Patent ID: 8055463

Claim:
A fuel gauge for fuel cells, batteries, and solar power systems ( 4 ), the fuel gauge comprising: a voltage pre-regulator; a main voltage regulator in communication with the voltage pre-regulator; a current sense resistor in communication with the main voltage regulator; an integrator comprising an op amp and a capacitor, wherein the integrator receives power from the main voltage regulator, and receives a voltage proportional to current from the current sense resistor; a microprocessor comprising data storage and a hysteresis circuit, wherein the microprocessor operates in a low power state until activated by a resistor, and wherein the data storage comprises computer instructions for instructing the microprocessor to convert the voltage proportional to current to a monotonic uni-polar representation of an aggregate number of electrons; and wherein the resistor is disposed between the integrator and the microprocessor for activating the microprocessor from the low power state prior to saturation of the integrator with the voltage proportional to current; and a reset circuit disposed between the microprocessor and the integrator for resetting the monotonic uni-polar representation of an aggregate number of electrons to zero.