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  1. #1
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    Can't trust the LVC on the VXL-8s

    I had called Traxxas to inquire as to what the LVC was set at and the answer was approximately 3.7-3.8.
    Well after my 4th set of packs thru I decided to test them as soon as the truck went into the limp mode.
    These are brand new SMC 4s 7400 packs. the pack on the passenger side (connected to the red esc wire) was a bit low, in the 3.4-3.6 range but the drivers side (connected to the black esc wire) had cells 1&3 at 2.89 & 2.83 , cells 2&4 were 3.16 & 3.55 .

    Disturbing to say the least.

    I have just ordered a couple of audible alarms to plug into the balance leads and I will mount them on the tray tops somehow.

    I did also get the Bluetooth so I could monitor the temps and voltages on my phone but the app sucks and keeps shutting down. That was a waste of 30$.

    I love the telemetry on my Flysky,

  2. #2
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    The batteries are in series. If 1 pack is that much lower than the other, I would look at the low pack as the problem. My smc packs both are around 3.5v/cell after a run after hitting lvc on the vxl8s ESC when they are at resting voltage after the run. Looks like u have a sub standard smc pack. Contact them


    I believe the vxl escs are set to 3.3v/cell lvc. This will leave them around 3.4 to 3.6v per cell when at resting voltage.
    Last edited by rag6; 03-16-2018 at 12:45 AM.
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  3. #3
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    yeah the esc just measures the total voltage of both packs together and not every single cell. so if there is a "bad" pack, not similar packs or a bad cell this will not be detected of course.
    Exercitatio artem paravit

  4. #4
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    I have been in contact with SMC even before I got the batteries in the mail and his suggestion (Danny at SMC ) was that because they are in series that I should rotate the packs after every full charge so they will get equal use over time.

    Also looking back at my OP, I have realized that I forgot to include a possible / probable factor. I had 2 LED strips hooked into the ballance wire harness on the low pack. I sure didn't think that they would affect the battery that much but I won't do that again. I have a small footprint 3s 1500mAh battery coming to supply the LEDs.

  5. #5
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    I guess If the esc was set at 3.3 then it works out as an average. BUT that is still to low for me. Why oh why can't they put some options on the Link System?

    I really like all of my Traxxas vehicles but they all have one thing in common, they all walk the fine line between hobby grade and toy grade.
    For the Teton that I run around my living room, toy grade is fine but a thousand dollar X Maxx should be in a different class and have been thought out a bit more.

  6. #6
    RC Champion NYbandit33's Avatar
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    Quote Originally Posted by 8000ft View Post
    Why oh why can't they put some options on the Link System?
    I dont believe you can change the LVD cutoff (someone please tell me if you can) but you can set alerts in the app that will notify you when the battery voltage drops below a certain point
    Monster Baja Sla2h VXL
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  7. #7
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    Use this : LVA (Lipo Battery Low Voltage Tester VOLTMETRE monitor Buzzer alarm )


  8. #8
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    Quote Originally Posted by 8000ft View Post
    I had called Traxxas to inquire as to what the LVC was set at and the answer was approximately 3.7-3.8.
    Well after my 4th set of packs thru I decided to test them as soon as the truck went into the limp mode.
    These are brand new SMC 4s 7400 packs. the pack on the passenger side (connected to the red esc wire) was a bit low, in the 3.4-3.6 range but the drivers side (connected to the black esc wire) had cells 1&3 at 2.89 & 2.83 , cells 2&4 were 3.16 & 3.55 .

    Disturbing to say the least.

    I have just ordered a couple of audible alarms to plug into the balance leads and I will mount them on the tray tops somehow.

    I did also get the Bluetooth so I could monitor the temps and voltages on my phone but the app sucks and keeps shutting down. That was a waste of 30$.

    I love the telemetry on my Flysky,
    My last run I had a similar issue with my stock vxl8s esc well see next run out.

  9. #9
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    Quote Originally Posted by NYbandit33 View Post
    I dont believe you can change the LVD cutoff (someone please tell me if you can) but you can set alerts in the app that will notify you when the battery voltage drops below a certain point
    There is no way to do it on our own. I was wishing that the Link App could be designed to allow us to adjust the LVC.
    I did set up the Link alarms but it doesn't work if the stupid app keep shutting itself off. Which mine does almost every time. Even if it did work , I don't have the mount on my radio to hold my phone so it is pretty much useless any way.

