RC Car/Truck Power & Setup Calculator :
| RC Car/Truck Power & Setup Calculator : |
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Tips: |
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- Internet Explorer must 'allow blocked
content' to use calculator scripts.
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- To easier compare setups, define two
Restore buttons, use 'undo' and 'redo' buttons or launch 2 versions of
the calculator page
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- Things to be taken into consideration
when assessing the calculator results: Rollout: is just an interesting number that you
may or may not find a useful indicator for your setup. For a small RC
electric vehicle, some might say that a rollout of around 1 inch per
motor rev is thought to be a good starting point for a setup BUT
this doesn't mean you should aim for this religiously. It depends greatly
on your desired application and the performance abilities of the setup's
components (cells, motor and ESC etc.). There is no allowance in the
calculations for actual real work performance with regard to torque
and heat issues. In other words, a setup that looks good on paper in
theory may over heat and destroy itself in the real world. You need
to apply some experience and be prepared to carefully experiment what
works in your application (on road, off road, big or small), balancing
performance for acceleration vs. top speed vs. component life span etc. Just because the numbers look good in the calc doesn't
mean your motor and cells can deliver the required torque and cope with
the associated heat demands of your setup configuration. We are not
modeling for friction, air drag, tyre swell and such as like can impact
upon your top speed. The calculator should really be thought of as an
estimator at best (think 'ball park'). How accurate is the motor kv (rpm/v) rating, some motor
winds seem to vary. - Trans ratio (short for transmission ratio) is also known as the car's internal ratio which is built into the differencial gears. The internal ratio is multiplied by the gear ratio (Spur/pinion gear) to generate the final gear ratio, the total gear ratio used between the motor and the wheels. |
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- When using the pack voltage radio button Full to Flat you will notice that Amps and Watts are also recalculated to show a lower Amp draw at higher voltages. Note the effect is exaggerated as the Wheel RPM also increases at higher voltages and would use more Amps to over come drag, something not modelled in this simple version. - Take into account the at full speed 100% throttle
your setup may have some wheel slip, tire swell (to a larger diameter),
voltage sage, motor rpm limitations, increased vibration, increased
drive train friction, aerodynamic drag... etc. |
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- Some text fields can be typed into and
auto update when clicked, tab'd away or just press return.
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- Edit the average Amp consumption rate
to estimate maximum battery pack runtime.
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- Alternatively, if you know your setup's
run time then enter the number on mins and calculate back the average
Amp draw (if 100% capacity could be used).
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- 'Efficiency/throttle'
means you can use the drop % as a throttle if you wish but remember to
drop at least 10 to 20% for real world losses. 90% is about the best zero
load performance your going to ever see. Note that ESC's throttle % are
not normally as linear.
Given that the Kv of your motor may vary +/-10% from manufactures spec, the true condition of your batteries under load, your ESC motor timing is set aggressively etc. etc. etc. all can significantly impact real life numbers. You get the picture though right ;)... ball park estimates. |
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Formula:
Wheel RPM = (Motor RPM/V * Battery Voltage) / (Spur Gear Teeth / Pinion Gear Teeth) * (% Efficiency /100) Runtime max without losses = (Battery Capacity Ahrs) / (Amps average) * (60 mins) Or Amps average = (Battery Capacity Ahrs) / (Runtime) * (60 mins) Road speed KMH = (Wheel RPM * 60 mins) *
( (22/7) * Tyre diametermeter in mm) ) / 1000000 Rollout = Tyre Circumference / Total Gear Reduction.
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- There are 3 custom memory slots to save and restore custom model setups into your browser's cookies. Makes it easier to compare custom setups with one click and save model setups for another day (valid until the year 2022). There may be other malfunctions that crop up as old data is restored on a future modified web page, so may look odd. Note that the following link formats to the same page will save and restore different cookies (different domains): http://www.dhrc.rchomepage... or http://dhrc.rchomepage... - If your Internet connection is not that reliable then you can always File->SaveAs this page to your hard drive and use a local copy when ever you like. |
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- Problems with metric Kg and mm? Try this online unit converter ;) |
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Other RC car calculators and info: R/C
Calculations : Top Speed Estimator, motor and gear selector
and much more. Larger electric RC truck setup spreadsheet examples:
Repository
of RC Goodness
Need more battery and motor data? Try
these other calculators and resources: - Estimate
Electric Motor & Prop Combo from the useful Beginners'
Guide to Model Aircraft. |
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