Hi,

Different of batteries that we can usually install in parallel (the voltage equalizate on both cells, energy transference) a BEC can't "transfer" the energy btwn each other. We can't say "will burn right now", but will certainly damage the RX and/or BEC. On all my TZ85 i unplug the red wire and know a lot of people that do the same. Instead you can leave all TZ85 BEC disabled (switch off) and use a external BEC.

Guilherme