- #1
ChuckStr
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So I'm working on a senior design project and was trying to use a DC motor to charge a battery. The point is to allow for quick use to charge a phone or a laptop in circumstances where you need a quick charge. We have lead-acid batteries connected in series and parallel to give us:
14,000mAh with an output of 13.2V and 15.2A
I was wondering what specifications we would need on the DC motor to allow for adequate charging. I'm a mechanical engineer and much of this is beyond my basic knowledge.
From my understanding, correct me if I'm wrong please:
We need a voltage of at least 13.2V coming out of the motor, not its rating, to begin charging and the current needs to be 1/10 the total capacitance to charge in 10 hours. If the DC motor were to be connected to a crank to spin the motor we would need to match the rated RPM's to produce the rated current and voltage of the motor (ignore efficiency for the moment). If the motor is geared so that the crank's desired RPM's were 60 then the torque required to turn the motor would also increase. I'm not sure exactly what torque is considered easy to hand crank but I assume anything less than 8ft-lbs would be decent.
What kind of DC Motor (Brushless, PM Brushless, etc), what Voltage and Current does the Motor's rating need to be to allow for ANY charging, and what ratings would be best for charging?
We're having the battery connected through regular switches to prevent unnecessary discharge and have a switching regulator connected to a USB Outlet to allow for USB charging. We also have a 300W inverter to allow for traditional wall outlet charging.
Side Note: Since the motor will be hooked up directly to the battery it is my understanding that a zener diode(help please?) needs to be wired into prevent from the motor to spin when not cranking. Input on anything is greatly appreciated. If any of this is overkill, inefficient, not enough, or just wrong please correct me.
Thank you, Chuck
14,000mAh with an output of 13.2V and 15.2A
I was wondering what specifications we would need on the DC motor to allow for adequate charging. I'm a mechanical engineer and much of this is beyond my basic knowledge.
From my understanding, correct me if I'm wrong please:
We need a voltage of at least 13.2V coming out of the motor, not its rating, to begin charging and the current needs to be 1/10 the total capacitance to charge in 10 hours. If the DC motor were to be connected to a crank to spin the motor we would need to match the rated RPM's to produce the rated current and voltage of the motor (ignore efficiency for the moment). If the motor is geared so that the crank's desired RPM's were 60 then the torque required to turn the motor would also increase. I'm not sure exactly what torque is considered easy to hand crank but I assume anything less than 8ft-lbs would be decent.
What kind of DC Motor (Brushless, PM Brushless, etc), what Voltage and Current does the Motor's rating need to be to allow for ANY charging, and what ratings would be best for charging?
We're having the battery connected through regular switches to prevent unnecessary discharge and have a switching regulator connected to a USB Outlet to allow for USB charging. We also have a 300W inverter to allow for traditional wall outlet charging.
Side Note: Since the motor will be hooked up directly to the battery it is my understanding that a zener diode(help please?) needs to be wired into prevent from the motor to spin when not cranking. Input on anything is greatly appreciated. If any of this is overkill, inefficient, not enough, or just wrong please correct me.
Thank you, Chuck