Results 1 to 22 of 22
  1. #1
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969

    How can 1 of 2 lipos puff?

    I was reading through alot of lipo posts, but couldnt really find an answer to my question

    I did end up getting some 4s SMC lipos, but after only a few runs, 1 is slightly bigger than the other. Both were always run and charged together, never even close to the LVC, stored at 3.85, charged at 6A. The cells are balanced for both.

    If i treated both with the same amount of care, Does anyone know how it could be that one has zero puffing yet the other is starting to?

  2. #2
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    It could be 1 weak cell in one battery pack. Usually, If only 1 cell puffs(out of 4 in a 4s pack) either that cell was not balanced correctly, and it was damaged by over discharge or over charge, OR, it might be a defective cell.

    If all 4 cells (within that 4s pack)puff at same time, it's almost always user error, or a bad charger incorrectly charging the pack.

    You can check the accuracy of your chargers balance circuit with a volt meter. After you balance the pack, note each cells individual cell voltage (resting voltage, not while charging), then check each cell with the volt meter to see if the charger is reading correctly.

    Being that only 1 pack has puffed, it's prob not the charger, but I test my chargers accuracy every once in a while, as I had a charger go bad and ruin 3 packs in the past.

    Contact the battery manufacturer. I hope you have better luck with smc than I did. I will not trust their "warranty" or their customer service ever again. To be fair, I have had mostly very good packs from them, but it only takes getting screwed over on a defective 50$ pack 1 time to make me cautious.

    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

  3. #3
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    thanks. its been a long time since ive seen a puffed battery so im not sure if its one cell or not. the bottom of the pack is indeed flat, but the top is bigger. I can depress the top of the pack where the puff is, so i dont know if thats just air or if a truly puffed battery is supposed to be firm when puffed.

    i guess ill reach out to where i bought them and see what they can do. i agree i dont think its user error in this case as i treated both the same .

  4. #4
    RC Competitor
    Join Date
    May 2020
    Posts
    84
    I use a battery checker that gives me a per cell reading.
    I also use a charger that will report the cells internal resistance.
    I like to check these right away on new batteries. ( I neglected to on my new traxxas batteries

    Most batteries get a tail light warranty, I hope they take care of you.. buggers are pricey.

  5. #5
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    my charger can check resistance. what would i be looking for? i think i have to charge them up fully first though, hopefully that is okay...

  6. #6
    RC Racer
    Join Date
    Nov 2019
    Posts
    100
    My personal rule of thumb on my 4S FPV quad packs (1300-1700 mAh) is to look for any resistances higher than 20 milliohms. lower than 10 is what I would consider "good", 10-20 fair but degraded and over 20 is time to dispose. (of course this depends on the total capacity of the packs) Equally important is to look for any cells that diverge significantly from the rest. I'm not sure where RC car packs should be since I've only been back in land-based RC for a short time now. Perhaps one of the longer members here can give a better answer.

    Here is a reading from one of my good 1300 mAh packs: 8, 8, 9, 8 mΩ.
    Reading from one of my X-Maxx's newish 4S, 5200 mAh packs: 2, 2, 2, 3 mΩ.
    And here is a reading from a well-worn 4S pack that I mistakenly left fully charged for a year: 27, 8, 8, 9 mΩ.



    *Readings were all taken via a Hitec X2 AC Plus charger.


    *Please see point #12. Properly dispose of packs please.
    Last edited by Double G; 08-08-2020 at 08:55 AM.

  7. #7
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    The readings directly above^^^^ mirror my experience with both small and large capacity packs. My mini packs we're usually around 10, and my standard size 5000 ish packs were always around 3 milliohms. As you can see in his damaged pack, the 1 cell is shot and the other 3 are weak.

    Newer chargers are really helping us hobbyists in diagnosing and evaluating the electrical side of our machines. My ToolkitRC M8s is pretty amazing
    https://youtu.be/qAHBGW17uNY
    My favorite feature is it can individually calibrate input and output values on everything. You can be 100% sure your charger is perfect. I would suggest chargers with these features to anyone who wants to get deeper into the hobby after their 1st car. It really is worth the extra 20-40$ to get 5x the power and capability.



    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

  8. #8
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    Oops, another cause to make 1 cell puffs is crash damage. I don't think it was mentioned if your packs have had any impacts?

    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

  9. #9
    RC Champion
    Join Date
    Feb 2020
    Location
    Canary Islands, Tenerife, Spain.
    Posts
    1,349
    The fail possibiliity always exist.

