Overcurrent? No..... - RC-Monster Forums

marcus · **Overcurrent? No..... -** 02.27.2008, 04:43 PM

Losi 8ight
8XL motor
4S 4100
MGM9032 (Default settings on all but lipo selection)
14t Pinion
Stock spur

First run out today just up the street.

Firstly, the speed of the thing is less than impressive, no feeling of "OMG" at all. I liken it to a Nitro motor running too rich. 30mph perhaps.

Next thing, more worryingly, if I grab full throttle quick, the ESC shuts down. Will only accept WOT if I feather it up. It's like an overcurrent shut down.

I cannot accept that this motor/ESC combo will overcurrent on 4S with this gearing, which is arguably too low for track work anyway.

Any ideas?

BrianG · 02.27.2008, 05:49 PM

What brand of batteries are you using? A motor will pull as much current as it can to get the motor to the speed the throttle is set to and if the batteries aren't up to the task, it can cog, stutter, or be slow.

jhautz · 02.27.2008, 06:06 PM

sounds to me like the problems that some have been reporting on the MGMs. As soon as you give it to much throttle it goes into overcurrent safety and limits the rpm. an 8xl on 4s should be a fairly powerfull setup. More powerfull than any nitro thats for sure.

Check this thread. It may have some info you can use.
http://www.rc-monster.com/forum/showthread.php?t=10153

02.27.2008, 06:51 PM

Quote:

Originally Posted by jhautz

sounds to me like the problems that some have been reporting on the MGMs. As soon as you give it to much throttle it goes into overcurrent safety and limits the rpm. an 8xl on 4s should be a fairly powerfull setup. More powerfull than any nitro thats for sure.

Check this thread. It may have some info you can use.
http://www.rc-monster.com/forum/showthread.php?t=10153

Ditto, I second that emotion.

J.

marcus · 02.27.2008, 07:00 PM

Quote:

What brand of batteries are you using? A motor will pull as much current as it can to get the motor to the speed the throttle is set to and if the batteries aren't up to the task, it can cog, stutter, or be slow.

FlightPower 4100 EVO2 35c/50c

02.27.2008, 08:39 PM

That doesn't sound right at all. I know my 8xl gets hot, but it hasn't thermaled yet. Granted, I'm running a MM and Zippy 4s batteries. I have a 15t pinion in mine, but if you look at my thread and compare speeds. Mine isn't as stupidly fast as my Revo, but I think it would be just fine on a track.

jhautz · 02.27.2008, 08:46 PM

Its that speedo I'm betting. Try setting it to race mode and NiMH battery type. That should help with the over current kick out. If it works in race mode (or at least works better) then you can be sure its the same problem the others were having. If what they found in the other thead is right then a shipment back to MGM will be in order to fix it.

On 4s with that setup you could just run the Mamba Max with a 25mm fan on the heatsink and you should be fine. The MM can handle the same amount of (or more) current as the 90amp MGM. The MGM you have would be great for a very high voltage setup (8s or 10s lipo) But you dont need that in a buggy. the 4s you have is plenty.

Finnster · 02.29.2008, 12:58 PM

I def think you are overcurrent. The cont is 90A, but the burst current is only 100 or 110 IIRC. The Esc is designed for hi voltage, and the FETs they use do not have really high burst ratings like lower V escs (compare the specs to the 16018.)

A 8Xl on 4S will def pull above 110A, prolly 120A+ depending on the gearing in bursts for your truggy. Basically is is not the right controller for your setup.

You need to either use a different controller (like the 16018 or Quark or whatever) or get a different motor and batteries. To make the power you want and keep that controller happy, you prolly want to have an 8S setup ( ie a 8S 2500mah pack) and a ~14XL motor. The upside to the latter is it will be a much more efficient setup. You will have very cool temps even with a cheapie motor, and you will have longer runtimes as you are wating less battery power to heat.

crazyjr · 02.29.2008, 01:04 PM

I had a 7XL in a Gmax and a 9XL in a G2R, both could pull 120amps on 4 or 5s. I know this is a buggy and mine are way heavier, but throwing my experiences with fegaio's to help.Not really sure how direct drive and lighter weight would effect the setup. I have to agree with the experts though, that the esc is going into protection. You're battery should handle it