  10. #10
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    Quote Originally Posted by zeflex View Post
    Use this : LVA (Lipo Battery Low Voltage Tester VOLTMETRE monitor Buzzer alarm )

    yep, just ordered a 4 pack. I will Velcro 2 of them to the battery holder area. and 2 for when the water destroys the first 2

  11. #11
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    Quote Originally Posted by 8000ft View Post
    I had called Traxxas to inquire as to what the LVC was set at and the answer was approximately 3.7-3.8.
    Well after my 4th set of packs thru I decided to test them as soon as the truck went into the limp mode.
    These are brand new SMC 4s 7400 packs. the pack on the passenger side (connected to the red esc wire) was a bit low, in the 3.4-3.6 range but the drivers side (connected to the black esc wire) had cells 1&3 at 2.89 & 2.83 , cells 2&4 were 3.16 & 3.55 .

    Disturbing to say the least.

    I have just ordered a couple of audible alarms to plug into the balance leads and I will mount them on the tray tops somehow.

    I did also get the Bluetooth so I could monitor the temps and voltages on my phone but the app sucks and keeps shutting down. That was a waste of 30$.

    I love the telemetry on my Flysky,
    I have the exact same issue on the VXL-6 in the new Erevo 2.0. !!!Also ALWAYS the lipo in the left, with the plug that has both black wires attached. Even when I alternate packs, it happens to the one on that side. Not happy. I set my LVC in my old Revo to 3.4V and never had this happen. Will replace this piece of trash Traxxas ESC with another Mamba Monster 2.


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  12. #12
    RC Champion NYbandit33's Avatar
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    Quote Originally Posted by 8000ft View Post
    There is no way to do it on our own. I was wishing that the Link App could be designed to allow us to adjust the LVC.
    I did set up the Link alarms but it doesn't work if the stupid app keep shutting itself off. Which mine does almost every time. Even if it did work , I don't have the mount on my radio to hold my phone so it is pretty much useless any way.
    What device are you using to run the app? It works fine on my iphone but Ive heard people with samsung devices having trouble. I plan on getting the phone holder soon but right now i keep the phone propped on the trunk of my car.
    Monster Baja Sla2h VXL
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  13. #13
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    Quote Originally Posted by 8000ft View Post
    yep, just ordered a 4 pack. I will Velcro 2 of them to the battery holder area. and 2 for when the water destroys the first 2
    Put them in small plastic bags and nice transparent adhesive and they will be almost waterproof. I can send you a picture of what I did to mine.

  14. #14
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    Do you guys running the app is your volt gauge accurate? I set it up tonight after a run and the volt gauge was showing 6volts,I changed the alarm to 21.8v but the gauge still showed 6volts.turned it all off and checked the batteries with a volt meter and both were at 11.27v.fired everything back up and app still showed 6v,WTH!?! I got the app just to be able to monitor batteries,what a waste.

  15. #15
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    You have to tap on the screen when you have your dashboard up and add a new gauge snappyxmaxx.

  16. #16
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    Know your voltage
    Best to stop running before lvc
    Keep your batteries balanced before each run -after charge - when in storage
    Use a Astro Flight Blinky Balancer or similar, before and after charging
    fabricator

  17. #17
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    Quote Originally Posted by NYbandit33 View Post
    What device are you using to run the app? It works fine on my iphone but Ive heard people with samsung devices having trouble. I plan on getting the phone holder soon but right now i keep the phone propped on the trunk of my car.
    yep, Samsung s5

  18. #18
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    Quote Originally Posted by CrazyXMAXX View Post
    Know your voltage
    Best to stop running before lvc
    Keep your batteries balanced before each run -after charge - when in storage
    Use a Astro Flight Blinky Balancer or similar, before and after charging
    um good info...nuf said...

