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  1. #1
    RC Racer
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    Aug 2013
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    239

    Comparing iPhone Speedometer GPS vs Traxxas Link computed speed

    Just to get an idea of the difference between a GPS and Traxxas Link, this is what I get on my

    2WD slash stock out of the box set up using a 7cell NiMH 5000 mAh battery at starting charge of 9V (not fully charged). Traxxas link reads 36 mph, iPhone GPS reads 31 mph over an average of 4-100 yard speed runs.

    ERBE using 18/54 gearing, road rage taped but not balanced tires on 1/2 offset desperados, 3s at starting voltage of 24.6v by traxxas link (12.22v + 12.17=24.39v measured on voltmeter). Traxxas link reads 60 mph, iPhone GPS reads 46.5mph over 6-100 yard speed runs.

    25F outside


  2. #2
    RC Champion
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    Jul 2012
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    Yakima, Washington
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    1,420
    Wow the run on the e revo is quite different.
    With great brushless comes great responsibility.

  3. #3
    RC Racer
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    Aug 2013
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    239
    Stock summit speed run using 2 5000 mAh 7 cell NiMH fully charged to 9.86v (measured 45 min off charger) + 10.35v (immed measured off charger) starting at 20V on Traxxas link, multiple 100 yard speed runs totalling 1.32 miles over 10 minutes at 25F yields a Traxxas app link max speed of 20 mph and GPS speed of 19.8 mph.

    eRevo speed probably higher than GPS in part due to slipper clutch slipping though I did try to run smooth accelerations, but under 6s, I just can't resist really pushing the ERBE ... soooo much fun. Actually I equally enjoy Summit, Slash 2WD, ERBE for the different driving characteristics.

    Summary

    ERBE : 46.5 mph on GPS; 60 mph on Traxxas Link
    Slash 2WD: 31 mph on GPS; 36 mph on Traxxas Link
    Summit : 19.8 mph on GPS; 20 mph on Traxxas Link

  4. #4
    RC Racer
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    Aug 2013
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    Slash 2WD: 46.2 mph on GPS; 56 mph on Traxxas Link using 3S LiPo fully charge in 17F weather over 2.48 miles
    Slash 2WD: 31 mph on GPS; 36 mph on Traxxas Link using 7cell NiMH over 1.32 miles

    Both using balding stock BF goodrich tires

  5. #5
    RC Competitor
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    Dec 2011
    Location
    Riyadh, KSA
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    75
    Stock summit speed run using 2 5000 mAh 7 cell NiMH fully charged to 9.86v (measured 45 min off charger) + 10.35v (immed measured off charger) starting at 20V on Traxxas link, multiple 100 yard speed runs totalling 1.32 miles over 10 minutes at 25F yields a Traxxas app link max speed of 20 mph and GPS speed of 19.8 mph.

    I was wondering if Traxxas would consider doing a film-ware upgrade to include accumulated miles that we put on our vehicle especially the Summit as I would like to use it when hiking in the woods. I am getting max speed of 19 on my TQi Summit Setup. The truck is two years old and using two 7200 mAh batteries.
    Summit
    Slayer Pro 4X4

  6. #6
    RC Racer
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    Aug 2013
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    239
    I think Traxxas has a problem deciding which way to go with the Telemetry given the changes Apple has made to the iPods:

    1. Switch to lightning connector means Traxxas would have to make an all new docking port with lightning connector instead of the 30 pin connector.

    2. Maintain and/or upgrade the Traxxas Link app to handle both legacy 30 pin and lightning communication may be more problematic than just abandoning the 30 pin (and all of us who bought into it), but it seems they already have.

    3. Problems with firmware upgrades completely disabling the TQi

    Accumulated miles would be nice, but is also problematic given what Traxxas is willing to provide its fan base

    A. The preference configurability of the Traxxas Link App is limited to a few sets of available wheels without a method to input tire circumference or diameter (regardless of brand) ... a necessary component in order to determine distance traveled per rotation of the pinion

    B. Easy way to determine the drive ratio ...

    Drive Ratio = Transmission Ratio x Gear Ratio
    Gear Ratio = Spur/Pinion
    Transmission Ratio = Diff Gear/Input Gear (for 3 gear transmission)

    Roll Out = tire circumference/drive ratio = distance rolled per rotation of pinion

    C. Too much slipper slip and the pinion spins more than the wheels rotate resulting in miscalculation of speed and distance. One will have a number greater than the actual distance traveled.

    The only way to have a reliable odometer then is to have an external GPS or data tracker and keep a log.


    http://losi.com/Articles/Article.asp...58187178,d.aWc

  7. #7
    RC Racer
    Join Date
    Dec 2013
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    190
    Quote Originally Posted by Dementor View Post
    Just to get an idea of the difference between a GPS and Traxxas Link, this is what I get on my

    2WD slash stock out of the box set up using a 7cell NiMH 5000 mAh battery at starting charge of 9V (not fully charged). Traxxas link reads 36 mph, iPhone GPS reads 31 mph over an average of 4-100 yard speed runs.

    25F outside

    How are you getting 31 out of a stock 2WD Slash?!

    I had to upgrade to Velineon and I only get 32 out of the NiMh battery. Are you using the regular Titan motor? And what are your gears? Are they stock? Or did you change them?
    Last edited by Dadx2mj; 01-12-2014 at 09:40 AM. Reason: Language

  8. #8
    RC Racer
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    Aug 2013
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    239
    Mine is a stock 2WD VXL Slash.

  9. #9
    RC Racer
    Join Date
    Dec 2013
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    190
    Ahh that explains it lol

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