  10. #10
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    i dont know, maybe its a false alarm? i did a full charge today and the cells balanced fine at 4.20. the resistance for each battery was below in the links. the 1 battery is still definitely larger than the other though.

    i ran it today and it was fine as usual and when i stopped all 8 cells were fine at 3.9v

    i guess maybe it is possible for a little expansion even for batterys that are balancing fine?

    https://ibb.co/DGjzR5D
    https://ibb.co/GR64BWT

  11. #11
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    A battery expanding like that is an issue. Period. Don't turn your back on it.

    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

  12. #12
    RC poster
    Join Date
    Dec 2019
    Location
    North Carolina
    Posts
    5
    I recently had the same exact issue. Pair of 4s SMC batteries, well taken care of since I bought the xmaxx last December. One is slightly puffed and the other is fine! Can’t hardly close the battery tray on the puffed one. Still charges and balances perfectly but I keep a close eye on it when charging. Thing is a beast though, always attracting attention.

  13. #13
    RC Champion grizzly03's Avatar
    Join Date
    Dec 2014
    Location
    Adirondacks
    Posts
    2,261
    Here is an article written by SMC. It has a section about LiPo cells swelling or puffing.
    rctruckstop.com/2019/09/25/expert-answers-on-lipo-batteries

  14. #14
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    nice article, thanks for posting. I feel a bit better when they say " If a cell or pack has some expansion itís still fine to use the pack as long as the cells are charging properly and in balance."

  15. #15
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    Quote Originally Posted by EnormousMaximus View Post
    I recently had the same exact issue. Pair of 4s SMC batteries, well taken care of since I bought the xmaxx last December. One is slightly puffed and the other is fine! Can’t hardly close the battery tray on the puffed one. Still charges and balances perfectly but I keep a close eye on it when charging. Thing is a beast though, always attracting attention.
    very interesting and very similar to my situation too. how many runs or charges have you run with the puffed one?

  16. #16
    RC Champion
    Join Date
    Feb 2020
    Location
    Canary Islands, Tenerife, Spain.
    Posts
    1,349
    Quote Originally Posted by grizzly03 View Post
    Here is an article written by SMC. It has a section about LiPo cells swelling or puffing.
    rctruckstop.com/2019/09/25/expert-answers-on-lipo-batteries
    Very interesting, thanks for the link.

  17. #17
    RC Champion
    Join Date
    Feb 2020
    Location
    Canary Islands, Tenerife, Spain.
    Posts
    1,349
    Quote Originally Posted by varunaX View Post
    i dont know, maybe its a false alarm? i did a full charge today and the cells balanced fine at 4.20. the resistance for each battery was below in the links. the 1 battery is still definitely larger than the other though.

    i ran it today and it was fine as usual and when i stopped all 8 cells were fine at 3.9v

    i guess maybe it is possible for a little expansion even for batterys that are balancing fine?

    https://ibb.co/DGjzR5D
    https://ibb.co/GR64BWT
    Sometimes this puffing can be normal, anyway, check the battery status each time.

  18. #18
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    I can't accept that puffing is ok.

    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

  19. #19
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    969
    i can hear where you are coming from, but perhaps what i am seeing isnt true puffing of the cell? if a cell was truly puffed, would it be hard and firm? have a look below at mine, it really feels like the expansion is just a pocket of air under the plastic that i can depress without any force

    https://www.youtube.com/watch?v=yCMuLg-qPHM

  20. #20
    RC Turnbuckle Jr. rag6's Avatar
    Join Date
    Mar 2008
    Location
    Accepting requests for bashing at GREENWOOD BASHPLEX in Pittsburgh PA!! Check the thread in the track buddy forum and reply there or pm
    Posts
    15,607
    Yes that is puffed. Not horribly, but it is puffed. It should not be squishy like that.

    I have used packs puffed like that in the past with no issues, but I would still be wary of it. Def keep it in a fireproof container or lipo sack.
    Sent from my moto e5 cruise using Tapatalk
    Last edited by rag6; 08-09-2020 at 12:30 PM.
    Ya can't polish fertilizer...

  21. #21
    RC Competitor
    Join Date
    May 2020
    Posts
    84
    Honestly, if your into this hobby lipo storage safety is a thing!
    A good ammo can and some cinder blocks make for a fine storage solution.

    Puffy is one thing... check the resistance! Higher resistance = more heat...

  22. #22
    RC Champion
    Join Date
    Feb 2020
    Location
    Canary Islands, Tenerife, Spain.
    Posts
    1,349
    Quote Originally Posted by varunaX View Post
    i can hear where you are coming from, but perhaps what i am seeing isnt true puffing of the cell? if a cell was truly puffed, would it be hard and firm? have a look below at mine, it really feels like the expansion is just a pocket of air under the plastic that i can depress without any force

    https://www.youtube.com/watch?v=yCMuLg-qPHM
    Looks very bad mate.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •