Batteries stackable?

[RC-Monster Mike]

True. I always recommend a single system. The efficiency is a reason, along with the weight and ability to troubleshoot a problem. In a single system, if something goes wrong, it doesn't work. Pretty easy to diagnose! In a dual system, if one system is working and the other is not (you might not notice), you will most likely blow the controller that isn't working (and it could be a simple connection causing it not to work, but it will likely be overloaded with the power reversing throught the tranny, as a brushless motor acts like a generator).