  19. #19
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    I have the exact same issue on the VXL-6 in the new Erevo 2.0. !!!Also ALWAYS the lipo in the left, with the plug that has both black wires attached. Even when I alternate packs, it happens to the one on that side. Not happy. I set my LVC in my old Revo to 3.4V and never had this happen. Will replace this piece of trash Traxxas ESC with another Mamba Monster 2.
    ? sorry but that would really be absolutely strange and not logical at all. the esc takes the battery packs in series as one pack. the esc (also the mamba monster) only checks to the total voltage of the whole pack. if total voltage drops below the cut off it stops. of course that total voltage does not mean every single cell in the pack is on the same voltage. there could be huge difference for instance if you have one bad cell in the pack. but that the esc systematically should "draw" somehow more amps from just one cell would be kinda of "magic". how should that work?
    Last edited by rhylsadar; 03-17-2018 at 09:43 AM.
    Exercitatio artem paravit

  20. #20
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    Quote Originally Posted by SnappyxMaxx View Post
    Do you guys running the app is your volt gauge accurate? I set it up tonight after a run and the volt gauge was showing 6volts,I changed the alarm to 21.8v but the gauge still showed 6volts.turned it all off and checked the batteries with a volt meter and both were at 11.27v.fired everything back up and app still showed 6v,WTH!?! I got the app just to be able to monitor batteries,what a waste.
    This will not prevent an inaccurate read of each cells, it mesure the whole batteries voltage.

    In your receiver, you have the temperature sensor plugged to a red connector. This connector is plugged onto the receiver that's why you see 6v. This red connector instead should be wired to the + of your esc.

    Check the single red wire/connector coming from the esc.


  21. #21
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    Quote Originally Posted by zeflex View Post
    This will not prevent an inaccurate read of each cells, it mesure the whole batteries voltage.

    In your receiver, you have the temperature sensor plugged to a red connector. This connector is plugged onto the receiver that's why you see 6v. This red connector instead should be wired to the + of your esc.

    Check the single red wire/connector coming from the esc.

    won't that feed full battery voltage to the Rx?
    I have an RC problem...

  22. #22
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    No, the red single connector of the esc should be plugged to thie red connector of this :



    And the grey connector of the temperature sensor to the rx telemetry.

  23. #23
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    Some details:


  24. #24
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    Quote Originally Posted by rhylsadar View Post
    ? sorry but that would really be absolutely strange and not logical at all. the esc takes the battery packs in series as one pack. the esc (also the mamba monster) only checks to the total voltage of the whole pack. if total voltage drops below the cut off it stops. of course that total voltage does not mean every single cell in the pack is on the same voltage. there could be huge difference for instance if you have one bad cell in the pack. but that the esc systematically should "draw" somehow more amps from just one cell would be kinda of "magic". how should that work?
    I don’t know how it happens. Today I swapped the packs. A brandnew ones I bought yesterday and the exact same thing happened!!! 1st cell, left battery just below 3.0V!!!🤯


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  25. #25
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    Quote Originally Posted by dronenewbie View Post
    I don’t know how it happens. Today I swapped the packs. A brandnew ones I bought yesterday and the exact same thing happened!!! 1st cell, left battery just below 3.0V!!!��


    Sent from my iPhone using Tapatalk
    This is strange, but I have seen similar results with other ESCs as well. One cell finishing up significantly lower than the others. I usually compare the internal resistance across the cells, and in most cases, they have been extremely matched! It does come down to the lvc being set too low. High discharge batteries give their capacity away freely, and if taken too close to minimum voltage, one cell often suffers. Just my observations...

  26. #26
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    yeah but that would be caused by the cells in the pack not being equal. but that has nothing to do with the esc. if one cell is bad it would be bad on ANY esc.


    I don’t know how it happens. Today I swapped the packs. A brandnew ones I bought yesterday and the exact same thing happened!!! 1st cell, left battery just below 3.0V!!!
    still. it might just be some form of random coincidence or something. if you can replicate that result with different battery packs and repeatedly then you should really film it with battery checkers etc. that would be some kind of... don't know how to call it.
    Last edited by rhylsadar; 03-17-2018 at 01:04 PM.
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  27. #27
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    Quote Originally Posted by NYbandit33 View Post
    What device are you using to run the app? It works fine on my iphone but Ive heard people with samsung devices having trouble. I plan on getting the phone holder soon but right now i keep the phone propped on the trunk of my car.
    Quote Originally Posted by 8000ft View Post
    I did also get the Bluetooth so I could monitor the temps and voltages on my phone but the app sucks and keeps shutting down. That was a waste of 30$.
    I use app on old Samsung S3 phone and works just fine. Its easy to mount to tx, just go to walgreens or walmart and buy a $7 arm band for phone or ipod and put it in the pouch, make band tight with phone against batt cover then flip or twist it up around side of base so it sits like pictured. Check your phone settings. Maybe if you have power saver mode on it shuts down apps after certain time. Choose settings that leave open app on.

