I have two zippy 6s packs that each have one damaged cell in them, so I need to find a way to remove these from the packs. All the cells are stuck together with some kind of glue (I have no idea what kind), and so just pulling them appart isn't an option.
I was thinking of finding some kind of solvent that wouldn't also damage the Lipo pouch plastic at the same time - Any suggestions or other ideas?
I never used anything to dissolve the adhesive on my Turnigy Lipo 5AH packs... when I had bad cells I would just desolder with wick one cell at a time and use a teflon type spatula to work between the cell pouches and seperate their adhesive. I've used this method on dozens of 5 and 6S packs to rip them down to bad cell points and rebuild or to collect the cells from smaller packs and I've never caused cell damage this way...
I don't force anything, I use a gentle rocking motion and I don't hold the cell I'm removing... I hold the rest of the pack which remains.
I would be afraid of any type of solvent use especially in a pack where cells may have ruptured, bloated, etc... or a physical break in a pouch may exist - that's me though, someone may have better ideas!
-Mike
PS: A hair dryer on medium heat will make the job go faster because it will weaken the bond of the adhesive (or atleast it does for Turnigy Lipo packs).
Thanks for your input, Mike, I'll try using a thin teflon sheet I have and some extra heat to see it that helps. They are zippy flightmax packs, not turnigys so we'll see if they use the same glue type.
If this doesn't work well and no one suggests any potential solvents to use, I guess I'll be doing some "solvent resistance tests" on the Lipo cell's pouch plastic.
If this doesn't work well and no one suggests any potential solvents to use, I guess I'll be doing some "solvent resistance tests" on the Lipo cell's pouch plastic.
I hear ya, my guess is they are all very similar (the adhesive needs to expand with the cell pouches or it would tear them open) in physicial construction since I think the chemistry and physical charactoristics are identical for almost all pouch type cells.
If your going to do "solvent resistance testing" - just one favor, do it outside and on concrete or in sand (make some glass).
Well I tried Mike's heating idea to seperate the cells in the first of my 2 Lipo packs, and it did work, but I didn't find it to be an ideal solution.
So I did end up doing the solvent test on the first dead Lipo cell I had removed using heat. I figured I'd start with something that usually doesn't bug plastics too much - some type of alcohol. I checked and had a bottle of Methyl alcohol handy so I tried this... and succesfully removed the residual glue from the dead Lipo pouch! And no signs of any ill effects on the plastic pouch even after a couple minutes of leaving the alcohol on it.
So for the second Lipo cell to be removed I used a brand new exacto blade (medium size) and dribbled methyl alcohol down between the cells to be seperated. The blade slides slowly down between the cells as the glue lets go, and it makes it very easy!
Now since the dead cell in each pack was in the middle, I proceeded to break the green board with the soldered lipo tabs into two parts, each containing the good cells and still connected together in two seperate groups now. Then I just flip around both groups that I just split appart and tape them back together so the cells end up in the right order again to make a new 5s pack. Et voilà!!
So Methyl alcohol works great, but maybe ethyl alcohol and/or isopropyl alcohol might work too since they have similar solvent proporties.
If it's hot-melt glue, I've found that even isopropyl alcohol works well to make the glue let go. It doesn't dissolve the glue, but it weakens the bond and makes it easier to mechanically separate.
Why is it always the middle ones that die, why can't it be the ones on one end so you only have to seperate one lot of cells!?
I too have had a few go and found methyl alcohol to be ok but this other solvent i use at work called unisolv is even better. This stuff instantly removes the residue left behind from tape, stickers etc and makes removing lipo glue easier. The main ingredients are dipropylene glycol methyl ether and benzyl alcohol, so if you've got any of that sorta stuff laying around try that
Using a blade to seperate foil pouches is a keen move! The first time I did one I was super slow and cautious and it was like diffusing a bomb, but after seeing Lukes videos I don't think I'd be so scared if I did happen to puncture one. Sure you've gotta be ready to chuck it out the door into a clay pot or something but its unlikely they'll just go up in your face.
So for the second Lipo cell to be removed I used a brand new exacto blade (medium size) and dribbled methyl alcohol down between the cells to be seperated. The blade slides slowly down between the cells as the glue lets go, and it makes it very easy!
Thanks Zap Pat!
