Lowest operating voltage for MMM and MMP
 

Right now I have the MMM in my TC3 and I bought some of the Turnigy 2s Life packs to run. Now I am not sure if the voltage will be high enough? I know the other thread said 2s lipo was fine on the MMM, but what about 2s LiFe? It would follow that to run on 2s lipo the MMM can run down to 6V when using a 3V/cell cutoff, but I plan on running the LiFe packs at 2V/cell cutoff. So the range of 6.6V-4V seems too low now.

My goal is to get an MMP once they become a little more available. Will the MMP run on 2s LiFe? I know they are releasing the 1S version of the MMP, but I'd rather buy the regular one if I can.

So overall, what is the minimum voltage to run the MMM and standard version MMP.

I'm not a proffesional but I would make an educated guess and say that 4.8V is the minimum. I know it's not the same but my Mamba 25 will run just fine on a 4 cell nimh pack but after a couple minutes if I try asking to much of it, full throttle starts, it cuts out for a moment as the large current load drops the voltage.

Have used the MMM and MMP on 2s Life myself without incident. Just make sure your LVC is off.

Maybe it will make the most sense to go with the 1S version MMP and an external BEC.

If you are running 2s LiFe, I would either set the BEC to as low as possible (in the MMPro), or use an external one. There is ~1v dropout voltage needed. When a 2s Life is fresh (~6.6v), a 5.5v BEC is fine. But when under load and when they start to discharge, batt voltage will drop and may cause the BEC to cut out.

I've been running 2s life(2s1p A123) for a long time with no problems in the MM, MMpro, RX8, Quarks, LT-120+200. The MMpro and LT bec are set at 6V and I don't have dropout issues. I even ran the RX8 in my heavy GTP on 2s2p A123 with no problems.

The MM and Quark (old XXXB line) use linear regulator, which have a lower dropout (~0.3v), so that makes sense. But I'm sure you realize that the supply voltage HAS to be somewhat higher than the BEC voltage, or the BEC voltage will drop. If it drops low enough, it simply shuts off.

The RX8 and MMpro hasn't shut down on my yet. The RX8 in the GTP works, but the steering is a bit slow. Not a problem really as you are not going that fast anyways with 2s2p A123. The MMpro is in my rustler running those RC4WD beadlocks and Imex claw dawgs in grass. I have no steering problems with that one.

One way to really find out how low my voltage gets, is to slap on the datalogger. It's 26F out right now, so a greater voltage drop with the A123's is expected.

I tried to run 4s1p in a rustler and an evader though an MM with CCBEC, the BEC was constantly cutting out under load and it was driving me nuts (the ~1sec boot time of the Rx caused me many accidents), lucky that linear reg in the MM is a tough little guy because I have not problems after I got rid of the ext. BEC :p I can't imagine it NOT being a problem with the ridiculous V drops you get with LiFe... Using a cap on the Rx fixed the problem in the evader, but for some reason no matter how much cap i added to the rustler the problem was still there *shrugs*