MMM V2 Bec 6V possible?
 

Im wondering if any future update allow to change voltage to 6V instead of 5.5V or is that impossible? I've always run my external bec with MM in 6V, i got better servo response and more airflow for the 5v fan since it make it spin faster.

i dont really think that .5 volt could make a big difference????

Patrick has stated in the past that you can send back your MMM and they will mod it for I believe a nominal $20 to be 6v.

lol, for just a few $$$ more, you could get a CCBEC, which is much more adjustable, has higher current, and won't cost additional to re-adjust it in the future if you change your mind.

That's true. But, then you got all the extra weight of the CC BEC. I think it's like 8 grams or something like that... :whistle:

So this means that I have to send my 3 month backordered MMM once I have it (cause it still backordered) just so I can use 6V? Im on the opposite end of the world and I have to wait another 2-4weeks....I think i'll just settle for a BEC...good thing I saw this thread.....

im using mine at 5.5 and do not notice a difference. but the question is WHY was this decission made to go to a lower voltage than is commonily used for racing?

lol, yeah, that's a lot of weight. 8g is 0.28oz. That small amount of weight can be made up just by better ESC placement and then trimming a little off each of the motor and power wires. :smile:

The 5.5v of the MMM performed better then my 6v hump packs.

From another forum
Oh well, what's half a volt.

well looks like i'll have to live with 5.5v, dont want the extra bit of ccbec weight...but im gonna put a metal wheelie bar on it instead...hehe

Im using a servo that can operate between 6-7.4V (robot servo). I don't want to end up killing the BEC unit on the MMM (not sure though if it will but that risk of waiting again is great)

how do you disable the MMM bec? take out red wire too?

yep. :)

that's the normal way, to remove the middle red wire.

my guess is that the fan will no longer work?

No... technically this doesn't disable the bec it just stops the BEC powering the RX and the servos.

The BEC would still power the fan and the brian board - although easy to to remove the fan plug from the bottom of the MMM and rewire to run off of the RX / UBEC.

The MMM does not have an opto mode which would mean the ESC brian board is powered from the RX and the red wire is left in.

I just took my MMM apart and I could not find a brian board anywhere. :wink: :lol:

Brian, do you think the MMM BEC unit can handle the Robot Servo (6V-7.4)?

Considering the torque and speed of a servo is lower at lower voltages, I would technically say yes. Patrick can provide more info, but I would feel a bit leary of hooking up a high current load on the internal BEC. BECs are efficient, yes, but they still get warm with higher currents.

My servo is Hitec HSR 5995

Torque: 333.29oz.in @6V
Speed: .15 seconds/60° @ 6V and .12 seconds/60°(@7.4V) max
Current consumption: 300mA(@6V with no load) 4.2A(@6V lock)
380mA(@7.4V with no load) 5.2A(@7.4V lock)

It has been working on the KoolFlight BEC for a year with no problem but not sure which of the MMM BEC (5.5V) or the CCBEC can be the better option///

Well, the CCBEC is rated up to ~7A. However, if it decides to fail, it might take the servo and receiver with it. I have no idea if the MMM bec is based on a similar design and what happens when it fails. If it's been working on the KF BEC, why not keep using it?

BTW: The max current draw @ lock is basically saying a stalled motor. As long as the wheels are fairly free to turn and the servo throw isn't fighting against any mechanical stops or steering limits, the real current should be less, and the average current far less.

got...i guess I'm off to buying another KF BEC..I gave my other one to the guy who bought my MM...

I hope Patrick can reply if the MMM is biased..

Thanks Brian...