End soldered cells, disassembly?

Best shot: cut them apart first, then use a serious iron, cleaned and well tinned, to quickly pop the remaining tabs off the poles.

If you have to hold the iron to the pole longer than a couple of seconds, you ain't doing it right, and what you'll end up with are flashlight batteries...

/daytripper

Thank you for the suggestion, daytripper. The cells I bought are tabless NiMH Sanyo 3000 mAh, and I had them soldered together with a special soldering iron (hammer head tip). The poles of each cell were tinned then pushed together. They are very closely mated, making it very difficult to get any cutting instrument between them. Do you think a razor blade may work?

Best scenario, sell them as is to someone who needs them. Then we'd both benefit. But the delivery and collection of $ may be of concern. Know anyone interested?

Wan

If they were soldered properly, then any attempt to separate the cells will ruin the 2 cells where the separation is attempted! Usually what happens is a hole gets ripped in the bottom of the cell if prying. If heating, then the cells get so hot they vent the over-pressure.

So basically, use as is or sell to someone who can use the stick.

David

I have assembled end-soldered packs. I have had pretty good luck by slightly flexing the joint between the cells. This will fatigue an ordinary tin-lead (63/37) solder, and the joint will fall apart.

I don't know how badly this damages the cells, but they looked fine. I used them in another pack without problems. However, the cells were smaller than yours - Sanyo 500 mAH.

Your mileage may vary.

-- Mike Norton.

Drain the cells completely, and keep them drained for a while using a short. Then, using a very thin bladed knife, insert it between the cells, and roll the cells over the work bench keeping slight pressure on the knife. That way you may cut the solder without cell damage.

Mike, Sounds like it could work but I have the electrical solder. I don't know it's composition of tin and lead.

Still, I should try it on cheap alkaline C cells first before I ruin NiMH cells. Also as you know my 3000 mAH sub C cells are of greater diameter and may require more leverage to flex?

Wan

If it is Radio Shack electrical solder, it is close to what I used.

My cells were NiCd, not NiMH. In either case, I don't think alkaline cells are a good mechanical substitute for deciding whether the process works for you.

I liked the poster that recommended using a thin blade, using it to roll the cells back and forth. I would bet that this fatigues the solder.

Pé, I finally see what you look like when I clicked onto your web site. The photo is of you, is it not?

I appreciate your idea of rolling a thin blade between the cells. This may be done without undue stress to the negative pole, the bottom of the cell. I will try your method on cheap end-soldered cells before attempting on the NiMH packs. 3 out 4 times leaves me about 30 out 40, in turn leaving me about 5 packs of 6 in series.

I could drain the whole battery pack by connecting a 12 V automobile lamp. Or must I drain each cell?

Another question is, will draining the cells completely damage the NiMH cells as it does to Li Poly cells?

Thanks, Wan

NiMH is no different, and may be drained completely. Dont do that with LiPo though, unless clad in armour, and in the open :-) A lamp over the pack is good enough. If one cell is severely different and runs the risk of reverse charging, the pack was no good anyway, and not worth saving but cel by cell. The last bit can be accomplished by twisting the cells, and the join will fal apart. The draining is required to reduce the high short current that may occur.

Yes, that me, though my hair grows white quite fast now. So much to do, and so little time.

Put the pack in the freezer, after it's really cold a sharp rap on a the edge of the workbench will snap the batteries appart. Just try it, it works.

It sounds so simple. Hmm... I ought to give it a try. As it is, the batteries will just be wasted since I've gone Li poly.

Yeah, Pé. So many things to do and so little time. Can you invent a time machine? Off topic. Well, what the heck, enjoy! But thanks for your suggestions.