    I have not experienced lv issues on batts with my SMC 4s's and run speed gearing in my 8s Snap On edition for bashing and street running. The lv alarms are the best way to know exactly whats going on with batt volts. I use them on my Rustler speed runner and work like a charm. As mentioned Id definitely lock them down somehow, Ive had them come off speed runner before.

    I need just one more rc, then Im done,
    Last edited by Briber; 03-18-2018 at 12:46 AM.
    Just need one more rc, then Ill be done...

  28. #28
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    Quote Originally Posted by Briber View Post
    I use app on old Samsung S3 phone and works just fine. Its easy to mount to tx, just go to walgreens or walmart and buy a $7 arm band for phone or ipod and put it in the pouch, make band tight with phone against batt cover then flip or twist it up around side of base so it sits like pictured. Check your phone settings. Maybe if you have power saver mode on it shuts down apps after certain time. Choose settings that leave open app on.

    I have not experienced lv issues on batts with my SMC 4s's and run speed gearing in my 8s Snap On edition for bashing and street running. The lv alarms are the best way to know exactly whats going on with batt volts. I use them on my Rustler speed runner and work like a charm. As mentioned Id definitely lock them down somehow, Ive had them come off speed runner before.

    I need just one more rc, then Im done,

    Okay now I feel really stupid.......why didn't I think of the runners phone case. Brilliant sir, thank you.

  29. #29
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    Quote Originally Posted by dronenewbie View Post
    I don’t know how it happens. Today I swapped the packs. A brandnew ones I bought yesterday and the exact same thing happened!!! 1st cell, left battery just below 3.0V!!!��


    Sent from my iPhone using Tapatalk
    by 'left one' do you mean the drivers side? (USA drivers side that is) and is this the one that is plugged into the black (negative) wire coming from the ESC?
    If so then it make perfect sense. In DC electronics the actual electrons flow from the negative side of the battery to the positive side therefore the pack connected to the negative lead will send it's electrons thru the entire other battery ( Electrons out of the left battery thru the negative wire and into the right positive wire and then out it's negative wire) so the right battery will always have just a bit more juice in to than the other. And by a bit you have to remember that we are measuring these battery's in tenths and hundredths of volts....

  30. #30
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    Quote Originally Posted by 8000ft View Post
    by 'left one' do you mean the drivers side? (USA drivers side that is) and is this the one that is plugged into the black (negative) wire coming from the ESC?
    If so then it make perfect sense. In DC electronics the actual electrons flow from the negative side of the battery to the positive side therefore the pack connected to the negative lead will send it's electrons thru the entire other battery ( Electrons out of the left battery thru the negative wire and into the right positive wire and then out it's negative wire) so the right battery will always have just a bit more juice in to than the other. And by a bit you have to remember that we are measuring these battery's in tenths and hundredths of volts....
    Thank you sir, I finally a “scientific” answer just not “It’s not possible” or I’m making things up. Yes, it’s always been the first cell in the pack on the USA driver’s side, connected to the negative side. Anyway, got rid of that crappy esc today and replaced it with a MM2 and guess what? No issues. Left (USA driver’s side) pack had a bit lower cell voltage than the other, but nothing to be concerned about. All is good now. Traxxas will probably come out with an update sooner or later but since I run an aftermarket radio I can’t take advantage if it.


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  31. #31
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    It will still be lower that the other regardless of the ESC, it just the way batteries in series work.

    I have a little reusable zip-tie that is attached to the rear of the front shock tower, where those 2 1/4" holes are. I use it to mark which side my "A" pack was used last time , yes I labeled my packs A & B. After a fresh charge I will swap them back and forth and marking which side is my "A" pack.

