I've been reading up for awhile now and from what I've read as long as the
batteries are within 4% of the lowest voltage battery, then no additional heat will be generated and it'll be fine (I will be buying an Efest Luc asap though and another set of
batteries for overall longer battery & mod life). The
batteries have been charging for 6 in a half hours and they're reading 3.93, 3.86, and 3.93 with a 2 amp charger. 4% of 3.86 is 0.15 and they're only currently reading a 0.7 difference so I believe I will be completely fine using the on-board charging for 2 weeks before buying an external charger.
P.S. The RX200 won't fire if the voltages of the batteries are out of balance by .3 or more.
P.S.S. Thank you all for the informative replies and swift help, I really appreciate it