Reverse battery protection for a trolling motor
View Patent ↗A trolling motor having reverse battery protection such that an inadvertent reversal of the battery leads, as when connecting the trolling motor to a battery, will not cause unwanted operation of the trolling motor or damage to the trolling motor circuitry. The reverse battery protection includes a field effect transistor connected in series between one of the battery leads and the motor. The gate terminal of the transistor is in communication with the other battery lead such that, when the battery leads are properly connected to a battery, the transistor is driven to its conducting state and, when the battery leads are reversed, the transistor is driven to its non-conducting state.
1. A trolling motor having reverse battery protection comprising:
an electric motor;
a first battery lead for connecting the trolling motor to a first terminal of a battery;
a second battery lead for connecting the trolling motor to a second terminal of a battery;
a field effect transistor having a source connection, a drain connection, and a gate connection, said drain connection connected to said first battery lead, said source connection in electrical communication with said electric motor, and said gate connection in communication with said second battery lead such that when said first battery lead is connected to said first battery terminal and said second battery lead is connected to said second battery terminal, said field effect transistor will be driven to a conductive state, and when said first battery lead is connected to said second battery terminal and said second battery lead is connected to said first battery terminal, said field effect transistor will be driven to a non-conductive state.
2. The trolling motor of claim 1 wherein said field effect transistor further includes an intrinsic diode having an anode and a cathode, said anode connected to said source connection and said cathode connected to said drain connection.
3. The trolling motor of claim 1 wherein said field effect transistor is an n-channel device and wherein said first battery terminal is a negative battery terminal.
4. The trolling motor of claim 1 , wherein the trolling motor includes a current limit protection, the trolling motor further comprising a pulse width modulated motor controller, said motor controller comprising:
a current sense input for measuring the voltage across said field effect transistor, said voltage across said field effect transistor being substantially proportionate to the electrical current flowing through said electrical motor;
a pulse width modulated output for electrically driving said electrical motor, said pulse width modulated output being responsive to said current sense input such that, when the voltage at said current sense input exceeds a predetermined level, the duty cycle of said pulse width modulated output is reduced to an overload monitoring level.