I'd be careful with "quick charging" and Li-Ion batteries. They don't self balance or equalize like a lead acid or NiMH battery. In traditional batteries, the internal resistance is highest in the lowest voltage cells. When in a series string, as they charge, the resistance drops and self equalizes the string. Ii-Ion batteries work in the reverse. The lowest voltage cell in the string receives the least of the charging power (charge current is constant in a series string but the highest resistance cell has the highest voltage therefore receiving the most power input and heating). This causes higher charged cell to exceed its maximum voltage and destroy itself. They need a balancing circuit to equalize the cells and make sure that no cell exceeds a specific voltage (usually around 4.2 volts per cell). If you do, the excess charging current goes into the overvoltage cell which will quickly heat and destroy itself and possibly ignite the entire pack. If you are supplying power with an external charger that doesn't allow the BMS to initialize the balancing phase, you run this risk.
To be safe, never use a quick charger to go to more than around 80% charge--this should keep an unbalanced cell pair still below the 4.2 volt threshold. Finish the charge with the bikes internal charger and let the balancer do its job which occurs at the very end of the charge cycle with reduced current from the charger. The balancers are basically resistors that are placed across the highest voltage cells by the BMS and shunt the charge current to the lower voltage cells. These resistors cannot dissipate much heat so charging current is usually reduced to less than one amp during balancing---which is why the charger may appear to stay on for a long time at 100% charge if there are cells that are far out of balance. It is also why the bike must be charged from time to time to full charge so that balancing can take place.
It can be done, just play it safe with quick charging. A pack doesn't go out of balance quickly unless there is a faulty cell pair (or in our case a faulty cell in one of the ten that are paralleled). Just bring up the balancing screen on the instrument cluster when using the bikes internal charger to finish the charge and be aware of any segment that appears to be constantly the "low" group. One last point and that is about the bike being aware that external charging is taking place. In EV cars that I have hooked an external charger to, the only way the battery management system knows that a charge is taking place is if it is on. In addition, it needs to think that the power is actually being regenerated from the drive system so that it can look at the amount of power you are adding to the battery for range and percent of charge calculations. In the cars, if the external charge source was between the drive inverter and the battery pack, with the vehicle in the run position, the BMS would just think you were coasting down Pike's peak and regenerating the power--not using an external source. I don't know how the system would react with the Brammo components as I haven't looked at the wiring diagrams to see where the best connection point would be.
