mamba max pro problem

[sikeston34m]

Originally Posted by BrianG

I just did a quick test with various loads with the BEC set for 6v:

5.94v unloaded
5.76v @ 0.48A
5.72v @ 0.64A
5.70v @ 0.95A
5.63v @ 1.87A
4.16v @ 2.77A

Not sure exactly what point the BEC voltage hits its max, but I would say right around 2A. As you can see, the output falls dramatically somewhere around there.

Thanks Brian,

This explains what I witnessed.

A High Torque Servo is likely to draw more amperage than this, especially when fed more than 5 volts. And especially a Pair of High Torque Servos.

Hmmm....... I thought the Internal BEC would be more beefy than this.

Is this a firmware issue? I was running version 1.2, since I read there were motor starting issues with version 1.3.

nope i dont think so i ran 1.24 and still did it , i went back to .22

[BrianG]

I wouldn't think firmware would help or hurt the BEC output; that's more of a design consideration. The BEC circuit is actually quite tiny, so it stands to reason the ouput would be what it is.

[suicideneil]

MMPro V2 already?...

[BrianG]

I don't think it's necessary. The BEC capability is fine IMO for the types of vehicles it was designed for, and the size servo normally found in these vehicles. Making a higher current BEC would require larger components and obviously a larger PCB. If a stronger BEC is needed, it's a simple matter to disable it and run an external one.

[sikeston34m]

I wonder how much the BEC's amp carrying ability is affected by input voltage?

@Brian - What input voltage did you do this testing on?

[whitrzac]

what I'v knowticed is...

spek RX+ jr 650 servo = RX low volt shutdown
spek RX + 617 bluebird servo= same thing...

BUT!! I'm starting to think that the MMp killed one of my spek RXs, it(RX) worked fine on thu when I used my RX8, but when I switched to the MMp it started to shut down and glitch

this was in a t4, 2s, 6.5


also the esc hit 120-130 with the fan not turning on...

Originally Posted by BrianG

I don't think it's necessary. The BEC capability is fine IMO for the types of vehicles it was designed for, and the size servo normally found in these vehicles.

I'm running a hs985mg in a mini ste. This isn't a high torque servo(172oz-in@6v) and without the wheels on it wouldn't be drawing many amps, but I still see voltage dropping below 4v. I had the bec output set a 6v. I'll lower it to 5.5v and then 5v to see what happens.

edit: just tried the 5.5v setting (dx3s reads 5.7v). with the truck on the floor, after turning the wheels 16 times from left to right, the bec drops below 4v once. did this twice with the exact same result. with the bec set at 6v the voltage would drop below 4v after about 5-6 turns.

[BrianG]

Originally Posted by sikeston34m

I wonder how much the BEC's amp carrying ability is affected by input voltage?

@Brian - What input voltage did you do this testing on?

I had it hooked to my PS unit, which is 14.75v.

Originally Posted by whitrzac

what I'v knowticed is...

spek RX+ jr 650 servo = RX low volt shutdown
spek RX + 617 bluebird servo= same thing...

BUT!! I'm starting to think that the MMp killed one of my spek RXs, it(RX) worked fine on thu when I used my RX8, but when I switched to the MMp it started to shut down and glitch

this was in a t4, 2s, 6.5


also the esc hit 120-130 with the fan not turning on...

The Spek receiver is pretty solid. I find it hard to believe it is dead. What I have noticed however is that they seem to be pretty sensitive to any noise.

Originally Posted by drkdgglr

I'm running a hs985mg in a mini ste. This isn't a high torque servo(172oz-in@6v) and without the wheels on it wouldn't be drawing many amps, but I still see voltage dropping below 4v. I had the bec output set a 6v. I'll lower it to 5.5v and then 5v to see what happens.

edit: just tried the 5.5v setting (dx3s reads 5.7v). with the truck on the floor, after turning the wheels 16 times from left to right, the bec drops below 4v once. did this twice with the exact same result. with the bec set at 6v the voltage would drop below 4v after about 5-6 turns.

Well, judging from my tests, I bet those servos are pulling over ~2A. It might help to put a capacitor on an unused servo channel, something like 10,000uF which will help provide that extra boosts when current spikes.

I don't have any problems when driving the truck, just the occasional 'beep' from the dx3s when voltage drops below 4v. It's ok for my 4.8lbs mini ste but I also want to use the mmpro in a 7lbs e-maxx.

edit: I'm running 6s

[sikeston34m]

Originally Posted by BrianG

I just did a quick test with various loads with the BEC set for 6v:

5.94v unloaded
5.76v @ 0.48A
5.72v @ 0.64A
5.70v @ 0.95A
5.63v @ 1.87A
4.16v @ 2.77A

Not sure exactly what point the BEC voltage hits its max, but I would say right around 2A. As you can see, the output falls dramatically somewhere around there.

There are several other factors of actual running that will affect these results.

If your tests were quick, the ESC was not up to operating temperature. With the ESC powering a drive motor and carrying an amp load, the BEC circuit temperature will rise just from the heat being given off by the Power board.

What are the results on 6S input voltage?

After signing up to be a Beta Tester for these units, I'm sure several thousand people signed up before me.

In Actual running, it was noticeable, the glitching really didn't set in until after 10 minutes or so. This leads me to believe, temperature affects BEC output.

The "Glitch" would show itself in the form of:

If I were turning, the steering would momentarily stay in that position or the truck would not turn when going straight.

Afterwards, I disconnected the steering and checked for binding. There wasn't any binding.

[suicideneil]

Interesting...

I have seen on my many travels that for high powered servos, esc manufacturers recommend running an rx pack (of sorts) wired to the servo in series ( I think) via a y-splitter, so that the esc was only really providing the signal to operate the esc, with the rx pack providing the go-juice; rather like having a glitch-buster capacitor plugged into the rx.

Not the most compact or elegant solution, but one of three options along with the cap or running an external BEC..

[ta_man]

Originally Posted by BrianG

I don't think it's necessary. The BEC capability is fine IMO for the types of vehicles it was designed for, and the size servo normally found in these vehicles. Making a higher current BEC would require larger components and obviously a larger PCB. If a stronger BEC is needed, it's a simple matter to disable it and run an external one.

I find this rather disappointing. For me, a major selling point of the MMPro was the switching BEC good to 6S (though I only planned to use if for 3-4S). If I have to use an external BEC anyway to run a decent power servo I might as well just just an original MM and the BEC (for 3-4S).

(Reminds me of my Havoc 3S, which, on 3S, needed an external BEC to run a good servo.)

[Happywing]

I've only run my MMP in 1/10 vehicles with servos that are suitable for said 1/10 vehicle. No problems at all. The MMP is made for 1/10. Usually, 200 oz/in servos are not necessary for 1/10. The MMP is fine in the environment that it was designed for.

the mini ste is 1/12, and the servo I use is <200oz-in.