Does anyone know where I can find information/specs for the HCHII battery pack? (ex. how many cells, volts per cell). I'd also be curious to what effect a damaged cell has on the IMA system. Thanks.

 

The battery pack consists of NiMH cells. Since the pack is rated at 158V/5.5Ah and NiMH cells have a nominal voltage of 1.2V, there are about 158/1.2 = 132 cells in the pack.
Looking at the capacity (5500mAh), the cells could very well be D-cells. You can already find those up to 9000mAh. I don't think they could be C-cells, since I have not seen any over 4000mAh yet.

The HCH-I pack is 144V so it has 144/1.2 = 120 cells in series.

Since the cells are in series, if one cell would brake and be 'open' the pack would be dead.
If one cell wouldn't want to charge anymore, the voltage of the pack would drop, and the total maximum energy that can be stored in the pack would be lower.

Some more numbers for the interested:
The pack's capacity is 158V * 5,5Ah = 869 Wh
The electric motor (at full load) is 15 kW
If you would continuously run full assist with the electric motor, this could last for 869/15,000 = 0.0578 h * 60 = 3.5 minutes. Not that it would ever happen, but it gives an idea of the capacity of the battery pack vs. the capacity of the fuel in your tank.