Question about BEC and MMM
 

I just got my combo for my savage conversion and I use a hitec 9645 for steering and I see some use that add on bec just wanted to see if its neccesary for me or not?
THanks

It's supposedly not necessary, but won't hurt anything to use an external one (remember to disable the internal one by removing the red wire).

My servo seems to be rather slow to so why I was wondering. Have to check into one and price. THanks

Well, depending on which MMM version you have, it could be running at 5.5v instead of the typical 6v most external BECs are rated for. IIRC, V1 and V2 ran at 5.5v, but V3 is running at ~6v.

From some informal testing of several external BECs, they tend to get pretty warm when running at a decent load (~2A+). And those BECs are on their own PCBs, usually with plenty of board to act as a heatsink. The BEC in the MMM is much smaller since the same PCB houses the ESC brains. Plus, the circuit is enclosed so where is that heat gonna go? Some makes its way to the heatsink via the PCBs, but might not be fast or effective enough.

From the same informal testing, I would recommend the Koolflight UBEC, Western Robotics Hercules BECs, or dimensionegineering BECs. The Castle BEC is nice for its current rating and programmability, but tends to be a wee bit on the "noisy" side. But they do work too.

Are these very big? I will look in the monster store but are those listed all sold here?

They're small. I have a dimension engineering sport BEC but I have not use it use with the V3. So far, the built-in BEC works flawlessly.