[Unsullied_Spy]

It should run it just fine, but disable the BEC (either unplug the red wire from the Rx wire or get a short servo wire extender and remove the wire from that so you don't have to mod the MM). Once you do this you'll need an external BEC such as the CC BEC, Mike sells a few different BECs.

The internal BEC should would on 4s A123 as the voltage isn't much higher than 12 cells NiMH but the farther over 5 volts (at least, I think it's a 5v BEC) you get, the hotter the BEC will get and on 4s A123 you could possibly burn up the internal BEC.