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  1. #1
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    New lipo help! ESC PROBLEMS

    So after having my bandit vxl for over a year now I have bought a lipo ( 11.1v 8400mah) it makes it go so fast but after about 10-15 mins of use my car wouldn't move but the servo for setting was , I opened the car and saw that the esc was flashing red and I couldn't turn it off , I then thought it was the low voltage check but I took my lipo back home and I still had 10.2 v so I don't know what happend!

    I would be very grateful if someone could help
    Thanks
    Last edited by Hende101; 04-05-2014 at 10:54 AM. Reason: Error

  2. #2
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    Quote Originally Posted by Hende101 View Post
    So after having my bandit vxl for over a year now I have bought a lipo ( 11.1v 8400mah) it makes it go so fast but after about 10-15 mins of use my car wouldn't move but the servo for setting was , I opened the car and saw that the esc was flashing red and I couldn't turn it off , I then thought it was the low voltage check but I took my lipo back home and I still had 10.2 v so I don't know what happend!

    I would be very grateful if someone could help
    Thanks
    It went into lvc cutoff and that's normal.
    Go Traxxas, Team Associated, and Losi!

  3. #3
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    Quote Originally Posted by Traxxasfreak61 View Post
    It went into lvc cutoff and that's normal.
    But why ? I was still on 10.2V ( I'm kind of a knob so I might be missing something here!

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    It may have been thermal shutdown, how hot was the esc ? And do you have the cooling fan for it ? If not, you should get one

    And don't forget to make sure you have the low voltage cut-off activated now that you're using LiPo, the light should be green when you switch it on

  5. #5
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    Quote Originally Posted by ScaleRider77 View Post
    It may have been thermal shutdown, how hot was the esc ? And do you have the cooling fan for it ? If not, you should get one

    And don't forget to make sure you have the low voltage cut-off activated now that you're using LiPo, the light should be green when you switch it on
    yes I turned on the low voltage cut off , the esc and motor was quite hot , will the fan fit under the body because I've had to buy the battery expansion kit to fit the new lipo in which lifts everything up including the esc
    Thanks for your help!

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    You're welcome

    All you can do is fit the fan and see if the body will clear it, you definitely don't want it to touch because there won't be any airflow. If it doesn't clear it you have two options, either cut a hole in the body (wouldn't be my first choice tbh) or move the esc to the left side of the chassis

    You should maybe buy a temp gun too so you can keep an eye on the temps, you definitely don't want to let the motor get too hot

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    thanks but im a bit stuck on money right now, do you think if i made some vents/holes in the body to allow air flow, would that help?

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    More airflow can only be a good thing, give it a go and see how you get on, you should definitely plan to get a fan asap tho. And maybe alter you driving style a bit to stop it heating up as much, constant flat-out runs all the time will make it heat up pretty quickly. I'm not saying that's what you were doing, but if it was then just be a bit kinder to it, lol

  9. #9
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    Ok , yeah I haven't hit full speed yet or even 3/4 as I don't have enough space to drive it ! Just another thing I charged my battery back to 11.1v at went for a drive ( about 5 mins ago) and after about 10 seconds it cut out again ! So I unplugged the battery and took of the body she'll then tried again and it worked fine for about 4 mins until it went to about half speed and had the red flashing light again so I checked the voltage and it was 10.9v . I have no idea what is going on !

  10. #10
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    Gear down. Get infrared thermometer.
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  11. #11
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    Quote Originally Posted by Buzzforbrains View Post
    Gear down. Get infrared thermometer.
    I haven't changed any gearing ( stock)

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    Quote Originally Posted by Hende101 View Post
    I haven't changed any gearing ( stock)
    Overheating motor and esc are first tackled by gearing down-smaller pinion. Putting fans, heat sinks, holes in body are secondary and will only help a couple degrees each.
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    While I do agree that high gearing can cause overheating, Hende101 is running stock gearing (25/86 or thereabouts ?) and nobody wants to be reducing from stock gearing after going LiPo, when you buy LiPo to you expect more speed not less. So IMO the problem here isn't the stock gearing

    Hende101, are you absolutely sure your gearing is stock ? What about your wheels and tyres, have you changed them ? Bigger overall wheel/tyre sizes are the same as higher gearing. Where are you running your Rustler ? Roads give a small amount of friction but offroad gives more, especially grass if it's not very short. Do you have any binding anywhere in the drivetrain ? Something doesn't sound right IMO

    Buzzforbrains, I'm definitely not having a go or discounting your suggestion, I'm just calling it as I see it

  14. #14
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    I barely changed my bandit vxl ( only replacing broken parts) I haven't changed the gearing I have changed the tyre to a on-road tyres but the same size . I only drive on road. I'm a bit concerned because this is my first lipo and my car/lipo Is playing up!
    Thanks for the help so far

  15. #15
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    While I do agree that high gearing can cause overheating, Hende101 is running stock gearing (25/86 or thereabouts ?) and nobody wants to be reducing from stock gearing after going LiPo, when you buy LiPo to you expect more speed not less. So IMO the problem here isn't the stock gearing
    There are so many variables involved that the stock gearing is not a guarantee for everyone to not over heat. Where you drive, how you drive, ambient temps, weight of the battery and many more all play into it. This is why you need a tmep gun so you can know for sure what the ESC, motor, and battery temps are. Assuming that the stock gearing is safe for all situations is asking for problems.
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    So it's due to over heating right? But it's not usual to happen with my setup ?

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    Yep, I kinda agree Dadx2mj, I've already mentioned driving style, location, temp gun, etc. But IMO the stock gearing is pretty low so to have to gear down when stepping up to LiPo seems counter-intuitive to me, especially as Hende101 has said he is only using it on-road. Of course, I could be wrong, it has happened before lol

    Hende101, it does seem like an overheating issue but the cause is a puzzler for sure. What kind of battery are you using, and what is the C rating ?

