Alternator power

Google 'horsepower to run alternator':

"An alternator typically takes about 1 HP (horse power) for every 25 amps of power generated. So, a 100 amp alternator will require about 4 HP at full output. Most alternators do not operate at full output for very long."

Many a 180 amp alternators ran on my 5 HP 3,600 RPM bench. Speed must NOT sag. The 15 HP hydraulic bench powered my Niehoff 28 volt 400 amp alternator

745W per HP. An alternator is around 55% efficient.

Thanks everybody. Just what I wanted to know. I was musing about water power rig and batteries for off-grid, and have found LOTS of information and how-tos on internet once I started looking in the right places. Looks very possible, but not for me any longer. I just let TVA do it all for me.

Johno02 wrote: "Would it be practical to use an auto alternator attached to a water power turbine to maintain a 12v battery bank?? Has anyone done it successfully?? To provide some power for an off-grid RV location in particular?

Yes it is possible, and, it has been done, but, for anything other than a science experiment, it is NOT very practical. You would be much better off generating a higher voltage (like 120 Volts) using alternating current when you generate hydro power. Nicola Tesla laughed at Thomas Edison for years because Mr. Edison initially didn't understand "why" either. He did eventually figure it out though.

Chum lee

Google Low Head Hydro

You might just do a bit more of an on line search. Several times I have run into low output water turbines one looked a lot like an electric outboard.

But to answer your first question, 1Hp = 1.3Kw. Automotive alternators are not the most efficient, but they sure are cheap.

Matt

Large frame alternators are much more efficient than small frame units

The Chrysler 4091460 old 120 amp alt is a winner. External teg.