An electric supercharger is a specific type of supercharger that uses an electrically powered forced-air system that contains an electric motor to pressurize the intake air. By pressurizing the air available to the engine intake system, the air becomes more dense, and is matched with more fuel, producing the increased horsepower to the wheels.[better source needed]
Electric superchargers vs. belt driven
In general true electric superchargers are built for short duration race use. Application is currently limited by energy storage. However, belt driven mechanical superchargers consume some of the power produced by the engine, in particular at low revolutions (see Supercharging versus turbocharging supercharger), while electric superchargers are decoupled from an engine via an oversized energy storage (e.g. several electric accumulators in series).[dubious ] This results in different "somewhat raw" boost supplied during low revolution regime of the engine.
Power supply for electric superchargers
An electric supercharger, if supplied by series of common stock electric accumulators, runs independent of the engine to which it provides its boost. However, electrical energy consumed is often higher (in the range of 100 A e.g. Power of 10 kW = 12V * 833 A) than what a production-line generator (e.g. alternator) of the engine can supply. Larger alternators are therefore fitted to recharge accumulators (often reconnected from serial to parallel circuit) during the engine run without the boost.
The efficiency of an electric supercharger is curbed by several energy conversion losses (alternator for charging), damp energy while charging the accumulators and the compressor providing boost. The losses are in general higher than direct kinematic linkage of intake air compressor to engine crankshaft.
Electric assisted turbochargers
Electric assisted turbochargers are turbochargers employing a coaxial electric motor to overcome the time lag of the exhaust gas driven turbine. The electric motor supports the exhaust gas driven turbine at low-end revolutions to compress enough air into engine's intake, while it can be configured as an alternator to extract energy from the exhaust gas driven turbine at high-end revs, which would otherwise need be bypassed via wastegate and eventually replacing the current mechanically driven alternator. Special consideration need be given to the coaxial electric motor operating in proximity of a hot turbine at very high rotational speed (up to 100 000 rpm).
Electric superchargers as a scam
It is worth noting here that the Internet is flush with fraudsters selling "electric superchargers" for just about anything with an engine through baseless claims and outright lies. Consumers should be extremely cautious when considering such things to ensure they understand the fundamentals of what is being offered and to recognize when they are being misled. Most low cost systems marketed as electric superchargers are not. In simpler terms, the typical inexpensive electric supercharger will not increase the horsepower of an automobile due to the inability of a small fan to produce positive pressure at the necessary flow rate.