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Thread: EVX-2 with LVD

  1. #41
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by jamann View Post
    I was curious about that as well..that will warrant some more research I think


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    I've requested the research already. We'll see if my personal lab technician comes through or if he's not worth what I'm paying him.
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  2. #42
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    I just got a new green one with the TQI and LVC built in. The strange part was there was NOTHING in the manual regarding how it functions. There was no supplimental info either. It also came default to LVC was off. So I had to break out my Slash 4x4 manual to remember how to turn on LVC and it worked. I would of been nice to have some instructions with it.

  3. #43
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    Quote Originally Posted by AK49 Traxxas Bashr View Post
    I just got a new green one with the TQI and LVC built in. The strange part was there was NOTHING in the manual regarding how it functions. There was no supplimental info either. It also came default to LVC was off. So I had to break out my Slash 4x4 manual to remember how to turn on LVC and it worked. I would of been nice to have some instructions with it.
    Are you sure it didn't come with a supplemental sheet like this one?
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  4. #44
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    Not real happy with the LVC. It shuts down at 3.5 V which I think is a little high. After it shuts down, the ESC will not work again until you connect a charged LIPO. If you are trying to run a NIMH after the LIPO, you have to deactivate the LVC to run the NIMH. This entails plugging in a charged LIPO to reset it. (I just wait until the LIPO has recovered enough to reset the LVC)

  5. #45
    Marshal ksb51rl's Avatar
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    3.5v/cell at rest? If so, there is no way that is too high.
    You can always turn it off and use a $4 programmable LVA to monitor your LiPo. That's what many of the non-LVD Summit owners do.
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  6. #46
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    I was thinking of going to the evx2 but after the info here ordered a Novak smartstop 2s-4s auto detect. Would of been cool if I started with the new version though.
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  7. #47
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    Quote Originally Posted by ksb51rl View Post
    3.5v/cell at rest? If so, there is no way that is too high.
    You can always turn it off and use a $4 programmable LVA to monitor your LiPo. That's what many of the non-LVD Summit owners do.
    +1

    I for one am tickled pink. I get 40 min from a 5000mah on my p2de before lvc, and if its even close to that efficient for the Summit the majority of people are going to be happy not to be dealing with workarounds. Those that want the extra .2 or so volts are welcome to them.
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  8. #48
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    Quote Originally Posted by ksb51rl View Post
    3.5v/cell at rest? If so, there is no way that is too high.
    You can always turn it off and use a $4 programmable LVA to monitor your LiPo. That's what many of the non-LVD Summit owners do.
    I set mine at 3.5 v a bit of buffer never hurts,i have three sets of batts so the loss of a few minutes of runtime is not a issue for me. Could be for others though


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  9. #49
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    ksb51rl - I didn't see it in my stuff but I will look again. My LVC shut down at 3.8v on my first 2 runs. 7 minutes of run time on 4500mah 2s lipos, thats not good enough. I have a call into Traxxas, gave me a couple of things to try and call them back if I'm still having problems. As always good service from Traxxas, in fact I was surprised I got someone on the phone as late as it was.

  10. #50
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    More battery info please.

    Quote Originally Posted by CrawlinMike View Post
    I was thinking of going to the evx2 but after the info here ordered a Novak smartstop 2s-4s auto detect. Would of been cool if I started with the new version though.
    Bad choice IMO. The SS cuts off at 3.125 volts per cell. This is the reason why the $4 programmable LVA is a much better choice.
    Last edited by ksb51rl; 02-28-2012 at 02:46 PM.
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  11. #51
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    Quote Originally Posted by ksb51rl View Post
    More battery info please.

    Bad choice IMO. The SS cuts off at 3.125 volts per cell. This is the reason why the $4 programmable LVA is a much better choice.
    Ouch. I also have a lva coming I ordered before the Novak SS but it's coming in on the slow boat and I was tired of waiting. On a lighter note the other 3 guys I run with are using the Novak with good results do far. I had no idea it would be set so low. Im not ruining my lipos.WOW. $35 mistake. It'll resell though.
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  12. #52
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    ksb51rl
    ******** 2s 45-90c 4500mah. I run them in my ERBE and get 13-18 minutes on that beast. I has to be an ESC issue.

