Greetings - some of you may have seen my post in the A123 thread or the battery builders thread, but I purchased two sets of 80 A123 cells from Battery Clearing House just recently. Surprisingly it took only 4 days from order date to receipt of the packages!
I got them today:
One of these sets is for @Technovore but the other one is for me. Might make a few packs for different people once I receive my wider 12mm nickel.
Anyway, the glaringly obvious realization after buying them is that they are obviously not raw cells. These require some amount of disassembly. The following is how I have figured out how to disassemble them in about 10 minutes each.
My first try took about 25 minutes to disassemble the pack, which is quite a while if you think about it. 25 minutes for 8 cells, and there being 80 cells, or 10 packs… Well, it adds up.
The following timelapse shows the first pack that I disassembled, I unscrewed the enclosure, broke apart the cells by just breaking the pcb, and then pried off the ends on one side of each cell and proceeded to slowly rip off the nickel. This proved to not be as timely as I wanted.
My second method worked pretty well, but it was still a bit slow since it was my first time doing the method. You can see that I pulled out the Dremel to cut the nickel strips but I ended up not needing to do this later. This method only took me 11 minutes to completely disassemble and get to the bare cells.
Finally, my third method is the one I will continue using and is what I describe below. This method / improved method 2 took only 9 minutes.
How To:
First, remove the five torx screws from the bottom of the battery tray. They are very obvious, and there are no hidden screws or screws covered by stickers.
Next, take off the bottom piece of plastic and then tilt the battery pcb assembly out and pull to slide it out of the top cover.
I’d recommend putting on safety glasses and gloves for the next step to protect your eyes from fiberglass and you hands from the pcb components and sharp edges. Essentially, you want to break each set of two cells apart from each other. Start with the middle one and snap it in half. There might be a tiny bit of sparking but if you do it quickly and are careful, there shouldn’t be any issues. I wouldn’t let the cell contacts touch each other but you can break it pretty easily.
Next, snap each of the other two sets apart from each other.
Finally, snap the last two apart from the inverter transformers at the end. The heatsink will probably just fall off when you break it apart.
The next part is a bit more difficult and takes some more precise maneuvers. Start by picking one of the sets of cells. Essentially what you want to do is break the nickel off of the battery pcb at one end of the two batteries.
You can see that right where the board broke, the end of the nickel can easily be grabbed with pliers and peeled off the board. Don’t peel the nickel off the battery terminal yet. See below:
After peeling the strips out of the battery pcb, you can lift each cell up individually to pull it off the other side. This is where caution needs to be used. On A123 cells, the large flat side (positive, they’re opposite of 18650’s) is VEERY thin. You must be extremely careful because if you pull off the nickel incorrectly, it will tear through the metal and put a pinhole into the cell. Because A123 cells are so safe, nothing will happen, but it isn’t recommended to use a cell if you put a pinhole in the positive terminal.
On the smaller side with the center terminal, you don’t need to be as careful because the metal is thicker. On the smaller side, you can usually use the pcb to rip the nickel off the end of the cell, however, if the nickel breaks off the board, no worries because it is easy to remove later.
On the larger flat side, you MUST use a twisting motion to create horizontal shear forces in the nickel spot weld. By using this method and twisting slowly, you can break off the nickel attachment without puncturing the cell. If you pull away from the cell, causing tension in the metal, it will likely rip through. Out of the 32 cells I’ve taken out so far, I accidentally tore 4 of them. The first two were in the first pack as I was learning, the others were because I tried to do it too quickly.
Repeat this same process with the other three sets of two cells. At this point, you’ll have a bunch of free cells, some of which will still have nickel on the ends. These are the ends that you pulled off the pcb earlier. It turns out that this part is actually easier. Using a set of normal pliers, the rest of the nickel can pretty easily be removed.
For the large side, again, you want to use a twisting motion to remove the nickel. Grip the strip as close to the cell as possible, and slowly twist it left and right, with the axis of the cell. You should be able to pop off all four of the connections.
On the smaller end, grip extremely close to the cell on the nickel. Now, holding firmly, use the cell top as a lever to rip the nickel off. In the picture, imagine the pliers traveling to the left and down. It is pretty simple once you do it a few times. After you break off the first two spot welds, re-grip close to the metal again and lever the last two off. The motion is kind of like a roll-peel action.
And there you go! You’ve now harvested cells from an EMC pack. Now just repeat it for the other 10 packs in your box.