RC electronics Part 5 - Drift car power consumption

In part 5 we look at the electric power consumption of a 1/10 scale 4WD drift car.

The test subject is our Tamiya TT01D. We obtained the car second hand quite a while ago. It was originally an Expert Built set but has been substantially modified by the previous owner. It has the obligatory aluminium propeller shaft, a carbon fiber upper deck, a front one-way differential, sway bars, and a HobbyWing EZRun 60A brushless system with a 5.5T motor. The tires are well-worn HPI T-Drift. A 4600mAh 2S 30C LiPo provided energy for the car.

Verifying KV

First we verified the KV of the motor using the Eagle Tree Systems eLogger with the brushless motor sensor.

We held the car in the air while pushing the throttle to full speed. The motor achieved a staggering 49500 RPM. At 8.2V this corresponds exactly to the 6000 KV that is specified for this motor.

The current was just above 6A. No-load power consumption is therefore 50W.

Drifting

The test took place on the tiled surface of an HDB public shelter. The smooth surface makes for nice, flowing and easy to control drifts.

This slippery surface is very gentle on the power. The data logger was full after about 35 minutes of drifting. During this time the current rarely went above 8A, a single peak of 14.6A was recorded.

The average current during the session was below 3A. It takes only a measly 20W to power this drift car on average!

With the standard TT01 gearing the motor RPM stays below 18000 RPM most of the time. Sometimes peaks of about 26000 RPM occur. Note that the peaks above 30000 RPM in the chart above are measurement glitches that the logger produces when the brake function of the ESC is applied.

The chart shows that the 5.5T motor is overkill for a drift car. An 8.5T would work just fine. This is also confirmed by looking at the throttle input:

During the whole session it was never necessary to apply more than 50% of the forward throttle range.

A closer look at slow and fast drifting

We usually build our drift course by placing a couple of plates on the floor. Depending on how you choose your course you can either drift tightly around individual plates, or do larger manoeuvres around the whole area.

Tight manoeuvres require less wheel spin, roughly by a factor of two compared to large circles.

Interestingly the throttle input looks almost identical to the RPM measurement.

The effect on the current consumption is not pronounced though. While the peaks are taller in the high speed section, the average current is only affected minimally.

Conclusion

Drifting is very gentle on the electronics. A decent 4000 KV motor is sufficient, and there is no need for a high-amp ESC or a high-discharge capable battery. A 4600mAh battery lasts more than an hour of drifting in this TT01. The concentration of the driver usually wears out quicker ...

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All articles in this series:
Part 1 - Tenth scale 4WD Buggy power consumption
Part 2 - Battery charging
Part 3 - Tamiya CC01 power consumption
Part 4 - Full metal Scale Land Rover
Part 5 - Drift car power consumption

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