  13. #53
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    Heck in low gear my kids get 40 minutes or so with nimhs

  14. #54
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    Quote Originally Posted by AK49 Traxxas Bashr View Post
    ksb51rl
    ******** 2s 45-90c 4500mah. I run them in my ERBE and get 13-18 minutes on that beast. I has to be an ESC issue.
    I just got a report from my friend with a new green Summit that "I was able to bash 45 min with the SPC 4700(s) with high/low gearing mix" and "The two batteries that hit lvc last night were very close in voltage this morning." He was off this AM, so he was looking at the packs on a charger, I believe.
    Something is certainly wrong: packs, ESC, or other. If you have an LVA, plug it in and see what is happening to the cells during high amp draws.
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  15. #55
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    Just an update, Traxxas had me pull the motor and ESC and send it to them. Unfortuantly at the time of the phone call they didn't have any of the new ESC's in stock so we will see when I get it back. Guess I can strip it down and dye everything black, I might buy a Monster Mamba to put in it.

  16. #56
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    Quote Originally Posted by xman808 View Post
    I got mine last week and it doesn't have that......guess I got the older model with the newer body.
    I just got mine too, and I also don't have it. So I 2nd that thumbs down!

  17. #57
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    Quote Originally Posted by AK49 Traxxas Bashr View Post
    ksb51rl
    ******** 2s 45-90c 4500mah. I run them in my ERBE and get 13-18 minutes on that beast. I has to be an ESC issue.
    I get about 20-30 with the stock 3000's, and around 45 with the 5000's.

  18. #58
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    This is what happened when I hooked up the Novak 2s-4s auto detect smartstop last night. It was wired right because I tried an xl5 before I changed anything I was so certain I had it right. I searched on here and found its not just me that's had this problem. This smoked as soon as the first battery touched the esc tab. So it's a lva I'll be using from now on if I have an esc without a cutoff already.

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  19. #59
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    Yep, I've said it many times on this forum, the Novak smartstop caused me nothing but problems with both of my Summits. And when I called Novak they said it isn't designed to work with the Summit, but couldn't tell me why.

    I am totally curious how well the Traxxas with LVD functions...
    Bash OR crawl? No, the Summit does it all!

  20. #60
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    power up...

    does anyone know the price to powerup to the lvd, from the original evx2 that came in the summit?

  21. #61
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I do not see any offer for a power up...
    you may be able to do a warranty exchange though.

    The best bet is to call Traxxas.
    Whatever it is I just said... I could be wrong.

  22. #62
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    ok, cool, i'll call them tomorrow.
    thanks

  23. #63
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    So now that the EVX2 with LVD has been out for a while I am wondering how people like it in real world situations?

    Does it monitor both packs, BEC and non BEC sides? (Does that matter?)

    Would it be a good idea to run a pair of LVAs in addition to the built in LVC just to be safe?

    Or as others mentioned just run with LVC disabled and rely on a pair of LVAs to know when to stop? Understanding that's more room for operator error.

    Haven't made the lipo plunge yet, just doing my homework and trying my best to get my ducks in a row.



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    Last edited by happymachinist; 10-21-2012 at 01:23 PM.

  24. #64
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I believe it only monitors the BEC side, as that is the pack that will drain faster.

    Running LVA in addition to the LVD ESC is overkill. I have never read of any ESC's LVD failing.... ever. But, if you feel it is needed, it isn't going to hurt anything.

    In my experience, the EVX2's stage 2 LVD is right around 3.6v/cell.... way more than enough room for error. Actual LiPo cell damage does not occur until 2.5v/cell and safe low voltage is 3v/cell. Since stage 2 completely disables the motor, there is no way to go lower than safe voltage unless you leave your RC on.
    However, since I feel 3.6v/cell is on the high side, I have considered running in NiMh mode with a LVA so I can run it until voltages reach 3.3v/cell. I would only need one due to how I treat my packs... they always get balance charged, balance is checked by my charger and my cell checker before use, and I run my Summit with a BEC so both packs are being drawn from at the same rate.
    Whatever it is I just said... I could be wrong.

  25. #65
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    Quote Originally Posted by Jimmie Neutron View Post
    In my experience, the EVX2's stage 2 LVD is right around 3.6v/cell.... way more than enough room for error. Actual LiPo cell damage does not occur until 2.5v/cell and safe low voltage is 3v/cell.
    Wow, I could not disagree more but I will invite you to run your packs down that low every time you run and report your findings. You seem to be ignoring Depth of Discharge recommendations.

