Hello All,
I'm working on an energy harvesting project that uses a stepper motor as a generator to convert rotational kinetic energy to electricity for charging a battery. The battery will be used to power a wireless sensor. The motion of the motor will be intermittent, so I need to extract the most amount of energy each cycle. The drag on the pulley is neglegable due to the size and mass of the system.
I’ve created graphs of the voltage and current output of the motor at various rpm and loading resistances. I've also included a block diagram of the components I'm planning to use.
The stepper motor can output voltages above what the solar charger can handle (30 volts max) at the RPM it will be operating at, so I use a voltage regulator to limit the input voltage to the charge controller. The solar charge controller is used to prevent the battery from being overcharged. The SLA battery is then used to feed the sensor/battery through a switching voltage regulator.
I would like to know if I will need to put a series resistance in line with generator to provide the maximum output to the battery. I don't think that the battery will be discharged very much per day so the charging current will be small. I tried to connect this system to the SLA battery without the charge controller to see if it would charge the battery and it wouldn't output enough voltage without a resistance inline.
I realize that this system is not extremely efficient and these components could be combined into a single board, but I wanted to use robust off the shelf components for this project.
Thanks,
Ed
I'm working on an energy harvesting project that uses a stepper motor as a generator to convert rotational kinetic energy to electricity for charging a battery. The battery will be used to power a wireless sensor. The motion of the motor will be intermittent, so I need to extract the most amount of energy each cycle. The drag on the pulley is neglegable due to the size and mass of the system.
I’ve created graphs of the voltage and current output of the motor at various rpm and loading resistances. I've also included a block diagram of the components I'm planning to use.
The stepper motor can output voltages above what the solar charger can handle (30 volts max) at the RPM it will be operating at, so I use a voltage regulator to limit the input voltage to the charge controller. The solar charge controller is used to prevent the battery from being overcharged. The SLA battery is then used to feed the sensor/battery through a switching voltage regulator.
I would like to know if I will need to put a series resistance in line with generator to provide the maximum output to the battery. I don't think that the battery will be discharged very much per day so the charging current will be small. I tried to connect this system to the SLA battery without the charge controller to see if it would charge the battery and it wouldn't output enough voltage without a resistance inline.
I realize that this system is not extremely efficient and these components could be combined into a single board, but I wanted to use robust off the shelf components for this project.
Thanks,
Ed