at the moment the lights are run off 2* 2p2s 18650 config just now but with the long nights and dark mornings i am looking to increase the run time and also run both the rear and front from a single pack the idea was to have each pair conected to it's own pcb to help with ballancing mutli cell pack
i used to run a set of the ever ready bike likghts with a 12v sealed battery and that was a beast but gave amazing run time
I have the base model - currently the 106B+ - and that does everything I need it to. It'll charge up to six li-ion cells in series. It'll also allow you to reduce the discharge end voltage below 3.0v, and adjust the charge end voltage above 4.2v.
You really don't need much more than that unless you need to charge a higher number of cells in series, or want a charger that stores your charge/discharge info without being attached to a PC, or have some other specific need that the 106B+ does not meet.
If you were looking for a better model, I'd probably go with the 208B. This has higher charge and discharge rates, higher built in discharge power capacity, 8S li-ion capacity, wider input voltage range, and stores log files. I would have purchased this model myself had I had the money at the time.
2nd piece of KK 26650 i got 4533mAh, 1A, discharged to 2.60V set on IMAX B6 (UT-58E measured 2.826V, and i tested this 4X by charging a bit and discharging again to test the exact termination voltage, taking good care of contact resistance).
Get the MKNE then. That is Li Mn. KK can get from cnqualitygoods.com (slightly cheaper overall due to cheaper shipping and 40 cents less for the cell) and int-outdoor.com, MKNE only from int-outdoor but then you need to pay shipping.