Friday, 1 March 2013

RC electronics Part 3 - Tamiya CC01 power consumption

In this blog post we look at the power consumption of the Tamiya CC01 Unimog.

The CC01 chassis is a very small 1:10 scale chassis available with several bodies. Beside being small it is also light-weight. Our CC01 Unimog is basically in a stock configuration with the traditional Tamiya silvercan brushed motor. Both front and rear axles have locked differentials for better trail performance. The car is already quite beaten up.

The data was recorded in the picturesque Woodgrove area in the north of Singapore. The surface is mostly compact sand with small rocky formations sprinkled in.

The Eagle Tree Systems eLogger was used to log battery voltage, battery current, motor temperature and throttle position. The car was running on NiMH batteries.

The graph above shows the throttle position during the measurement period. The youngest of the LANE Boys was driving the vehicle during the test. At first he drove gently as part of the SG Crawlers outing, but after about an hour he got bored and started to "bash" the little Unimog.

The first 4500 mAh NiMH battery lasted about 105 minutes. After that we changed to a 3300 mAh NiMH battery. The logger's memory ran out before the end of the run.

The peak current draw of this little vehicle is only 24A, corresponding to roughly 140W. The current draw rarely exceeds 15A, and gentle driving consumes less than 5A.

Even a freshly charged NiMH battery drops below 8V almost immediately. Voltage drop at moderate currents is also quite high with 1V or more.

At the end of the charge the battery voltage drops very fast and reaches values below 6V before the ESC cuts out.

The bathtub-style chassis of the CC01 provides little cooling to the motor. When driven hard the motor temperature climbs to a toasty 85 degrees Celsius. Note that the ambient temperature was around 30 degrees Celsius during the test -- it is hot here in Singapore even at Christmas time!


The light CC01 chassis combined with the relatively low power of the brushed motor does not challenge modern batteries or ESCs. Cooling the relatively inefficient brushed motor is a concern though.

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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