  32. #32
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    Quote Originally Posted by 8000ft View Post
    Okay now I feel really stupid.......why didn't I think of the runners phone case. Brilliant sir, thank you.
    Your most welcome. Btw, me stupid too! I had this really heavy bulky metal contraption bolted to top of TX until one day wife brought home the arm band and said try this. So I cant take credit for it, it was actually my smart wife that came up with idea lmbo!!!

    I need just one more rc, then Im done,
    Just need one more rc, then Ill be done...

  33. #33
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    It will still be lower that the other regardless of the ESC, it just the way batteries in series work.
    if you're explaination is correct that is exactly the point several people have made above: that little differences would have nothing to do with the esc. it would just be a general phenomenon that batteries would suffer a little when connected in series.

    therefore that "conclusion":
    got rid of that crappy esc today
    makes still no sense.

    i would still be interested to see the real cause of this "problem". maybe it was just a flaw in your esc. it seems not to be a general issue at all.
    Last edited by rhylsadar; 03-19-2018 at 03:59 AM.
    Exercitatio artem paravit

  34. #34
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    Quote Originally Posted by rhylsadar View Post
    if you're explaination is correct that is exactly the point several people have made above: that little differences would have nothing to do with the esc. it would just be a general phenomenon that batteries would suffer a little when connected in series.

    therefore that "conclusion":
    makes still no sense.

    i would still be interested to see the real cause of this "problem". maybe it was just a flaw in your esc. it seems not to be a general issue at all.
    Well, this reply makes perfect sense to me, especially since the cell it always happens too is the very first one on the neg. wire.


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  35. #35
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    have you read the next post from the the author of that post?

    It will still be lower that the other regardless of the ESC, it just the way batteries in series work.
    what he is describing is a general functioning of any batteries connected in series and will happen on any esc.
    his point is interesting and i will surely have an eye on that this season.

    however that offers no explanation for your "issue" that it will only happen on the trx esc. so we still have a puzzle there.
    Exercitatio artem paravit

  36. #36
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    Quote Originally Posted by rhylsadar View Post
    what he is describing is a general functioning of any batteries connected in series and will happen on any esc.
    his point is interesting and i will surely have an eye on that this season.
    Yes, it will happen with any esc which low voltage cutoff is set way too low. And nobody can tell me what that value on the stock esc is. On my new one I set it to 3.4V (3.4x 6=20.4V) maybe stock setting on VXL is 18V? That would explain the issue.


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  37. #37
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    that is an interesting point. if the lvc is set too low that might intensify the issue with the "low voltage" first cell.

    interestingly this thread was started with a statement that the lvc on the trx esc would be set quite high. however that would correspond to the vxl8s.

    I had called Traxxas to inquire as to what the LVC was set at and the answer was approximately 3.7-3.8.
    i would be a very useful information where the lvc (or low voltage detection lvd as trx calls it) is set as a default on those two esc vxl8s and the new vxl6s.
    Exercitatio artem paravit

  38. #38
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    Update,
    Well since my original screw-up which I am now taking responsibility for, I have not run the LED's and have kept a very close eye on my voltage on the Link (when it is working...) or with a plug in tester and have quit when the link shows a combined voltage of 30.0 or 15.0 per side with the plug in. This gives an average of 3.75V per cell. Now when I plug in the SMC's into the dual charger they are reading surprisingly close beginning numbers, like within a hundredth or 2 of each other.
    The really good news about this is that there doesn't seem to be any damage to them from the dreadfully low readings that I got that one and only time....whew.

  39. #39
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    There is no doubt that with greater depth of discharge, the cell voltages will diverge, sometimes alarmingly. You shouldn’t see much of that if an LVC is set to 3.5 Volts per cell, but at the extremely low cell voltage levels being discussed here and elsewhere in the forum, large divergences are more of a routine occurrence than a singular oddity.
    Alt-248 on the number pad = °

  40. #40
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    Everybody desperately needs to purchase the Bluetooth module and upgrade the ESC firmware. My very old SMC's came off around 3.7 after resting with very good run times.
    And also, Samsung and Android users, do not try using the "gauge cluster" in the Traxxas app dashboard. Change it to grid mode and try it. Works great for me now. You can set all alarms where you want and set maximums and/or minimums for all gauges. You can hear the voltage alarm going off when it dips below alarm when you punch the throttle.

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