have several question about diesel alternator. First of all i want build micro hydro system using diesel alternator. That means i just take the alternator and using water to rotate the turbine and the alternator will produce the power. Do you think this system is possible to do? Before this i use the car alternator, and the problem is before alternator connected to the battery i get about 3000 RPM, but when i connect the alternator to the battery and field current occur, the RPM dropped to 500 RPM. So the alternator can't produce the current. So i want try using diesel alternator. Since we know diesel alternator power output in AC, so no field current needed. If i get around 3000 RPM, whether diesel alternator produce the power? Or it same with car alternator.
I have always wanted to try to use hydroelectric power using a car alternator. I believe it can be done through the right ratio in a pulley system.
all alternators produce alternating current---by definition--duh it is then rectified by (usually internally mounted) diodes you are loading your system with a partially discharged battery and the voltage that the regulator is set to is trying to charge the battery at a rate greater than the mechanical power (turbine + water) can supply thus it slows down until the demand matches the supply if you left the system until the battery voltage increases you would find that the system would turn faster until the voltages matched each other and it would be doing 3000 rpm
When you connect the battery, to the automotive alternator, you are making it operational, by activating the rotating magnetic field. It is slowing down, because it is now supplying power to its own field, as well as charging the battery. As the automotive alternator charges the battery, it may pickup speed over time. However, considering the drastic RPM drop when you connected the battery, I believe the power provided by the turbine is inadequate. It may be to small for the application, or the head provided by your water source is too low. Switching to a generator, designed to provide domestic power, i.e., 120/240 VAC 50/60 Hz, will greatly complicate your power-plant. Such devices must be rotated at their design speed, in order to produce power at the correct voltage and frequency. In contrast, automotive type alternators, along with their voltage regulators, whether they are internal or external, are designed to provide constant DC voltage over a wide range of shaft speed. Frequency is not an issue, because these three phase, alternating current generators, output direct current, via full-wave, solid state, internal rectification. Furthermore, any generator requires field current, unless it is a small generator, with exceptionally powerful permanent magnets. I recommend you stay with the automotive generator, along with a large deep cycle battery, and use an inverter to get alternating current. The battery, will be helpful in handling surges, or temporary loads, exceeding the automotive alternator's capacity.
