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  1. #1
    RC Racer
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    Safe to bypass preliminary LVC with telemetry?

    While suffering from the infamous "preliminary LVC" of the VXL-3s from time to time, I have no plans of replacing it for another ESC in my Slash 4x4, just not yet.

    So how do you guys think of setting the VXL-3s in NiMH mode (so no LVC) and to set an alarm in the Traxxas Link app on the iPhone?
    The Traxxas Link alarm (can be set for certain temperature and voltage) works well: the iPhone starts ringing and vibrating, so your entire transmitter basically shakes in your hands.
    When running 3S I could set the alarm to go off when the voltage reaches 10V (3.33V/cell) and then when it goes off, just stop driving.

    Good idea? Anyone out there doing this already maybe?
    Greetz, JEREMY.

    RCblog.nl - Summit*ERBE*Sl4sh

  2. #2
    RC Enthusiast
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    It does sound like a handy use of the technology. An alternative is to buy the aftermarket on board alarm that rides in the chassis and emits an audible signal when the low voltage is detected.

  3. #3
    RC Turnbuckle Jr. vxlrocket's Avatar
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    that's a darn good idea. since the vxl-3s came out 4-5 years ago, it's always had the low voltage cutoff issue. i bypassed mine by shutting it off and using a novak smartstop, but if you can do it with telemetry now, that's even better.
    Associated rc8TE, rc8.2E, B4.2, Ofna LX2E, Slash

  4. #4
    RC Turnbuckle Jr. El Sob's Avatar
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    I suggest setting it for a higher voltage. I have mine set at 3.5. It's just to be on the safe side of keeping my lipos happy. You might loose a couple of minutes of runtime but its worth it to me.
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  5. #5
    RC Racer
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    Alright, have tested it out.
    Have put the VXL-3s to NiMH mode (red light) and set the Voltage alarm in the Traxxas Link app at 10.5V (~3.5V per cell for 3S).
    Balance charged my 3S pack and went out for a ride.

    The Voltage alarm in the Traxxas Link app went off as soon as it measured 10.5V. You can't miss it: the iPhone vibrates and emits a recurring beep. So basically your entire TQi transmitter vibrates in your hand, with the app showing you a blinking red Voltage value on screen.

    The funny thing is that it actually lets you know when you're about to reach the set pack's end, because when it reaches (in my case) the 10.5V for only split-second under load, it already starts vibrating and alarming, but only for like 1 second, because the pack then goes back up to like 10.8V when you release the throttle.
    When it really went 10.5V without going back up, the alarm went off uninterrupted.

    With the VXL-3s being in NiMH mode, you'll keep power, so while carefully watching the remaining voltage, I kept driving (with alarm begging for attention) until the iPhone pointed at 9.6V (3.2V per cell).

    Back at home my LiPo monitor displayed around 3.28V per cell, so they had regained voltage a bit like they do, but the bottom line is: very happy with this solution and no more preliminary LVC cut-offs from the VXL-3s!!

    I really like that Traxxas TQi telemetry stuff as it's not only accurate, but having realtime display of speed/rpm, motor temperature and LiPo voltage really adds to the already bigtime fun I have with those things.
    Last edited by Tjon; 10-10-2012 at 09:14 AM.
    Greetz, JEREMY.

    RCblog.nl - Summit*ERBE*Sl4sh

  6. #6
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Hey good find man!! I didnt know it had that setting. Of course I havent messed with my Sl4sh with the TQi and voltage tab in a while. I'm going to have to check it out. Thanks!!!
    Weak Revenge
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  7. #7
    RC Champion
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    Good work around.
    From an engineers viewpoint I would tend to want to keep anything that is radio controlled out of the equation for LVC. I would prefer Rockets solution of the smarstop. Its all hardwired with no human interaction involved. Battery goes low, it cuts the throttle. Often adrenaline will over ride common sense in quitting after you get an alarm. Pretty much everyone ignores the check engine light until the engine stops.

    The radio alarm would make a nice backup plan, just not a primary IMO

  8. #8
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Good point. I will have 3 ways of assurance now. LVC/ LVD on my CC MMM, LVA Buzzer, and now the TQi voltage tab and Link Software. LOL
    Weak Revenge
    Strong Forgive
    Intelligent Ignore

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