My thanks to RC-Electronics-USA for the supply of the "Watt's Up" for review.

The version of the Watt's Up under review in this article is WU100, V2.

The Watts up wattmeter and DC ammeter is an in-flight data monitoring device designed to provide the user with a plethora of information regarding their power systems vital statistics. The device does not record the entire flight data like some other on board monitoring systems. Instead it records the highest values of certain key parameters and the average values. It records these values based on measurement from when it was turned on to the current point in time. This means you can land and check the meter and see your average and peak values for the flight so far. The unit itself weighs 2.3 ounces and is 2.8 x 1.7 x 0.83 inches in size. It's specifications for volts and amps are 4.0V-60V and 0-100A. This is certainly a much higher specification than the typical values that a T-Rex might produce. The ammeter will measure down to 0V if the user uses the auxillary power input with any 4V-60V source.

Before I cover some more of the technical specification here are some pictures of the device itself :

The full manual can be found here

RC Wattmeter Simulator showcases the Watt's Up DC ammeter.

Watt's Up RC Wattmeter home page

The Watts up DC Ammeter is very simplistic in terms of how it is connected into the power system. The lithium pack connects to the wires labeled as source and the speed controller connects to the wires labeled as load. Upon connection to a battery the Watts up ammeter immediately starts monitoring the power system after going through it's very short initialisation. The device displays at all times a real-time view of the amps volts and Watts currently being consumed by the power system. In the bottom left of the display the device cycles through various monitored or calculated values. These values are minimum volts, watt hours, amp hours, peak watts and peak amps. The cycle time on the display of these values is two seconds.

The unit has a very clear and easily readable liquid crystal display which is on at all times whilst the ammeter is connected to a power supply.

The full specification for the DC ammeter is as follows:

0-100A, resolution 0.01A
0-60V, res. 0.01V
0-6000W, res. 0.1W
0-65Ah, res. 0.01Ah
0-6500Wh, res 0.1Wh

The ammeter has a very low resistance (0.001 Ohm) and the circuitry only draws 0.007A. Effectively this means the ammeter has no more affect on the power system than an ordinary piece of wire. The ammeter is also capable of measuring peak and miniumum values lasting a fraction of a second.

The unit is not as small as some in-flight power analysers and the reason for this is that it has quite a large display. In many ways this makes this a more useful field device than some of the other in flight recorders that require a computer to analyse the data once you return from the field. I considered mounting the Watts up on the side of my T-Rex where it would actually fit quite nicely. However, my flying field is currently a muddy bog and I wanted the ammeter to be protected from the wet. Therefore I decided that unusually (for trextuning) I would test this DC ammeter on my Logo 10. Another place where the ammeter would fit is in the front of the canopy on top of the lipo, certainly this would be OK in a 3S setup, I run 4S so space here is very limited. I tested this on an Align carbon frame and the ammeter fitted quite nicely with the LCD display visible through the clear canopy. A picture of this can be seen in the photos below. RC-Electronics inform me that the device can be uncased and in this instance the weight is only ~1.7 ounces. Taking the unit out of it's casing does void the warranty.

The pictures below show the ammeter connected to the Logo 10 and then a series of pictures showing what the ammeter was displaying at the end of my flight.

Working with the data displays one at a time from the above, working left to right, top to bottom :

The first display is showing the amps, volts and watts (real time). Obviously the machine isn't flying at this point so the values show very low amp draw (0.05A), volts stable at 18.15 volts and approx 1.0W of power being consumed. The value of interest is Ap, which is showing 42.85Amps as the peak amps pulled during the flight.

The next display shows the same A, V and W values with the interesting reading being Vm (volts minimum) of 16.46V.

Next display shows Wp (Watts peak) with a value of 708 Watts as the peak output of the motor during that flight.

Next display shows Wh (Watt hours) consumed as 53.8 Watt hours. This value takes into consideration variation in voltage on total energy consumed (Ah x Volts).

Last display shows Ah (Amp hours) consumed as 3.107Ah, the Logo10 uses a 3.7Ah pack, so I have landed with about 600mah left in the pack. This is one of the most useful readings on the device as you can see immediately whether you are nearing the pack capacity each time you land. Also over time you could see how your pack is coping from flight to flight in terms of power delivery. The Ah value does not take into account variation in voltage on total energy consumed.

As an in flight aid this is everything the Watt's Up offers, it is not meant to be a graphing or plotting type device but a real time monitor which you can easily read at the field to monitor your flight performance. In this regard it is beautifully simple and does exactly what it says on the box.

The watt's up can also be used to monitor the charging of batteries by connecting it between your charger and the lipo. It will show the voltage and amp settings for the charge as well as recording the total capacity put into your pack in Ah. Useful if your charger doesn't have a display to show you this data. Also the ammeter can be usefully employed in a bench test environemnt to show real time data for a strapped down heli and it's power system, although I would argue that the computer connected graphing type solutions are probably better at producing data for this sort of work.

Conclusion

The 'Watt's Up' Watt Meter and DC ammeter is a straight forward in flight data monitor. It is designed for use at the field giving immediate feedback on flight performance using it's nice large LCD display. It is quite rugged in it's build and simplistic in terms of it's fitting to the model. It monitors all the important functions of the power system providing both real time, peak and accumulated values. It does this simply, clearly and is by far the easiest device I have used for flight time monitoring.

On the negative side it is quite large and is a bit of a tight fit inside the T-Rex canopy. I would have preferred a slightly smaller display which would reduce the form factor and allow for some more versatile fitting options to the model.

Overall I like the device, it gives direct feedback at the field and doesn't require a computer and graphing software to get the data you want. If the form factor was smaller I would highly recommend the 'Watt's Up' but due to the size I feel that it is not ideally suited to the T-Rex. Certainly I was much happier with the device on the Logo10 where space isn't an issue and would not hesitate to highly recommend this device for larger models. As it is, I feel this device would find itself occasionally fitted to my T-Rex to get some quick data but it would be an inconvenience to have it fitted all the time.

If you have the 'Watt's Up' please rate it using the T-Rex Tuning rating system ....