External discharging with the charger, and old school heat hooked up (automotive brake/turn signal bulbs) and prettier(?) resistors. The H6 Pro can also do regenerative discharging if you're into that (discharge battery's energy and put it into another battery).
The bulbs are rated at 2.2 amps...
Just search for "charger (insert cell count)S balance lead extension". I believe I ordered Apex RC brand. Seems like good flexibility in the wires & insulation.
Hota's D6 & H6 Pro chargers
It seems like every couple of years I upgrade my chargers for whatever reasons. Most of the time it's because of wanting more power or a feature on the new generation of chargers out there. I didn't want to go all out, and spend the money on the iCharger that I have...