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Thread: Charging LIPOs

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    Charging LIPOs

    Went and bought two 11.1V 5000 maH Traxxas brand batteries and threw them on the charger put the second when on and then had to leave so i turned it off when i got back i turned it on and it would only charge at like .1-.4? I don't quite understand what that's all about did I do something wrong or what?

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    When you balance them there off that I assume?
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    RC Turnbuckle Jr. mike-susieq1's Avatar
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    you didnt leave it connected still when you left right? if you did then the pack might have gotton damaged or its full. disconnect it from the charger and turn the charger off unplug it for 1min then plug it back in and turn charger back on then connect lipo to it and select balance charge at 5.0amps/1C charge rate. what is the cell voltage per cell? also what is total voltage for pack? what charger are you using?
    DEU 8:18 ESV

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    Quote Originally Posted by chadkillzone View Post
    When you balance them there off that I assume?
    Not sure what you mean sorry

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    Quote Originally Posted by mike-susieq1 View Post
    you didnt leave it connected still when you left right? if you did then the pack might have gotton damaged or its full. disconnect it from the charger and turn the charger off unplug it for 1min then plug it back in and turn charger back on then connect lipo to it and select balance charge at 5.0amps/1C charge rate. what is the cell voltage per cell? also what is total voltage for pack? what charger are you using?
    They were not charging when I left. The batteries I'm using are the traxxas 25c 11.1v 5000MAH LIPO on a traxxas ez charge plus

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    RC Turnbuckle Jr. mike-susieq1's Avatar
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    then perform what i mentioned and see what the result is. check voltage per cell and total voltage per pack. per cell needs to be atleast above 3.0v per cell no lower for it to still be a good pack and 9.00v pack minimum. reset your charger by unplugging it for a little while and adjust charge rate if needed see if that works. not too familar with the trx plus charger.
    DEU 8:18 ESV

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    Quote Originally Posted by mike-susieq1 View Post
    then perform what i mentioned and see what the result is. check voltage per cell and total voltage per pack. per cell needs to be atleast above 3.0v per cell no lower for it to still be a good pack and 9.00v pack minimum. reset your charger by unplugging it for a little while and adjust charge rate if needed see if that works. not too familar with the trx plus charger.
    Well reset it and plugged them in the first one each cell was around the 4.0 mark and the second one is at4.0 for two of the cells and 3.97 for the other one so of that 3.97 is acceptable I think we r ok?

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    On a side note this one one lipos has been charging for 89 min to me that seems to be a bit
    Last edited by MTXThunder9500; 05-20-2012 at 04:51 PM.

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    What charge rate are you using? 0.2A? If so, you can bump it quite a bit higher. The final full voltage will be around 12.6v.
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    Quote Originally Posted by Double G View Post
    What charge rate are you using? 0.2A? If so, you can bump it quite a bit higher. The final full voltage will be around 12.6v.
    I started with 5 amps and it dropped off to this after a while. I called the store and they said that it will do that cause its balancing the cells? Don't quite understand why it would drop off to virtually nothing?

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    It drops down to a lower current because as the packs voltage goes up and it's reaching maximum capacity its resistance goes up.

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    Quote Originally Posted by Freeagnt54 View Post
    It drops down to a lower current because as the packs voltage goes up and it's reaching maximum capacity its resistance goes up.
    Ya for it to drop down thats normal. I got worried to when i first saw that. 5000mah battery you can charge at 5 amps. Was it almost done once you took this pic?
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    Quote Originally Posted by minirevobasher View Post
    Ya for it to drop down thats normal. I got worried to when i first saw that. 5000mah battery you can charge at 5 amps. Was it almost done once you took this pic?
    Nope it wasn't almost done. The battery acutally crapped since then. Now have replaced it.

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    on the pic it switches from constant current to constant voltage when nearly full to balance the cells off. I am wondering why it's been running 90min and only put 513mA into the battery.Unless the cells was way out for some reason.
    Problems.The manual's good starting point. Simple

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    Quote Originally Posted by trax de max View Post
    on the pic it switches from constant current to constant voltage when nearly full to balance the cells off. I am wondering why it's been running 90min and only put 513mA into the battery.Unless the cells was way out for some reason.
    Ya thats what i think. He said the battery took a huge crap after this pic was taken
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    RC Turnbuckle Jr. mike-susieq1's Avatar
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    i see some lipo chargers do that take a long time to charge sometimes and sometimes its fast that way its suppose to be. unless its a high end charger like those out that that cost like over 90 then it usually doesnt do that unless your pack is off balance then it will take a little longer to balance charge it. it might have been that your lipo was going out also thats why it didnt take a full charge.
    DEU 8:18 ESV

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    Quote Originally Posted by MTXThunder9500 View Post
    I started with 5 amps and it dropped off to this after a while. I called the store and they said that it will do that cause its balancing the cells? Either you misunderstood or (at least as likely) they did not explain it correctly or themselves have no idea why this happens.) Don't quite understand why it would drop off to virtually nothing? See last sentence in last quote.
    Quote Originally Posted by Freeagnt54 View Post
    It drops down to a lower current because as the packs voltage goes up and it's reaching maximum capacity its resistance goes up.
    Nope. This has nothing to do with it.
    LiPo Charging: LiPo batteries generally require a constant current, constant voltage (CCCV) type of charging algorithm. In other words, a LiPo battery should be charged at a set current level [we use 1C to 5C, depending on the pack instructions] until it reaches its final voltage. At this point, the charger circuitry should switch over to constant voltage mode, and provide the current necessary to hold the battery at this final voltage (typically 4.2 V per cell). [As capacity draw closer to 100% less current is needed to hold the cells at 4.2 V per cell.]
    I hope this explains better why current drops off at the end of the LiPo charge cycle.
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    Quote Originally Posted by ksb51rl View Post
    I hope this explains better why current drops off at the end of the LiPo charge cycle.
    So then it is normal for it to drop off like that then if i'm reading that correctly?

  19. #19
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    Yes, it has to drop off. If it did not, the cells would overcharge.
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    Ok thanks!! So having said that is there an average time that it should take to charge a traxxas 5000mah 11.1v battery?

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    RC Turnbuckle Jr. mike-susieq1's Avatar
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    normally 1 hr at 5amps i've been told but can vary a little depending on which charger your using like quality wise i mean imo atleast. some chargers balance lipos better than others.
    DEU 8:18 ESV

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