Mamba Max Pro and Digital Servos
09-23-2010, 08:32 AM
#1
Mamba Max Pro and Digital Servos
I have heard bits and pieces of "possibly" the MMP burning up digital servos, and that you should run an external bec? Does anyone know more about this or if it is even true. I just ordered one and plan on using a digital servo, any help on this would be great since I'm a nitro guy!
Thanks
Thanks
09-23-2010, 09:18 AM
#2
It's SOME digital servos that pull to much juice and make the internal BEC cutout which in my case cost me a chassis and top plate on my T4. So buy the $125 speedo, the $25 BEC, and the $12 glitch buster to run something that should have worked in the first place. 
Just be careful. I've had a speedo and BEC "on the way" to me for over a week now with no response.
Just be careful. I've had a speedo and BEC "on the way" to me for over a week now with no response.
09-23-2010, 12:12 PM
#3
Not all digital servos, just some. For example the hiTec 7955TG needs one. Simply won't work without it. They're easy to install though as long as you have room on your receiver and know how to solder.
09-23-2010, 12:39 PM
#5
Tech Apprentice
I just ordered a sc10ft and planned on getting a MMP and Novak ballistic 10.5.
Might hold off on that now until I know whatever radio I choose won't be an issue.
Might hold off on that now until I know whatever radio I choose won't be an issue.
09-23-2010, 12:56 PM
#6
Because I was curious (and bored) I called Castle Creations and talked with Bernie in support... who by the way has forgotten more about electrical engineering than I'll ever know. Scary smart dude.
Anyway, the problem with digital servos is that they have a higher average amp draw than analog servos, and a *much* higher amp draw under load/at stall. That's the price you're paying to get the performance you get. The voltage doesn't matter, it's the amp draw that's killing you. The internal BEC cutoff on the MMP for instance is between 2-3amps depending on your power source (2s, 3s, 6s etc). Some receivers can't handle the amp load and will fry, or your internal BEC cuts off. According to Bernie, changing the voltage in the software from the default 5.5 to 9 as D-money mentioned makes no difference to the max amperage draw of digital servos at stall. Also, some servos will draw a higher average amperage during longer runtime as the servo components heat up.
Hopefully someone with a better grasp of the technical details will chime in but that was what I took away from my conversation with Castle.
So if you want to run a digital servo and are having cutouts or issues, either use an external BEC or move to a servo with high speed/lower torque (or lower speed/higher torque) for your particular needs. Or go back to analog and not worry about it.
Anyway, the problem with digital servos is that they have a higher average amp draw than analog servos, and a *much* higher amp draw under load/at stall. That's the price you're paying to get the performance you get. The voltage doesn't matter, it's the amp draw that's killing you. The internal BEC cutoff on the MMP for instance is between 2-3amps depending on your power source (2s, 3s, 6s etc). Some receivers can't handle the amp load and will fry, or your internal BEC cuts off. According to Bernie, changing the voltage in the software from the default 5.5 to 9 as D-money mentioned makes no difference to the max amperage draw of digital servos at stall. Also, some servos will draw a higher average amperage during longer runtime as the servo components heat up.
Hopefully someone with a better grasp of the technical details will chime in but that was what I took away from my conversation with Castle.
So if you want to run a digital servo and are having cutouts or issues, either use an external BEC or move to a servo with high speed/lower torque (or lower speed/higher torque) for your particular needs. Or go back to analog and not worry about it.
09-23-2010, 01:14 PM
#8
Tech Fanatic
iTrader: (15)
Amoeba is correct, I delt with this problem when I bought a MMP as a temporary esc. The problem is the amp draw when the servo's try to re-center themselves causing the high amp draw and the shut down of the internal BEC.
The solution is simple and cheap, you can get external capacitors that plug into your RX, Spektrum makes one that's $7, LRP makes one for $8 and Novak makes one that's a little bigger for like $12
YOU DO NOT NEED AN EXTERNAL BEC, just the capacitor that plugs into the receiver!
Not all ESC's have this issue, I'm back to running LRP's in both of my cars and they don't have this issue because they have a true 3A BEC and they also have a capacitor soldered in on the esc. There are a few other esc's that use the external caps, novak being one of them as well.
DO NOT RUN YOUR SERVO @ 7v! KEEP IT AT 5.5v - 6v the factory default. This doesn't fix the problem and will just fry or drastically shorten the life of your servo! Unless you are running a high voltage heli servo which you could just wire directly to the battery.
So until Castle and a few other ESC companies get with the program, people will keep buying "Glitch Buster" Capacitors to solve this problem.
You can also make one yourself if your feel like saving a few bucks. It's cheaper in my mind to spend the $7 and save yourself the time of making your own.
Feel free to PM me if you have any questions.
The solution is simple and cheap, you can get external capacitors that plug into your RX, Spektrum makes one that's $7, LRP makes one for $8 and Novak makes one that's a little bigger for like $12
YOU DO NOT NEED AN EXTERNAL BEC, just the capacitor that plugs into the receiver!
Not all ESC's have this issue, I'm back to running LRP's in both of my cars and they don't have this issue because they have a true 3A BEC and they also have a capacitor soldered in on the esc. There are a few other esc's that use the external caps, novak being one of them as well.
DO NOT RUN YOUR SERVO @ 7v! KEEP IT AT 5.5v - 6v the factory default. This doesn't fix the problem and will just fry or drastically shorten the life of your servo! Unless you are running a high voltage heli servo which you could just wire directly to the battery.
So until Castle and a few other ESC companies get with the program, people will keep buying "Glitch Buster" Capacitors to solve this problem.
You can also make one yourself if your feel like saving a few bucks. It's cheaper in my mind to spend the $7 and save yourself the time of making your own.
Feel free to PM me if you have any questions.
09-23-2010, 01:14 PM
#9
09-23-2010, 02:09 PM
#11
I'm running that exact servo & ESC (with a Ballistic 4.5HV) on my Jammin SRT10. No issues at all. On my Hyper I'm running the JR9100S +same motor & ESC, again with no issues whatsoever.
09-23-2010, 05:33 PM
#13
I think I had a bad esc (or TWO).
09-23-2010, 06:42 PM
#14
NOW, the only reason that a capacitor 'could' work would be a internal BEC that was allowing more amperage; but not sufficient to work without some form of amperage stabilizing 'help'.... AND, I truly believe that (it stands to reason that) the degree of amperage available to receivers probably does vary among MMP units. Northing more complicated than production tolerances would be my theory....
BUT, they're good controls; reliable and providing excellent performance! Adding the cost of a BEC to them should not 'break the bank' although it was an expense that wasn't planned....
09-23-2010, 06:51 PM
#15
It's SOME digital servos that pull to much juice and make the internal BEC cutout which in my case cost me a chassis and top plate on my T4. So buy the $125 speedo, the $25 BEC, and the $12 glitch buster to run something that should have worked in the first place.
Just be careful. I've had a speedo and BEC "on the way" to me for over a week now with no response.
Just be careful. I've had a speedo and BEC "on the way" to me for over a week now with no response.