhydrogen boosters derive power from the battery (batteries being present in most IC engines, as they need electricity for vehicle lights, sparks (for igniting the fuel in non-magneto-based IC engines), ...). As the combustion occurs a lot more violently and more heat is generated than what was needed to make the gas, the fuel efficiency of the vehicle goes up.
List of manufacturers
- http://centralvalleyhho.com/ :Produces oxyhydrogen boosters for large vehicles