Micro Hydro Turbine
The Micro Hydro Turbine system outputs around 60-110 W all day long. We currently don't have any accurate information on its original efficiency, head, or other characteristics. Please update this section and the micro-hydro page if you know more.
System information
The micro-hydro system uses a pelton wheel turbine connected to a single-phase permanent magnet synchronous brushless generator (seemingly custom built), allowing for efficient output with little to no maintenance required (do grease the bearings now and then please). The output of the motor is fed through a full bridge rectifier (Sensata-Crydom M5060SB400) and directly into the battery. This results in a suboptimal yet reliable charge power of ~100W typical, compared to a theoretical maximum of 200-300W (pending further investigation).
The motor consists of 12 slots on the stator and 6 magnets on the rotor. Maximum open circuit voltage is around 31.3V AC RMS (directly from the motor) at 163 Hz and 40V DC rectified (no load). Motor AC Kv is 196mV/Hz and DC Kv is 255mV/Hz.
The motor terminals were extremely badly corroded until a replacement on 2021/1/28, which significantly boosted output power.
Maintenance and troubleshooting
If you encounter no or low wattage output, the water bucket could be covered with leaves or the micro-hydro's brushless generator could have lost its magnetism. Only a few leaves on the mesh that sits on the bucket can drastically reduce the system's performance. The water bucket next to the water reservoir needs to be cleaned once a week.
Note: We originally believed the generator to be a self-excited asynchronous generator (SEIG), which depends on residual magnetism to begin generating. The following paragraph was written with this assumption:
The brushless generator loses its magnetism if the generator is stopped with a load on the system or spins for a long time while disconnected from the batteries. Therefore, it is recommended to disconnect the wires from the batteries before closing the main valve to stop the generator. If the system doesn't output energy even though it is spinning and connected, try to flash the magnetic field of the generator using the guidelines below.
How to flash the hydro generator
Note: We originally believed the generator to be a self-excited asynchronous generator (SEIG), which depends on residual magnetism to begin generating. The following section was written with this assumption. However, this is not correct! The generator has permanent magnets. For this reason, please ignore this section:
You have to flash the magnetic field of the generator if it loses its magnetic field. Residual magnetism in the generator exciter field allows the generator to build up voltage during start-up. This magnetism is sometimes lost due to shelf time or improper operation, among other reasons. Restoring this residual magnetism is possible and is sometimes referred to as "flashing the exciter field". 1
Step 1 2
Start the generator. Check the circuit breakers. Reset them if they are tripped.
Step 2
Insert the steel rod into the chuck of the corded drill. Tighten the chuck.
Step 3
Insert the other end of the steel rod into the cordless drill. Tighten the chuck.
Step 4
Plug the corded drill into the generator. Make sure both drills are set for forward (clockwise as viewed from the handle) rotation.
Step 5
Hold both drills tightly. Press the trigger switch of the corded drill.
Step 6
Press the trigger switch of the cordless drill, so that it spins the chuck of the corded drill. The corded drill acts as a small generator to feed current into the windings of the larger generator to magnetize the field and force it to start working. When this happens, the corded drill will start fighting against the cordless drill.
Furthermore, we could get a flashing module to automatically flash the generator. Another option is to use a drill to excite the magnetic field again.3