Tom's R/C Electronics Gadgets & Projects, R/C Battery Voltage LED Monitor Project (Simple-Volt)

Updated: May 14, 2007

PICAXE Projects: "SIMPLE-VOLT"
History	Parts	Building	Firmware/Code	Testing & Operation	Notes

Note: All pictures that follow are "clickable". Clicking on them will show you an enlargement!
Under Construction

A lil' history ...
This project involved the building of "SIMPLE-VOLT", a tiny, light-weight R/C Battery Voltage Monitor using the PICAXE microcontroller. This simple PIC project includes a simple A-to-D application that measures the voltage of a battery pack via a resistor divider network, compares it to a reference voltage (5v regulator) and then displays the battery voltage on 2 LEDs (indicating battery voltage strength). As a visual warning, all LEDS flash fast and beeper sounds to indicate that the cutoff voltage has been reached, telling you to land and stop discharging the depleted LiPo pack (trust me, this saves LiPo packs!).

The Simple-Volt automatically detects the number of LiPo cells connected (assume charged pack) and continually monitors the battery voltage and compares it to the preset cutoff/warning voltage corresponding to the number of detected LiPo cells (9v for 3s, 12v for 4s and 15v for 5s... basically, 3 volts minimum per cell).

When the battery voltage is greater than the cutoff voltage +1v, the Green LED will be on solid. If the battery voltage is > cutoff voltage+.5 but <cutoff voltage+1v, the Green LED will slowly flash. If the battery voltage of >cutoff but <cutoff+.5v, then the Red LED will begin flashing. If the battery voltage is less than the cutoff voltage, both Green and Red LEDs will flash very fast while also emitting an intermittent beeping sound from the peizo alarm buzzer.

The user can also set the Simple-Volt so it either locks onto the first instance of the cutoff or automatically resets once battery voltage increases. By default, the Simple-Volt will be in "Locked" mode once powered up (when cutoff is reached, LEDs flash and alarm sounds continually until power is removed). To get the Mini-Volt into "Auto" mode (where flashing LEDs and alarm reset once battery voltage recovers above the cutoff voltage; as if the throttle was decreased) , you would connect the Mini-Flash to power for less than a second and then disconnect. Then, reconnecting the Simple-Volt to power will put it into "Auto" mode.

..more coming soon