External and internal power management for embedded electronic devices

A power management system for an embedded electronic device to manage internal and external power sources used to power the embedded electronic device comprising:

• an internal power source;
• a microprocessor;
• an external protection switch connected between the external power source and the embedded electronic device;
• an external power sense circuit configured to measure the voltage of the external power source;
• an internal power switch connected between the internal power source and the embedded device;
• an internal power under-voltage lockout control circuit that controls the internal power switch;
• an internal power sense circuit configured to monitor the voltage of the internal power source;
• an external power voltage monitoring circuit configured to monitor the voltage of the external power source;
• an internal power charger circuit configured to charge the internal power source;
• a power path control circuit that is configured to select the appropriate power source depending upon the availability of the external and internal power sources;
• wherein, the microprocessor is configured to determine when to power the embedded electronic device from either the internal or external power source, when to recharge the internal power source, and when to shut down the embedded electronic device so as not to over discharge and damage the internal power source when the external power is low or not available.

A battery management method of an electrical device, having an internal power source and an external power source, the battery management method comprising the steps of:

• detecting, by the battery management unit, whether the electrical device is electrically connected with the external power source;
• determining, by the battery management unit, whether the external power is within a nominal range, and if the external power is below the nominal range then determining, by the battery management unit, whether the internal power source is above a threshold level;
• if it is determined that the external power source is below the nominal range and the internal power source is above a threshold level then the battery management unit is configured to power the electrical device using the internal power source while operating the device at a reduced functionality;
• if it is determined that the external power source is above the nominal range and the internal power source is above a threshold level then the battery management unit is configured to power the electrical device using the internal power source while operating the device at a reduced functionality and disables charging of the internal power source.

A vehicle monitoring device that is adapted to receive signals and power from an on-board diagnostics port of a vehicle, the vehicle systems monitor comprising:

• a microprocessor adapted to receive signals from the vehicle;
• an internal power source for powering the processor;
• a charging system configured to charge the internal power source from power from the vehicle;
• the microprocessor configured to determine whether the device is or is not connected to the power source from the vehicle, if the microprocessor does not detect power from the vehicle and the internal power source is depleted, the microprocessor waits for the power from the vehicle to be available before charging the internal power source and powering the device;
• if the microprocessor detects power from the vehicle and the power from the vehicle is within a threshold voltage, the processor uses power from the vehicle to power the device and to charge the internal power source;
• if the microprocessor detects that the power from the vehicle has declined below the threshold voltage, the microprocessor discontinues drawing power from the vehicle and begins drawing power from the internal power source to provide uninterrupted power to the device without depleting the power from the vehicle.