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  1. #1
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    Neg wire detached from battery pack

    Traxxas Series 5, 8.4V 5000MAH Power Pack. The solder connection for the negative wire came loose from the negative end of the battery pack. Have tried to re-solder this wire to the battery several times, but the solder will not stick to the battery metal. Talked to an "expert" at Radio Shack who said that most batteries have some sort of coating on the end which should be removed prior to soldering by sandpaper or filing. Tried that.... no banana. The battery metal seams to be solid, without a different coating on it, and it is hard like nickel. I'm not sure of the type of solder wire I am using and I have not tried flux paste. The solder will bond readily with the wire, it just won't bond to the battery metal. Hate to throw away an expensive power pack for what should be an easy problem to correct. ANY SUGGESTIONS?

  2. #2
    RC Turnbuckle Jr. Jimdog's Avatar
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    What wattage is your soldering iron?
    This will TOTALLY work, saw a guy on YouTube do it

  3. #3
    Marshal ksb51rl's Avatar
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    Before anything else, it is necessary to know why and how the negative lead become detached. If the cells became so hot that the lead unsoldered, you probably shouldn't bother.
    Alt-248 on the number pad =

  4. #4
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    Was advised by "expert" to use lower wattage iron. Used 30W on last attempt(s).

    Would the cells become that hot during operation??? That doesn't seem likely. Using Traxxas fully automatic aftermarket battery charger with protection, not the standard charger supplied with the vehicle. However, the batteries do get warm using this charger, but doesn't seam to be so hot as to cause solder failure.

    Will be hard to access the situation you have described if I can't re-solder the wire back on. Of course I am attempting to solder in a cold state as I was advised not to heat up battery directly. Must solve soldering issue to proceed further.

    More info:
    1. purchased 2 of these more powerful cells and the 2nd one has not failed in this manner.
    2. positive wire on the problem cell is still firmly attached.
    3. could the phrase "made in China" have any bearing on the failure?
    4. Regardless of cause, there must be a correct method to successfully re-attach and possibly continue using it.
    Last edited by Double G; 10-20-2015 at 07:20 AM. Reason: merge

  5. #5
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by 156Gheenoe View Post
    Would the cells become that hot during operation??? That doesn't seem likely. Using Traxxas fully automatic aftermarket battery charger with protection, not the standard charger supplied with the vehicle. However, the batteries do get warm using this charger, but doesn't seam to be so hot as to cause solder failure.

    Will be hard to access the situation you have described if I can't re-solder the wire back on. Of course I am attempting to solder in a cold state as I was advised not to heat up battery directly. Must solve soldering issue to proceed further.
    Yes the cells can become that hot during operation (not during a charge) but not without damage.

    Scuffing the end of the battery helps with solder adhesion, as does use of flux and (ohmygosh!) standard lead/tin solder.
    Wattage does not really matter since you are doing only one solder joint. Size of tip and therefore size of heatsink does matter. BITD, we used a hammerhead soldering tip (google it) for making end-to-end style packs. A lot of heat for a very short time is the safest way to go. If you have to apply heat for more than a couple seconds, you are starting to damage the cell.

    If you think the failure could have been a warranty claim, that would have been the best way to get the issue resolved.

    Quote Originally Posted by 156Gheenoe View Post
    More info:
    ...
    3. could the phrase "made in China" have any bearing on the failure?
    IDK - if you check the country of manufacture of just about every NiMH or LiPo pack you'll see on this or any other RC forum, they will read the same.
    Last edited by ksb51rl; 10-20-2015 at 06:37 AM.
    Alt-248 on the number pad =

  6. #6
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    Thanks for the much needed education on soldering.

    BTW, these power cells are about 3yrs old and have been cycled many times {ie, warranty?}. Is that a reasonable life expectancy for these devices before problems of any nature began to appear? My only hope is that re-attaching the wire will return this cell to a usable condition. At some point, most people will trash anything that doesn't function and the time/cost factor exceeds their tolerance. Guess I'm more determined than most but any issues post re-connection will exceed mine. Just ask my ex-wife!

  7. #7
    Marshal ksb51rl's Avatar
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    Neg wire detached from battery pack

    It seems warranty is not applicable and that you have gotten your money's worth. To have used the packs for three years and still be satisfied with their performance points toward greater than typical care, but they are a consumable with a finite life span.
    Do what you wish for the fun of it, but try not to fall into the trap of the fix costing more than it is worth. Best of luck to you.
    Alt-248 on the number pad =

  8. #8
    RC Turnbuckle Jr. Jimdog's Avatar
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    if the pack was still performing well i would still solder it. like ksb51rl said, use a lot of heat for a short time directly on the cell. if you dont think it is worth it i have a battery that came with my rustler that i only used a handful of times i would sell you. 3000 mah 8.4v about a year old.
    This will TOTALLY work, saw a guy on YouTube do it

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