Monday, 4 March 2013

RC electronics Part 4 - Full metal scale Land Rover

The LANE Boys residence currently hosts a very special scale truck for light installation: a custom built full metal Land Rover Series 2 SWB. A good opportunity to see how much energy is needed to run such a RC car.


The Landy weighs 5kg and measures 60 x 25 x 34cm (length x width x height). It runs on 2.2" wheels with RC4WD Rock Crusher H/T 2.2 tires. It is powered by a Kyosho G20 540-size brushed motor, using a gearbox from a battery powered electric drill. The gear reduction gives the car a top speed equal to a gentle walking pace. The power is regulated with the cheap China brushed ESC that is quite popular in our region.

We ran the car in the local park. The Eagle Tree Systems eLogger was used to log battery voltage and current consumption. The car was running on a half-empty Zippy 5000mAh 2S LiPo battery.

First we tested the power consumption of the steering servo and the light installation. When suspending the vehicle in air interestingly the servo consumed much more power than when the vehicle rested on its wheels. The Towarpro (!) MG996R servo peaks at above 1.3A, which is more than the 1A that BEC is rated at.

Even with all lights on the power consumption does not rise significantly. With 14 LEDs lit the consumption is only about 260mA.

In the park we first checked the power consumption without load. When suspending the vehicle in the air it consumes about 4.2A. When run on a flat surface at full speed the power only increases slightly to 4.5A.

We then did some light crawling over a few roots. The current never exceeded 8A.

We then went to a more challenging crawling spot: a steep incline where the recent heavy rain exposed a lot of large roots. The Landy had quite some troubles climbing over the roots and up the short hill, but made it eventually after several trials.

Here we got a peak of 14A, the highest we measured during the whole run. But the current rarely got beyond 10A.

We then proceeded with causal driving in the park for another half an hour. The current consumption rarely exceeded 7A. The LiPo voltage gently dropped below 7V during the run. The voltage during load never dropped significantly due to the low current demand of the vehicle.


Even though this Landy is large and heavy, its power consumption is significantly lower than our humble Tamiya CC-01. This is explained by the large gear reduction of the Landy -- the CC-01 is a race car in comparison. One can easily run such a large and slow scale truck with the smallest ESC you can find in your toolbox.

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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