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Thread: Is this battery

  1. #1
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    Is this battery

    Safe to use? Just noticed it this weekend, it's been stored for about 2 months. I charged to storage capacity before putting it away.

    It's a Traxxas 2S, 25C, 7600

    Thanks in advance.


  2. #2
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It seems slightly puffed to me.

    Where was it stored?
    What it the cell voltage currently?
    Whatever it is I just said... I could be wrong.

  3. #3
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    7.6V. Stored in a lipo bag in a fireproof box at room temp.

  4. #4
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    What is cell voltage? We can assume 3.8v/cell... but it is safer to take assumptions out of the equation.

    How old is the pack?
    Roughly how many cycles?
    Ever over discharged or charged?
    Always balance charged?
    Whatever it is I just said... I could be wrong.

  5. #5
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    3.851, 3.839
    ~ 1 year
    ~ 20
    No. ESC (CC SCT) set to lipo shut off.
    Onyx 235 Set to battery specs, always use balance.

  6. #6
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It should be fine from all the info you gave me, but it doesn't look fine. lol

    Any more pictures of it?
    Whatever it is I just said... I could be wrong.

  7. #7
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    It looks a bit more dramatic in person.... If it matters the bulging part is soft, reminds me of a bubble under a decal.




    Thanks for you input.

  8. #8
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It is most definitely puffed... I wouldn't use it.

    Call Traxxas... let them know what is going on. Worst case scenario is you pay 50% off retail for one under the Traxxas warranty.
    Whatever it is I just said... I could be wrong.

  9. #9
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    OK Thanks.

    I ordered it from A Main on 2-14-13, will try them first.

  10. #10
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    Since the pack appears to be puffed both top and bottom, this means it was subjected to something it did not like - and I would bet the pack was over-discharged as this is what almost always causes a problem as noted in the photos.

  11. #11
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    How can that be avoided, the car auto shuts down when the battery gets low. The esc is set to default values. also, I treat both batteries the same, and the other one is showing no bulges.

    Thanks for the reply.

  12. #12
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    I believe the default LVC setting for the Castle ESC is 3.2 volts per cell, which in my experience has proven to be borderline too low. Also, we all assume that the LVC set points are 100% accurate and that when the pack reaches exactly 6.4 volts total the ESC shuts down. When in fact the LVC set point can vary somewhat due to typical QC. I am in no way saying this is for certain in your case, nor am I saying Castle ESC's are faulty or Castle makes a bad product, rather I am just pointing out one possible way for the pack to be over-discharged.

    Did you ever run the pack down to the LVC set point and leave it connected to the ESC for a length of time? Say for the afternoon or evening?

    Was the pack ever (even just once) run down to the LVC set point and not recharged for some period of time, again say over night or a little longer?

    What was the longest period of time the pack ever sat unused?

    Many things can contribute to a over-discharged pack.

  13. #13
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    Quote Originally Posted by Jakey View Post
    I believe the default LVC setting for the Castle ESC is 3.2 volts per cell, which in my experience has proven to be borderline too low. Also, we all assume that the LVC set points are 100% accurate and that when the pack reaches exactly 6.4 volts total the ESC shuts down. When in fact the LVC set point can vary somewhat due to typical QC. I am in no way saying this is for certain in your case, nor am I saying Castle ESC's are faulty or Castle makes a bad product, rather I am just pointing out one possible way for the pack to be over-discharged.

    Did you ever run the pack down to the LVC set point and leave it connected to the ESC for a length of time? Say for the afternoon or evening?

    Was the pack ever (even just once) run down to the LVC set point and not recharged for some period of time, again say over night or a little longer?

    What was the longest period of time the pack ever sat unused?

    Many things can contribute to a over-discharged pack.
    No - always un plugged. Had a hot battery ready to go do some more bashing.
    Yes - before I knew about storage voltage. But this is the case with the other battery as well. I also stored them fully charged before I found out that was a no-no. Usually due to carnage at the first of the run.
    As stated above - a couple of months 2 to maybe 3.
    I will go into the castle link and change the LVC setting - suggestions?
    I'm a LiPo newb, still learning.

  14. #14
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    Mine are at 3.5 volts

  15. #15
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    Quote Originally Posted by rcnewbie1234 View Post
    Mine are at 3.5 volts
    Thanks for the reply. Sounds like a good starting point.

  16. #16
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    Quote Originally Posted by HowardTheDuck View Post
    No - always un plugged. Had a hot battery ready to go do some more bashing.
    Yes - before I knew about storage voltage. But this is the case with the other battery as well. I also stored them fully charged before I found out that was a no-no. Usually due to carnage at the first of the run.
    As stated above - a couple of months 2 to maybe 3.
    I will go into the castle link and change the LVC setting - suggestions?
    I'm a LiPo newb, still learning.
    I cannot explain why one pack failed yet the other still appears fine. It could be due to some very small difference in the way the packs were operated, maybe even one particular event that was ever so slightly different between the two packs. So insignificant in difference that the operator never noticed it all. Or the other pack still appears fine because you just got lucky.

    I have personally full-cycle, lab tested RC packs numbering well into several thousand and this includes more than 1,000 LiPo packs, and I will honestly (humbly) say I am still learning. Virtually every question I asked you and every point I made about LiPo failures came from my own testing and/or use of packs. Trust me when I tell you this .... I have killed a lot of RC LiPo packs over the past 6 years and each one of these pack deaths has taught me something about the mechanisms of pack failures. Sadly for a new user, it is almost common for the first pack to suffer as part of the overall learning process, but after that the user says; "Oh yeah, now I get it.", and they go on to operate the next pack(s) for hundreds of good cycles.

    Set the LVC to at least 3.4 volts per cell, even 3.5 volts per cell to be safer. Overall you will not lose 1 to 2 minutes of runtime during a typical run, but this higher LVC setting will make the pack much happier during the long term life of the pack.
    Last edited by Jakey; 01-06-2014 at 01:00 PM.

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