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Thread: nimh battery

  1. #1
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    nimh battery

    I bought a spare nimh battery from ebay it is the same as the one that comes stock with the stampede. I ran it today and when I opened my truck and went to take my battery out I saw that the plastic had torn open, and when I touched it I literally got burned(There is swelling). I think I may have ran the truck harder than normal. I was running on slick concrete and was doing donuts and full throttle for alot of it. I'm not sure if I want to charge the battery... I mean I know that its not a lipo but... Could the pack be defective or something? There was also a distinct smell coming from the pack which I am pretty sure is just from the plastic being really hot. Can a nimh pack be damaged from being discharged too quickly?

    Last edited by andale927; 03-30-2011 at 08:58 PM.

  2. #2
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    I wouldnt run it... its not likely defective... its jsut that in reality, the stock 7 cell pack is not up to the task of running this truck really hard. Did you have the high speed pinion in? Or the smaller pinion?
    Pede, Summit,
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  3. #3
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    It's just the stock pinion, I have a ***** ********* 3s 5000ma 30c pack coming in. I think I will just try to get the seller to take it as a return.

  4. #4
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    oh wow, this is the response I got, pretttyy cold:
    Hi,

    We cannot warranty any Traxxas items. Traxxas policy is that the end user must deal directly with them.

    Also, I am sorry to say, but our return policy does not include electrical items. This is clearly outlined in all of listings under Returns/Refunds.

    For what it's worth, I run the 8.4V / 3000 packs everyday in several vehicles. They get so hot the shrink wrap melts, the labels peel off and they will certainly burn you if you grab it right after a run. That is the nature of Ni-Mh batts.

  5. #5
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    So it most likely won't be dangerous if I run it again?

  6. #6
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    Try charging it and see what's happens. Just watch it like a hawk. When I charge my batteries I either put them in a lipo bag or a small stone ash try-ish thing as a precaution. I run my pede pretty hard on the track and have never had this happen so far. Good luck!
    -Slash 4x4 MT 2000kv
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  7. #7
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Man, I would NOT run a battery thats got so hot the actually individual cell shrink has melted off... thats NOT a good sign. Try it if you want to risk it but id be cutting my losses and throwing that thing out... or try a charge back through paypal... or just call traxxas and see what they say... go to the source and get professional advice. If it were ME... id never run that pack again.
    Pede, Summit,
    ERBE, Rally,
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  8. #8
    Marshal Dadx2mj's Avatar
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    I have to agree with Pavmentsurfer on this one. When a nimh pack gets hot enough to melt the shrink wrap it has most likely done some damage to that cell. You might get another run or two or maybe more out of it if you are lucky but the odds are the issues will only get worse and more damage will be done to the cell. IMO it is not worth the risk of the celll venting during charging and damaging something or when you are running it and damaging your truck and or the electronics.
    BlindMan Racing
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  9. #9
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    yea to some it up, more than likely that cell had some internal resistance built up, or the individual voltage of that cell was lower than the others, and then it couldn't handle the extra amp draw which caused it to heat up. i doubt that its something you did, the cell was probably weak from the get go. Nimh's are great packs and high quality cells if cared for properly can take some real abuse. But i would not run that battery ever again. maybe take that one cell out and make it a 6 cell pack. But certainly not run it as is. My advise call traxxas and ask for help explain the situation and hopefully they can help. also look to paypal and see if them or ebay can do any thing for you. someone owes you for the defective cell.
    Man i need more than 50 characters.

  10. #10
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    okay thanks guys i tested the pack voltage and it is at 4.3 volts! my other pack is 7.5 when fully discharged. i will contact traxxas first and if they don't agree i will do a charge back through paypal.

  11. #11
    RC Turnbuckle Jr.
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    I test and sell RC batteries for a living and I want to make sure it is understood that what pavmentsurfer wrote regarding the pack in question is 100% correct. If the pack got hot enough to melt shrink off it, DO NOT attempt to charge or run it again. Doing so could cause serious personal injury or property damage!

    When you were running the pack as noted above, did you run the pack hard until the truck slowed or stopped or something else?

  12. #12
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    I agree with not charging it ever again... call traxxas and see what they say. I cant imagine that they would sour a customer over a $25 item. IMO they most likely will replace it for you.

  13. #13
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    Yes Traxxas should replace it for you. But just a warning, its usually not a good idea to buy products that can be defective off of ebay because a lot of times the smaller people will not back you up when something goes wrong, or give you a refund. If I buy stuff of of ebay like batteries and electronics I be sure there is a warranty, or the seller has at least 99.8% positive feedback. If it is bellow that it seems to be they will not always go outside their warranties and policies to do the right thing by looking at feedback.
    So I taped my hamster to the Pede..

  14. #14
    Marshal Dadx2mj's Avatar
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    Knowing Traxxas's track record for customer service it would not surprise me if they did help you out but I think it is asking a lot to think they should offer any warranty coverage on a pack you bought presumably used off of ebay. There is really no way to know how old the pack is or how many cycles it actually has on it.
    BlindMan Racing
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  15. #15
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    having it at 4.3volts is really bad.a nimh discharged to less than 0.9volt per cell is borderline.A good brand might be ok a cheap brand won`t be at 0.9v per cell.1.1volt per cell discharged is good. I think two cells have reversed polarity due to bad charging.having one at 7.5v i wouldn`t charge it higher than the correct rating.charging higher is what you do to give it an extra boost once in a while for a race.

  16. #16
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    Is there an update on this situation? Call Traxxas? Replaced? Stuck with it?
    Tomorrow can wait till tomorrow.

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