Can I run 2 different batteries at the same time. 6.0v with a 7.4v lipo

[Jamesv78]

In trying to use the stock 6.0v battery for the receiver and throttle/brake and a 7.4v lipo for the steering. Can it be done with out the use of a BEC or is there a better way of doing it

 

[Phill2]

The only answer I can give is I wouldn't do it.
Mixing batteries usually ends up with a fire.