The red plug is for a separate receiver battery to power the meter if the source voltage is less than 4.5 volts
As you begin to build your own models or retrofit an existing model with a new power setup, a wattmeter begins to make a LOT of sense – Ed Anderson's article "Who Needs a Wattmeter" sums it up very nicely – actually it's cheap insurance compared to burning out a motor or ESC.
The Whattmeter can be powered by the battery you're using or by a separate receiver battery if needed. The display will show Amps, Volts, Watts, AmpHours and WattHours (the latter two alternating every few seconds in the LED). The pic below shows the display with just a battery connected:
With a motor hooked up, it will display the following:
The receiver battery is optional – as long as the source battery's voltage is 4.5 volts or more, a separate battery to power the meter is not required. I'm going to show this application in some detail in an upcoming article – it's a VERY powerful tool for optimizing the performance of a particular motor/prop/ESC/battery combination. You can use your transmitter and receiver rather than the servo controller if you don't have one, but I found it a lot easier to use the servo controller.
If your charger does not have an LED display, the Whattmeter can serve as your display:
And finally, you can also use it to display what happens as you discharge a battery:
CONCLUSIONS
Frankly if you mix and match your electric setup, how you can do this efficiently without measuring what's going on can be an expensive hit-or-miss game – a wattmeter such as AstroFlights's Super Whattmeter (Model 101) should be in your kit bag. I know it's opened my eyes to prop/motor combinations that I would not have considered before.
AstroFlight Super Whattmeter
One of the essentials for the model builder
As you begin to build your own models or retrofit an existing model with a new power setup, a wattmeter begins to make a LOT of sense – Ed Anderson's article "Who Needs a Wattmeter" sums it up very nicely – actually it's cheap insurance compared to burning out a motor or ESC.
One wattmeter that can meet your needs is the Super Whattmeter (Model 101)
The Whattmeter can be powered by the battery you're using or by a separate receiver battery if needed. The display will show Amps, Volts, Watts, AmpHours and WattHours (the latter two alternating every few seconds in the LED). The pic below shows the display with just a battery connected:
With a motor hooked up, it will display the following:
In the Astro Super Whattmeter, Model 101, User Guide, there are three diagrams which depict Whattmeter setups – to measure a motor setup requires the following:
The receiver battery is optional – as long as the source battery's voltage is 4.5 volts or more, a separate battery to power the meter is not required. I'm going to show this application in some detail in an upcoming article – it's a VERY powerful tool for optimizing the performance of a particular motor/prop/ESC/battery combination. You can use your transmitter and receiver rather than the servo controller if you don't have one, but I found it a lot easier to use the servo controller.
If your charger does not have an LED display, the Whattmeter can serve as your display:
And finally, you can also use it to display what happens as you discharge a battery:
Frankly if you mix and match your electric setup, how you can do this efficiently without measuring what's going on can be an expensive hit-or-miss game – a wattmeter such as AstroFlights's Super Whattmeter (Model 101) should be in your kit bag. I know it's opened my eyes to prop/motor combinations that I would not have considered before.