    You have not stated whether the voltage figures you are mentioning are static or under a load. Exactly what are we talking about here? Surely you don't recommend that a person runs a pack down, takes it out, and then measures 2.5v/cell, and everything will be okay? I guarantee some future readers will believe you mean exactly that.
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  26. #66
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It is my understanding that a LiPo should never be drawn below 2.5v/cell... ever... as in 2.5v/cell is absolute zero... as in no matter what the conditions are, the battery should never ever ever be below 2.3v/cell.
    It is also my understanding that 3v/cell is an acceptable, yet rather dangerous, setting for an LVA/LVC. But, due to voltage dip under load the pack would hit 3v/cell; setting off the LVC, then rebound after use to 3.3-3.4. At least this is my experience with the ESC that is in my 16th Revo, as it has a non-adjustable LVC set at 3v/cell.

    I absolutely do not suggest setting the LVA this low if you have any choice in the matter. As a matter of fact, 3.3v/cell would be the lowest I would go... 3.6v/cell would be even better for those that do not take very good care of their LiPo's. I actually have my buddies ESC set to go off at 3.8v/cell because of the simple fact that he has the habit of just leaving the RC sit for a few days after a run.... not even thinking to charge the LiPo's back up to storage voltage.
    Whatever it is I just said... I could be wrong.

  27. #67
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    Quote Originally Posted by rclipotesting
    Discharging :

    Never over discharge a cell/pack. This is one of the major causes of damage to a cell/pack. The majority of speed controls on the market have a built in LiPo cut off make sure it's enabled. If the cutoff is adjustable I recommend that it be set at 3.4V per cell minimum. Some speed controls require that a link cable be purchased which allows the speed control to be hooked up to a PC and be adjusted. If none of these options are available or if your speed control has no cut off you need to try and find the point at which your pack is getting to low in voltage and stop. You can do this by running it for a certain amount of time then checking the voltage of the pack. If the voltage is lower than 3.5V per cell than you have run the pack to low. If you run the pack and notice the power is dropping stop immediately as you have run the pack to low. You can measure the voltage of the pack and you will notice it's below 3.5V per cell. The above method will help you determine a rough idea of how much time you can run the pack before it gets too low.

    To get maximum cycle life out of your packs you should set the cut off on the high side. Cycle life is greatly increased if a cell/pack isn't discharged below 80% of its capacity. This is referred as Depth of Discharge (DOD). Unfortunately the speed control manufacturers didn't take this into account when designing there systems to be used with LiPo packs. If your speed control is set at 3V or 3.2V per cell which seems to be the common voltage used as default in most speed controls this will result in 99% and 98% DOD. By increasing the cut off to 3.4V per cell the DOD will be 96%. If 3.6V is used this will result in 85% DOD. These calculations are provided by info gathered on testing equipment which is calibrated to compensate for voltage drop. The DOD will fluctuate based on a cell/packs resistance and the discharge load being pulled from the cell/pack. A motor which pulls less amps will discharge a pack more as there will be less voltage drop. It's up to you to determine if you want maximum play time or maximum cycle life. The info above is intended to help you make this decision.
    I follow the above instructions.
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  28. #68
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Thanks for the info, KSB!!
    Whatever it is I just said... I could be wrong.

  29. #69
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    Then when the time comes I will rely on the built in LVC of my EVX2. It may be set higher than some prefer but they are undoubtedly more experienced than myself.

    I generally tend to error towards the side of caution. If its a matter of a few extra minutes of run time vs ruining a pair of $65 batteries or getting more cycles on those packs I'll gladly pause the fun for a quick battery change.

    Thanks for the input guys. There will probably be more questions to come.


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    Last edited by happymachinist; 10-22-2012 at 12:23 AM.

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    Double Post

  31. #71
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    I know this is somewhat of an older thread but ak49 what ended up happening with your issue??? My evx-2 with lvd is cutting power somewhere around 7.88 volts on my spc lipos in my summit. Seems kinda high??? Anyone else notice what there are cutting out at???

  32. #72
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    Also forgot to mention they are 2s packs so that would be 3.94 per cell. And that was running it for another few minutes in high gear and checking the voltage within a few minutes of disconnecting them from the truck.

  33. #73
    jonesdallas
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    Ya, I`m experiencing the same thing, I have stock electronics with SPC 8200 50c. My LVD trips super early between 3.9-4.1. To me I guess Traxxas is being an over protective parent LoL, Which is not the worst thing. But Ive switched to running my lipos with LVD OFF and monitoring the cells. I will be picking up a programable LVD this weekend, probably going to use 3.3 as my setting.

    I also plan on putting in a tekin system soon, So I will be sending the ESC back to Traxxas to take a look at it when its no longer being used.

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