I am assuming you want to build a 16s2p pack correct? You do want a 48 volt pack?
If so the Orion document gives you the exact same warning I did a few post ago, though I like there verbiage better then mine:
"Therefore, monitoring the voltage of either cell will show the same results (less the very negligible difference in voltage caused by voltage drop on the busbar). In the event that one of the cells develops a reduced capacity or high resistance (as is typical for aged or failed cells), the stronger cell will take more of the load and essentially prop up the weaker cell. In that event, the BMS is able to see a decrease in the overall capacity or an overall increase in resistance. With two cells paralleled together, a single weak cell can affect the resistance up to 50% and the capacity up to 50%. If three cells are paralleled, a single bad cell can affect the resistance and capacity of the total paralleled block up to 33% (with four cells paralleled, up to 25%, and so forth). As more cells are paralleled, a single failure becomes more difficult to detect, but redundancy is also increased since a single cell failure will have less of an impact on the overall performance of the battery. Cells directly paralleled with each other will automatically balance each other since they are permanently connected.
Note: While most lithium batteries can be directly paralleled together, check with the cell manufacturer to ensure that the cells can be safely paralleled and to see if there are any specific requirements for the specific cells used. In some cases (such as with some 18650 style cells), cell manufacturers may require individual fuses or fusible link wire to prevent over current through a single cell in the event of a cell failure or an internal short within a cell. Consult with the cell manufacturer to determine if such a design is necessary."
This is the warning from the "Standard Paralleled Cell Configuration" section, it is functional equivalent to my warning I already gave you. There is nothing "wrong" with a 16s2p pack, but a single bad cell can over time start killing its parallel partner. And the BMS can not easily detect this at first. As you already stated you don't have a choice on choosing this configuration do to battery box size issues. So get building.
But go in knowing the down sides. And take extra care to occasional test each parallel pair to make sure they don't have any large difference in resting and loaded voltage.
On Oct 2, 2018, at 5:43 PM, clh5_98@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
James,From what I read in the Orion white paper, the concern is about using parallel strings, not about paralleling cells in the same string. Everything quoted in the reply to my post about this white paper is about parallel strings, not paralleled cells in one string. From what I see paralleled cells in a single string are still just one string. I wonder how many paralleled cells are in CALB 180 cell? Just to be clear, I am not advocating, or entertaining the idea of paralleled strings. To do it correctly and safely would be cost prohibitive and would make for a complex system.John,In the Orion White Paper they talk directly about monitoring a group of paralleled cells as one cell. Check it out.Chris
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Posted by: "james@deny.org" <james@deny.org>
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