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  1. #1
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    What am I doing wrong!? 36mph Mustang 302 with dual 2S LiPo's

    So I thought I should give electric cars a chance, I've always been a nitro car guy. So I went to my local r/c shop and bought what seemed to be a nice car, the brushless Mustang 302 vxl. I bought all the goodies, like TQi docking station, sensors for rpm/speed, temp and voltage and two 7.4V 1800mah 2S LiPo batterys!

    I changed the pinion from the stock 28t to the "high speed" 31t that comes with the car.

    The LiPos are connected parallel.

    I read the speed in the Traxxas link app where I've done model setup:
    Spur gear 45
    Pinion gear 31
    Drive ratio 5.040
    Tires 1.9" Gymkhana Slick
    Battery 4S LIPO
    ESC VXL-3m
    Motor Velineon 380

    I did not change drive ratio since I thought that it is the gearing in the transmission? Is that right?
    Is the any other possible reason for such low speed? The car feels strong from bottom to high end.
    Slipper clutch is adjusted right. Correct clearance between spur and pinion gears.

    Please help me lol. Is the only option to use dual NiMH batterys in series to reach +50mph?
    Last edited by andreas.e; 11-08-2012 at 04:04 AM.

  2. #2
    RC Champion
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    couple thing to understand on this one...

    Lipo batteries can not be put in "Series" (double voltage) on these cars, the ESC will not recognize that high of voltage and will not respond. When you go in "Parallel", all you're doing is doubling the size of the fuel tank, it will run twice as long. SO, your "4s" isnt 4s, its 2s (7.4v) and 2 times the mah (1800 x2 = 3600 mah).

    Series doubles your voltage so if you want to hit 50 in this car, you have to run 2 nimh batteries in series - you'll see the speed gains for sure this way.

    So, the only way to get more voltage into the car, 2s, 3s lipo and series nickle metal batteries.

    MAH = run time and doubles in parallel
    Voltage = power and doubles in series

    Good luck, welcome to the forums and traxxas - keep us informed of your progress and remember, "Video, or it didnt happen" - LOL!!

    "RED"
    Last edited by Redsawacs; 11-08-2012 at 04:12 AM. Reason: Old age

  3. #3
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    Thanks! I think I start to figure some of it out lol. Yeah I have understood that I would damage something (ESC) if I connected the Lipos in series. I have not done that.

    I'm thinking dual 11.1V Lipos in parallel connection might be a good idea? That should increase voltage from where I'm at now (reads 8.0V in Link app) but not as much as 2 x 7.4V i series. Am I on the right track here?

    I think the r/c shop pulled a trick on me since I told them I know nothing about electric cars but wanted to go fast (+50mph). But now I'm learing alot trying to figure this out and they must have known I would never reach +50mph with 7.4V Lipos in parallel

    But at the same time I'm seeing guys online doing like 50-60mph with similar setups. That's why I need to get some input before I go back to the store and demand to trade in my 7.4V Lipos for 11.1V's

  4. #4
    RC Turnbuckle Jr. Petertje60's Avatar
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    There might be people that tell you that it is possible to run with 4S, which would work if you switch LVC off, but that is not recommended. It will seriously shorten the lifespan of your ESC and motor. I think you will be surprised when you put 3S in it.
    50% more voltage, so theoretically 50% more speed.
    Nobody is born with experience.

  5. #5
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    50+ speeds for a 'stang are going to be hard to hit in stock trim.
    The small 1.9" tires are holding you back... the exact same gearing, motor, ESC, and battery will get you up to 40MPH in a Revo according to my speed calculator; a bit faster than the ~24MPH you are going now. Switching out a Revo to 3S would get you to about 60MPH and about 36MPH for the 'stang.

    I am not sure how you got a 36MPH reading on 2S, but my calculations are telling me 24ish should be your top out.

    I have not found many instances where the speed that the remote gives is very accurate at all... I would double check your actual speed with a GPS of some sort. I have strapped my Android to the roof of my RC's quite a few times to get accurate readings on top speed... which always have been within a few MPH of my calculations.

    To hit 50-60MPH on your RC... in theory you would need grippy tires, 3S LiPo's, and probably a 6,000kv power combo with the same gearing you have now. But I am not sure that heat will not be an issue for you geared that heavy...
    Whatever it is I just said... I could be wrong.

  6. #6
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    I've hit 34 with my Rally with 2s parallel, check'd with a radar gun. I've only ran 3s once (no radar gun though) and it was quite a bit faster. Need to check it out with the series nickle's one day.....now you got me curious!!!!!!
    Last edited by Mr.Bill; 11-08-2012 at 12:02 PM. Reason: hook'd on phonics let me down
    rc10T3, TT Sparrowhawk XXB, Slash 4x4, 1/16 Rally

  7. #7
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    Got dual Traxxas 1400mah 3S 11.1V lipos, now the link app says 56mph!
    Parallel connected.

  8. #8
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    I will verify it with GPS asap. But it feels like it could be possible. People have gotten stock cars with dual nimh in series up to 53mph from what I've read and seen online.

    Going for +60 with taller tires. And I need foam tires!

  9. #9
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    NICE!!!! Let us know how it goes...
    rc10T3, TT Sparrowhawk XXB, Slash 4x4, 1/16 Rally

  10. #10
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    If you didnt but the lipos just get a MMP esc so you can Run them in series and go like 80 mph!
    Xo-1
    Pede 4x4 PE - Slash 4x4 PE
    Miss Geico Boat

  11. #11
    RC Champion
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    congrats on 53 - have you tried the 2 7.4v in series yet? that more voltage than the 11.1v.

    OH, take one of the 11.1v batteries out of the car (reduce weight) and try it. You arent gaining anything with 2 batteries in parallel except longer run time. If you want to hit 60, try one battery or 2x 7.4v.

    Sure the Lipo battery at 11.1v is a cleaner power but its still 3 volts below 2 nimh batteries - worth a try

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