I found another power pack in the recycle bin. In case no one has noticed, I have been posting the strange, rare finds to this thread. I would welcome anyone else also posting their unusual finds also.
Anyway, once again this pack looks brand new. However I suspect that it was to be installed inside of some piece of equipment. If that was the case, it could have been heavily used, but show no physical signs of wear and tear.
There it is. “36V/4.4Ah/158Wh”
There are warnings right on the label, first warning is “do not disassemble or open”
Warnings aside, I did press on, very carefully. This is dangerous stuff, should not be done by anyone not knowing what they are doing. (I don’t either. But I am really, really careful )
So I took the first 2 layers of shrink wrap tubing off. The tubing was at right angles to each other. At this point I can see that this pack contains 20 - 18650 cells in a 10S2P configuration. Also at this point I am guessing that these cells will turn out to be of ICR type and not IMR. Two 18650’s in parallel would give the 4.4Ah capacity stated on the label if each cell was rated at 2200mAh. Already this pack is a little less interesting to me.
There is only a 2 wire socket that plugs this pack into the unit. All charging and discharging is done through those 2 wires. After removing the shrink wrap, a circuit board is now partially exposed. Also I can see that the cells are purple. I like the color!
There were 2 layers of paper tape also wrapped around the pack, each once again at right angles to each other. Here it is with 1 of the layers of paper tape removed.
Now we can fully see the heatsink for any power FET’s that may be in the circuit. Also we can now see the sense wires going to each of the cells.
Here it is after taking the second layer of paper tape off. After noticing the wimpy weld joints on the tabs, I am now pretty confident that this is not a high amp pack.
As I mentioned, the weld joints are pretty wimpy. Here are the welds of this pack on the right and the weld joints of a drill pack on the left. A drill pack, with type IMR cells, are built for much higher current loads.
Recently there was a group buy on the forum here for some Samsung 30Q’s As IMR’s are manufactured for high current loads, the come with flat tops on the postive side. The intention being that they will be welded into a pack. Some of the members here opted to have a third party install button tops. I hope those button tops were welded with the same kind of weld as a drill pack. Worse yet, I hope the button tops were not merely placed on top and held in place with another layer of shrink wrap.
I have seen that done with some rewraps of cheap UltraFires where the original cell was a flat top.
Anyway, I didn’t even think to measure the voltage of the pack. Voltage across all 10S2P is 36.0V!
To me that is a VERY, VERY good number! It is possible that this is a brand new pack, having never been used. 36.0V is just what I would expect to see if it was. Had it been any other number, it would have meant that this pack was used. And if it was used, it’s condition could range from very good to very bad. Before I tear this pack down any further I want to test the cells to see what condition they are in. I also want to see if this pack will balance charge with just an input charging voltage. Most drill pack chargers that I see connect to a drill pack battery with 3 or 4 or more connections. Even when the BMS circuit is in the pack.
36.0V divided by 10 cells in series equals 3.60V per cell, and that’s what each pair are!
Does anybody recognize what these cells are? I am thinking they are 2200mAh, ICR’s
EDIT: According to the label outside the pack these individual cells shoule be 2200mAh each, however dividing 7.2Wh by 3.6V as per the cell wrapper, we get 2000mAh cells.