Rebuilding a 3S LiPO pack.....single new cell??

[Charlie-III]

OK, I didn't see a similar thread, so here it goes.

It appears we have a "mid life" 3S LiPO pack with a puffed cell (crash damaged). If I can get a similar cell, has anyone just replaced a single cell to repair a 3S (or even some other qty of LiPO cells)?

I understand the discharge rates may be different (new cell vs old cells), but this is a practice pack, not a comp pack.

I believe the pack is a 1600mah. Not a great pack, but a practice pack non the less.

Thoughts?

[freakofnature]

id talk to chris on that 1 charlie he the expert on them

[Charlie-III]

Hi Mike....I have bits for you.

I will see what others have to say before I bother Chris (unless he pops in).

[forbid89]

I'm no expert but I would say that unless you can closely match the characteristics of the good cells then I would either dispose of it or make it into a 2S. Especially since you said it's a practice pack and it's relatively low capacity it seems like more trouble than it's worth unless you just want the experience.

[Chris_The_Battery_Man]

Honestly,

You will be wasting your time. Unless you manage to find the same cells, then the pack will always be out of balance. Not to mention, the way the Chinese assemble the packs, doesn't allow you to safely dis assemble them. They have double sided tape between the cells. And when you try to peel them apart, it separates the lining of the cells from the innards. Thus creating an air pocket, and making the cells inflate.



Don't risk messing with it. I wont even dis assemble Chinese made packs. Just replace it.

[Charlie-III]

Chris,

Thanks for the info. I sorta figured it was a waste of time/effort, but wanted to ask.
I'm still sorta new to LiPO's, my old Nicads or NiMH's I would have fixed in a heartbeat........

[Pointman]

Get something like this. You won't be disappointed!

http://cheapbatterypacks.com/?apage=...uid=C1AE3BG841

[Charlie-III]

Originally Posted by jrmyfair

Get something like this. You won't be disappointed!

http://cheapbatterypacks.com/?apage=...uid=C1AE3BG841

We just received qty-3 CBP Elite 3S 1300's on Monday. They go with the 2 I already had.

The pack I'm asking about is for fun runs.

[Trubble]

Sorry for the thread hijack, but here goes.

I'm extremely new to LiPo, but not so much to RC.
Got a new LiPo the other day from the Scratch & Dent bin at an online retailer (as is- no warranty, no returns). The cells are fine, not the least bit puffed, still nice and firm. Charger fails to recognize the pack. VOM shows absolutely zero volts at the connector. Thus, I suspect a solder/connection problem.
I've got a new pack ordered, but would like to try my hand at getting this one back. Any idea what I should look for under the wrap and tape? Is this something I can fix, or am I looking at special supplies/procedures for soldering the tabs? All my experience in this has been in rebuilding NiMh packs, just never tried to take on LiPo yet. I'm confident in my abilities, as I've been soldering for 20+ years, but it's all been wiring, circuit boards, and (NiMh/NiCad) battery terminals, never tried soldering aluminum. (If the tabs are even aluminum, don't know yet, haven't opened up the pack.)
Any tips from experienced LiPo builders would be appreciated.

[forbid89]

Sounds like you have all the tools you need to diagnose and probably fix the problem (if it is a broken connection). Look at the pictures here and you can get an idea of how the packs are constructed:

http://www.dream-models.com/eco/LipoPack.html

Use your multimeter to track down the broken connection and solder it back up. Just use caution not to overheat the tabs and not to puncture the cells in any way.

[Trubble]

Pretty much exactly what I was looking for.

Thank you very much.



Edit: After gently scoring and tearing the factory shrink wrap off, and peeling the tape, got to the top of the battery. Checked the tabs on one cell, voltage, checked the other side, voltage, checked the pack's tabs, voltage, checked the connector, voltage. Not sure what that small circuit board on top is (internal LVC?). Electrical taped it back up, tossed it in a sack, and ran it through the 230, and now it works fine.