I actually used to work at an auto parts store for a while and worked with alternators a little bit. I'm no expert by any means, but have a little experience with them. If you've ever tried to spin the wheel on an alternator by hand you can easily tell a difference between an alternator that is rated for high amp output compared to a lower amp style. If you have your engine running and you have someone inside the vehicle turn on accessories, you can (most of the time) actually hear the alternator make a little more of a whirring noise. Q-Hack put it perfectly, "Since the alternator is effectively a coil of wire spinning through a magnetic field, the more amperage you pull the greater the electromagnetic field the harder it is to spin the coil of wire through it."
All alternators have a range that they are designed to work in. The more time to spend in the higher range, the less life your alternator will have.
With all the accessories that are put on vehicles today, (additional lighting, larger stereo systems, etc) I would think a hydrogen generator wouldn't be much of a concern as long as you don't go crazy.
Give a man a match, and he’ll be warm for a minute, but set him on fire, and he’ll be warm for the rest of his life.
2000 Pontiac Grand Prix GTP 3.8L SII S/C'd
15%-20% MPG increase at 1.5 Amps
2000 Jeep Grand Cherokee Limited 4.7L V8
No gains.