For on the road, how nice would a 2-5 amp/10 amp charger be. Run 10 amps bypassing the bms, to 90% charged. Then switch to 5 amps for the balancing if you want it.
Don't know any way to do it now, besides carrying a second 2 amps charger. But then, you should be able to leave the balancing charger at home.
BMS battery is one place to get larger chargers. Reliability? Low shipping rates? Uhhhh.......
Can you parallel EM3's 5 amps chargers? Or split your pack to charge each half at 5 amps?