Tech-Aero Designs Throttle-Tech

Written by Earl Haury

The Throttle-Tech (TT) by Tech-Aero Designs ( is a nifty device to help E fliers manage power. The website provides links to documents that describe the TT and how to use it. I’ll try to add to that info with my own observations and experience.

With E power it’s obvious that power is better early in a flight when the battery charge is high and diminishes throughout the flight as battery charge declines. A big part of mastering E flight is learning to manage the throttle so as have constant performance throughout each flight. Lay on the throttle early and, while the performance is super, “fuel” needed for later in the flight is wasted. Additionally, battery performance varies with C rating and age which can provide the effect of “changing nitro” for each flight.

Motors are designed with a K/v factor which is, essentially, rpm = (K/v rating) x v (minus an efficiency constant). This means the motor rpm varies with voltage supplied. An important E distinction is that the rpm will be the same for a given voltage regardless of load (within design parameters), increasing load will only increase current draw.  Controllers vary their duty cycle (% time on vs. % time off) basis the throttle pulse width provided – basically full throttle is 100% on, half throttle 50%, etc. It’s important to note, that within the designed operating range, the controller doesn’t regulate voltage, amperage, or rpm – only duty cycle. (Outside the designed operating range the controller limits amps by releasing smoke.) A reasonable way to understand all this is that stick position relates to the percentage of battery voltage going to the motor. Ends up much like glow – more stick, more power.

The rub lies in that the battery isn’t a constant voltage source. While the full charge battery voltage may be similar from pack to pack, output voltage will vary with load and internal battery resistance. We’ve accepted this for a long while with servo power/speed and most use a voltage regulator so as to have consistent servo performance. I’ve long wanted a voltage regulator for the motor battery to do the same thing. Unfortunately a DC voltage regulator that operates at 37v / 100A weighs a ton, forget the cost!

The Throttle-Tech is an elegant solution put together by Ed Alt of Tech-Aero Designs. The TT monitors battery voltage and alters the throttle channel pulse to maintain a constant power level for a given stick position. In use, the TT “closes the throttle” a little when the battery is at full charge, then returns that “throttle” as the flight progresses and battery charge drops, making throttle management easier for the pilot. The authority of the TT is adjustable, as is the point of stick position it begins working. Added features are that it will indicate a low RX battery and/or a low motor battery before flight. Anyone who has taken off with a discharged battery will appreciate the latter. All this for 15 grams.

When using the Throttle-Tech there are some important things to understand. Initial full power will be lower than without the TT. The TT cannot provide more power than that observed with a full charged battery and the TT active. This means that the in-flight output with the TT cannot be more than that of an initial ground run (or sound test). The amount power is reduced is dependent upon the TT settings, battery voltage, and controller settings. The TT adjusts the throttle pulse going to the controller from the receiver and isn’t affected by transmitter throttle curve settings. However, controller settings can influence TT effectiveness. I find a linear controller curve (if selectable) and fixed end points that provide 600 microseconds range works best. (1.1ms low – 1.7ms high)

In flight, a fresh high C battery will be “tamed” more than an old low C battery (which the Throttle-Tech might not reduce at all). The “tamed” battery / TT will provide very consistent performance throughout a flight. Performance with the “old” battery will fall off as the flight progresses – the TT cannot provide power that isn’t there. I find that the TT does an excellent job of providing consistent flight to flight, as well as in flight, performance when using a group of “good” batteries in various states of their life. Overall the Throttle-Tech is an excellent product that can help a pilot from overpowering early maneuvers and hammering the battery to finish a flight. I’ve found the line of Tech-Aero voltage requlators to also be high quality products.

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