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› Bad cell? 12s stick pack a complete loss?
10-25-2015 03:59 AM  25 months agoPost 1
Blackhawk6

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Livonia, Mi

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Hey everyone!

A couple months ago I had a crash that damaged this pack a bit. At the time it didn't seem like much to worry about as I couldn't smell any lithium from the puncture and all cells were balancing/charging just fine so I proceeded to Fly with it. Well, after about a month or so of flights, I noticed that that area of the pack was beginning to swell a little. Not the whole cell, just that area. Now, I've begun to monitor the pack during charging to keep an eye on the cells and IR's. Today I saw that the one cell was always charging up a lot faster than the others and the IR is more than triple from the other 5 in that pack.

Is this the sure sign that it's starting to go? I don't fly it "too" hard but some flights are harder than others... Based on what I've explained here and what the picture shows, would you call this pack DONE? I surely don't want this battery causing my $3k Goblin to come crashing down to the ground in flames!

I will not be buying stick packs for this reason any longer. I currently have 4 12s stick packs and although they're convenient, I'd hate for this to ever happen again. If I had 6s packs I could just replace that pack and move on. This situation causes me to lose the whole $350 12s pack

Anyhow, what do you guys think?

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10-25-2015 04:31 AM  25 months agoPost 2
Gregor99

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Western Wa

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Stick packs are usually two packs put together with heat shrink. Depending on the age of the packs it may be possible to purchase a new 6s pack, and replace the bad pack. If the pack has a lot of flights on it, combining the one remaining older pack with a new pack would work, but is not optimal and I probably wouldn't do it.

Revolectrix Beta Team

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10-25-2015 04:38 AM  25 months agoPost 3
Blackhawk6

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Livonia, Mi

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These are factory (Pulse12s 5000mah) stick packs, not two packs I put together to make a stick pack. With that said, I've never seen or heard of anyone tearing apart the two packs to replace one or the other. Have you? Can it be done? Can I tear the good 6s out of this?

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10-25-2015 04:43 AM  25 months agoPost 4
Heli Fanatix

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Fountain Valley, CA

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It can happen to a 6S or any pack. Normally a bad cell will not cause packs to burst into flame, it would cause ESC to voltage cut off mode (depending on how you program low voltage cut off).

Here's a thread we discuss on dealing with a bad cell.
https://rc.runryder.com/helicopter/t797880p1/

- Scott

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10-25-2015 06:16 PM  25 months agoPost 5
Gregor99

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Western Wa

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I think you will find that under the heat shrink of your 12s pack there are two 6s packs. I have assembled as well as dissembled this pack configuration several times.

During disassembly its important not puncture or damage the LiPo cells. I start at the end with small cut with scissors, taking care not to nick the cells. Then pull on the cut and tear it off around the pack.

Here is a Tech Tip from Chris Trebbi on the assembly section of the topic.

http://www.rchelination.com/diy-stick-packs/

Revolectrix Beta Team

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10-25-2015 09:50 PM  25 months agoPost 6
Blackhawk6

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Livonia, Mi

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That cell is definitely toast now. I charged it up and flew it today to see how it would handle and just as expected, it's a turd lol. As stated above, it did send me into soft cutoff. That one cell was almost 1/2 volt lower than the others after the flight. I guess I'll be experimenting with this and trying to tear it apart to save the good pack from the stick...

Thank you guys for the links as they're def good info for what I'll be doing. Stay tuned for the outcome...

Thanks!

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10-26-2015 05:32 PM  25 months agoPost 7
ticedoff8

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Morgan Hill, CA. USA

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As stated earlier:
The 12S "stick" pack is actually 2 6S packs in the same heat shrink.

The battery assembly house does this so they can sell more batteries.
If one cell dies, then the whole pack is toast.

I would steer clear of trying to salvage the "good" 6S pack.

It is kind of like working on your car's gas tank while you are smoking a cigarette.

It is really easy to short the mains and within a couple of seconds, you have a LiPo fire.

If you decide to proceed, I would discharge both packs down to about 10%, make sure you work outside (or place a couple of 12" square ceramic floor tiles on your work bench) and keep a bucket of sand close by.

Also, unless you are confident about your soldering skills, I would trash the packs.
Assuming you don't burn down the garage, the is a good chance your soldering job will let go mid-flight.
And there goes your $2000 Goblin

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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