I would choose a BMS first and then select a number of cells in series that fit the Charger and BMS voltage.
I don't know that choosing the number of cells arbitrarily as you are (29s) is a good idea when trying to design the entire system. For instance: If you choose a BMS that has a limit of 24 cells, you won't be able to use 29s. If you get a BMS that can do 32 cells, then you're wasting 3 channels. Same with the voltage on the charger.
If you are using the DeltaQ, for instance, and I program it for you, then these are the voltages available:
Algorithm ID | 96V model cutoff |
* 67 | 98.4 |
128 | 109.44 |
211 | 110.88 |
163 | 114 |
53 | 116.784 |
123 | 119.76 |
164 | 121.584 |
135 | 124.512 |
177 | 131.376 |
With 29s (which is a weird odd number to begin with), you'd be limited to algorithm 67 and would only charge to 98.4V, as the others would overcharge the A123 cells. If you chose 30s, you could use algorithm 128, and charge to 109.44V (3.648V per cell, which is great). So I would choose the number in series based on your available equipment. I think the 1231C goes to 120V for the lower voltage model.