battery packs

[Sovran]

I finally got my battery packs to disassemble and make my dna20 mod. Desoldering wasn't an issue at all. The cells are stuck together with double sided tape and when separating them a couple issues arose. 1st, the outer covering tore on one cell. It was intact under the covering but there was a definite solvent smell. I am afraid I have damaged this cell. Is there any way to tell for sure? What would be a better way to separate the cells from the tape? 2nd, the cells are soft, almost like clay in a bag. They flexed a bit during separation is this an issue? At this time all cells read between 3.8-3.9 volts.

45 mins later there is no longer a solvent smell from the cell with the torn outer cover. It still reads the same voltage. I had it sitting outside in case of fire.

 

[jmlott]

Paging Bapgood!

Seriously though, I'm really interested in knowing about this as well. I've been too chicken to pull apart battery packs, so the more info I can find, the more comfortable I will be. Bapgood should be around sometime soon and I'm sure he will have the answers.

 

[Java_Az]

I finally got my battery packs to disassemble and make my dna20 mod. Desoldering wasn't an issue at all. The cells are stuck together with double sided tape and when separating them a couple issues arose. 1st, the outer covering tore on one cell. It was intact under the covering but there was a definite solvent smell. I am afraid I have damaged this cell. Is there any way to tell for sure? What would be a better way to separate the cells from the tape? 2nd, the cells are soft, almost like clay in a bag. They flexed a bit during separation is this an issue? At this time all cells read between 3.8-3.9 volts.

Sounds like they are soft cells. In that case, if it is ripped open then it should not be used.

best way to get tape off things is to heat it up then it peels away very easily. But this might not be a good idea with batteries since you can damage them if excess heat is used or even make them vent or blow up.

battery packs usually have a protection circuit in them. by taking the batteries out of the pack without the circuit these are unprotected batteries. I suggest you got you some protected batteries for your mods , better safe then sorry

 

[Sovran]

@java the cells will have PTC fuses in line. The DNA20 board has protections as does the DNA charger.

 

[bapgood]

Do you have pics of the cell? Also what brand were the batteries?

I have never seen a cell tear that didn't start on fire. Usually when a cell is opened to air a chemical reaction happens....ie fire.

 

[bapgood]

well at least the down time gave me some time to compose.

I have never seen an rc type lipo with any kind of protection. some have pcbs for soldering tabs together, but no other components for a protection circuit.

Some packs have a thin piece of plastic wrapped around the cells. here is a pic of one I recently did. If this is what ripped you should be ok.

If the aluminum shell of the cell is actually ripped I would find a nice place outside away from things to put it. A fire pit and something long with a sharp point is a good way to end the life of lipo, because you don't want to just throw it the garbage and have it start on fire.

Separating the cells can be a huge pita sometimes. I have never used anything to help, I usually just go slow and work around the edges and keep working it slow until they come apart. Heat to a point shouldn't hurt and is worth a try. Hardcore rc racers actually use battery heaters to heat the pack right before use and while they charge, but im not hardcore and not sure what is to hot. Something else I have thought of trying but haven't is acetone (fingernail polish remover) it should soften up the adhesive.

As far as a cell being soft, that is kind of relative to interpretation...but in general they should be relatively firm. A lipo that has been overdrawn of current will balloon but will usually be tight. Sometimes separating the cells will slightly pull the cell apart and feel like there is air inside, I have also received brand new packs that felt that way...usually cheaper brands. I have had packs that were smashed in a crash and looked like crap and worked great for a long time, I have also seen packs go up in flames that looked fine....All it takes is the right puncture.

If you are going to mess with lipos, just be safe...a large concrete floor or similar is your friend if things get ugly....a lipo sack/sink/tub/pot/pan/etc will do if your indoors and can get a problem cell/pack into it. I have never seen a cell/pack explode but if it was contained when it combusted im sure it could.

 

[Sovran]

Thanks Bapgood. I will get a pic of it this evening after work. I just looked outside on the porch and no scorched concrete. I put it in a plastic bag to help keep any moisture from it. It is a cheap Chinese pack from the place that cannot be mentioned. The price and size were right so I figured I would give them a try. My next purchase will be a lipo bag. I will try a blow dryer on the second pack and see if that helps separation.

 

[bapgood]

Thanks Bapgood. I will get a pic of it this evening after work. I just looked outside on the porch and no scorched concrete. I put it in a plastic bag to help keep any moisture from it. It is a cheap Chinese pack from the place that cannot be mentioned. The price and size were right so I figured I would give them a try. My next purchase will be a lipo bag. I will try a blow dryer on the second pack and see if that helps separation.

Hopefully if your pack is ok from the tear it will be ok from the cold, if it is cold where you are. You never want to charge a cold lipo (probably any lithium battery). Let it warm up to room temperature and check the voltage before charging or using, trying to charge a lipo that has to low of voltage is dangerous. Most rc type lipo chargers wont charge if the voltage is to low, but Im not sure about other chargers like the DNA charger. Lipo's do not like cold temps and cold temps for an extended period of time can kill a lipo.

It may be easier not to try to separate the cells, especially for a vaping application that doesn't really have high current draw. You could unsolder the cells and keep them stuck together and just run some good wire across the cells to the + and - tabs, 20g should be fine (the same as you us to run to the dna20).

If you do try to separate the cells, using a hair dryer should be fine. I looked up a lipo heating box and it heated up to 50c/122f

 

[Sovran]

I didnt think about the cold. It stayed above 40 last night and I wasnt planning on using it cold. Pure fire prevention was the thought.

Here is the pic.

As for using the pack and changing the config, I cant. Maxi will only hold 2 cells and it was a 3s pack. I will bring home my IR thermometer to monitor the temp of the pack while using the hair dryer.

 

[bapgood]

Here is the pic. View attachment 177847

That is new to me...that must be the inside liner to the aluminum cover. I would cut your losses and ditch that cell.

Mamu did a great post on separating lipo cells....http://www.e-cigarette-forum.com/forum/battery-mods/379806-delsy-dna20d-2.html#post8624319