  18. #18
    RC Turnbuckle Jr. Petertje60's Avatar
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    For the record: 10.2V is pretty low for cutoff voltage for the VXL-3s on 3S. That is 3.4V per cell. The VXL normally cuts off at a higher voltage.
    Nobody is born with experience

  19. #19
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    My c is 30 mah = 8400 voltage = 11.1 . When should the lvc come in?

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    Heres the link for the battery it might help you:http://www.modelsport.co.uk/black-ma...roducts/371917

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    But fully charged is 3.7v per cell, so surely 3.4v is not low ?

    30C isn't exactly what I'd call all that high either Hende101, I was thinking the problem may have been a very high rate overheating the esc but it doesn't seem that way at 30C. That's quite an expensive battery too so I'd be surprised if there were any faults with it, but you never know. I still think we're all missing the point here tho, or overlooking something or other...

  22. #22
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    This is why I'm confused I'm not sure if it's the low voltage detection or overheating ( this is my first lipo so I could be missing something !)

  23. #23
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    Battery fully charged is 4.2V per cell, not 3.7. It's quite a while ago since I used a VXL-3s, but from what I remember it was always 3.6V per cell or higher what I saw after LVC kicking in. Bear in mind that the actual voltage of the battery is quite lower when the LVC kicks in. It bounces back up quite fast (not more than a few seconds, so you always see a higher voltage when you take it out and measure it.
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    Wouldn't each cell be 3.7 because 11.1 divided by 3 = 3.7 . When should the low voltage detection kick in? ( when it does do I stop or unplug and keep going)

  25. #25
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    Quote Originally Posted by Hende101 View Post
    Wouldn't each cell be 3.7 because 11.1 divided by 3 = 3.7 . When should the low voltage detection kick in? ( when it does do I stop or unplug and keep going)
    3.7V is nominal voltage. Just like a penlight has a 1.5V nominal voltage (it's higher with new ones).

    Low voltage should kick in with a safe margin above 3.0V per cell. Below that voltage, your cells will be damaged.
    If LVC kicks in, the smartest thing to do is charge your battery. 3.6V is pretty normal for the VXL-3s.
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  26. #26
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    So I just went for another run , I charges my lipo to 11.1 then went out after 5 mins it cut out so I went inside and it still had 11 v ( is my lvd to sensitive ?)

  27. #27
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    Quote Originally Posted by Hende101 View Post
    So I just went for another run , I charges my lipo to 11.1 then went out after 5 mins it cut out so I went inside and it still had 11 v ( is my lvd to sensitive ?)
    I wonder how you charge your lipo. You can charge it to 4.2V per cell, that is 12.6V for a 3S. Bear in mind that charging lipo's needs to be done with a charger that is designed to charge lipos.
    Nobody is born with experience

  28. #28
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    Quote Originally Posted by Petertje60 View Post
    I wonder how you charge your lipo. You can charge it to 4.2V per cell, that is 12.6V for a 3S. Bear in mind that charging lipo's needs to be done with a charger that is designed to charge lipos.
    my charger is for lipo's , i won't be using my car for a bit now it seems because i was going at about 1/2 speed when it cut out so i could not break and it went straight into a wall so now a rod has broken which controls the steering to the wheel

  29. #29
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    Do you balance you battery?

  30. #30
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    Quote Originally Posted by JMBEESON View Post
    Do you balance you battery?
    Yes to .01 v

  31. #31
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    10.2v for a 3s is at the level where the low voltage cutoff should kick in. 3.4v per cell x 3 is 10.2.
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    not sure if anyone else mentioned, but your supposed to unplug the battery to turn the car off. not use the esc button. i didnt know this for awhile until i was on the phone with traxxas and the guy told me. my esc would flash red and i couldnt use the button to turn it off either. now i always unplug the batt to power down. what charger do you use? ive got a thunder power ac6 and my 2s lipos charge up to 8.4v. your 3s should charge up to 12.6 and then the charger should stop charging

  33. #33
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    Quote Originally Posted by skmfkr View Post
    not sure if anyone else mentioned, but your supposed to unplug the battery to turn the car off. not use the esc button. i didnt know this for awhile until i was on the phone with traxxas and the guy told me. my esc would flash red and i couldnt use the button to turn it off either. now i always unplug the batt to power down. what charger do you use? I've got a thunder power ac6 and my 2s lips charge up to 8.4v. your 3s should charge up to 12.6 and then the charger should stop charging
    my charger: http://www.modelsport.co.uk/overland...roducts/379060

    I've always unplugged my battery first .
    one last thing, when this does happen what do i do? stop and charge my battery or unplug the battery then plug it in again and keep going?

  34. #34
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    Quote Originally Posted by Hende101 View Post
    my charger: http://www.modelsport.co.uk/overland...roducts/379060

    I've always unplugged my battery first .
    one last thing, when this does happen what do i do? stop and charge my battery or unplug the battery then plug it in again and keep going?
    What I said in post #25: When LVC kicks in, smartest thing is to charge it. When you disconnect and reconnect it, the ESC will notice the voltage bounced back above LVC threshold and it will run again (probably very short). That way you push your lipo to lower voltages than healthy.
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  35. #35
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    Quote Originally Posted by Petertje60 View Post
    What I said in post #25: When LVC kicks in, smartest thing is to charge it. When you disconnect and reconnect it, the ESC will notice the voltage bounced back above LVC threshold and it will run again (probably very short). That way you push your lipo to lower voltages than healthy.
    Ok thanks for your help

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