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This isn’t exactly true. In fact the alternator DOES produce “excess power”. It produces MORE energy that is used in MOST vehicles to 1) power lights, radios and so forth and 2) keep the battery charged completely. (Not all cars have high duty alternators).

My understanding of alternators is that they produce what is demanded of them. If there is no load on the alternator, nothing connected, then the only mechanical demand from it to the engine is to overcome the friction of spinning it. Any additional mechanical demand is the direct result of the output current demanded of it, with consideration for output efficiency.

An alternator can produce more than is typically demanded; there is excess capacity. But that's not the same as excess production or output.

So any increase in electrical demand on the alternator will just result in extra mechanical demand, and it takes more mechanical power going in than electrical power going out because alternators are not 100% efficient. That, plus the fact that electrolysis is not 100% efficient, that is, you won't get the same hydrogen energy out of the process as the electrical energy you put into it, means that the Mechanical (engine) --> ( < 100% efficient) --> Electrical (alternator) --> ( < 100% efficient) --> Chemical (Hydrogen electrolysis) chain cannot result in a net gain.

I believe the author is correct.

First, there’s no such thing as “100% efficiency” - so I am not saying the author doesn’t know what he’s talking about. I question the author’s remarks regarding certain things I’ve already laid out.

And no, you and several others have made the comment that “alternators don’t” do anything unless a load is demanded of them.

Technically... unless there is a “complete circuit” - which in very simple terms is a complete path for current flow, a resistance and a potential difference of electrons (that would be a battery or another voltage source) there is NO demand, therefore there is only “potential energy”.

This means that basically ANY generator that is turning (AC, DC doesn’t matter) has a set of coil windings that being moved in a stationary magnetic field, or a moving magnetic field around stationary coils) whether CONNECTED to a circuit or NOT is a “potential energy source”.

If there is a path - which in a running engine, there IS (at the very least to power the charging circuits for the battery) current flow. More current will flow as the load increases. (This means as the RESISTANCE DROPS more CURRENT flows - which means more electrons flow in the circuit.)

The fact is that generators/alternators in cars are capable of producing much more current in most cases than they actually produce.

In proper engineering you always over design a circuit... so if your circuit will use say, 1 Amp, you design the circuit to have devices that can handle roughly double that so you have little chance of overheating components etc.

(Using heavier wire than the minimum necessary is good practice. Using 2 watt resistors in a circuit instead of the 1 w resistors that are all you need is good practice. Putting in an alternator capable of handling EVERYTHING in the car plus extra items that might be added on - as in my case, radio systems and a different stereo system than came iwth the jeep... is GOOD practice)