I was thinking about using PMA as alternator for producing 12V or 24V. The problems are a few with PMA:
1. Most PMAs are modified car alternators.
2. I couldn't find a good professionally designed PMA under $500 USD
3. People who build PMAs make performance claims without any proof, making this claims just a blah blah blah. As a matter of fact most power, voltage, rpm etc claims are pure BS in most cases.
4. Even considering all above and finding some "good" ones the power output is very limited.
5. PMAs produce unregulated power and in order to keep power in usable and efficient range (volts, amps) engine speed must be controlled very closely.
So, after some research I decided to find a good reliable high perfomance high efficiency car alternator. I was lucky enough and found this guy:
American Power Systems 55i 200ACT 28J Alternator T33418 | eBay
It is made by American Power Systems and the model is 55i-200ACT-28J
Here some specs of this great unit:
The APS Brute series alternator delivers 6.3 kW of clean, regulated DC power in a ruggedly built chassis designed to meet the rigors of military use. This alternator is designed to meet military standards and multiple units can be paralleled for additional power.
Rated Power: 6.3 kW
Rated Voltage: 28 VDC nominal
Output Current: 225a nominal
Charge voltage setpoint: 28.2 V
Recommeded Pulley Ratio: 2:5
Output at engine idle see curve
Plug Interface: Direct OE compatible
Love this one:
Efficiency: 87% typical.
Not bad compare to 55% efficiency of a regular car alternator.
Mount: Wide Pad or J180
Weight: 35 lbs.
Cooling: External fans
And after all I paid $ 400 USD for it which is not bad at all for a new alternator like this....