Battery Voltage Display

VEX V5 Technical Support
#1

At competitions, I’ve seen teams have displays on the battery chargers showing the voltages on them. How do they do this and where can you buy the materials? Thanks.

#2

You need an analog to digital converter of your choosing and basic electronics skills.

Or, if you want to be lazy, just get this.

#3

Be aware that buying from the China warehouse can take quite a long time for shipment. The US warehouse costs a good bit more, but you usually get things more quickly

#4

You could always just get a handy dandy LCD and display the voltage on there.

task LCD()
{
	while(true)
	{
		clearLCDLine(0);
		clearLCDLine(1);
                string mainBattery, expander;
		bLCDBacklight = true;
		displayLCDString(0, 0, "Primary: ");
		sprintf(mainBattery, "%1.2f%c", nImmediateBatteryLevel/1000.0,'V');
		displayNextLCDString(mainBattery);
		displayLCDString(1, 0, "Lift Bat: ");
		sprintf(expander, "%1.2f%c", ((SensorValue[importantVoltagePort])/270.0)-0.775, 'V');
		displayNextLCDString(expander);
		wait1Msec(100);//This has to be here or everything will go wrong and will look like the LCD is dying.
	}
}
#5

You can make your own with a part from Adafruit (underneath it all, it’s probably the same as the one linked above!). Full explanation in my article on batteries (this link goes straight to the build-your-own-voltmeter section). We have one. Love it. It’s not connected to our smart chargers directly; it’s a stand-alone item and pathetically easy to use:

  1. Plug in battery
  2. Read voltage in giant lighted numbers
#6

How would you display the voltage while the battery is charging?

#7

You would have to modify the charger, which (iirc) is illegal for competition.

#8

Not necessary at all.

You would need to connect your ADC to the battery and charger while charging. This requires both a Tamiya male and female connector. And you should note the reading will be slightly high while charging.

#9