Pro4 won't turn until I give it a push

[t3yf5g]

I am running a Pro4 3300kv with a brushless hobbies LT4 and 3s 40-50c battery. I have to give my rig a push before the motor starts to run. Not sure what the deal is. Connections are solid, battery is freshly charged and no binding in the drivetrain. I had an old 20c battery that I new was under powered but still experiencing this issue.

[tocsin]

Check your sensor cable. I don't have any experience with the LT4, but starting out from a stop is where the sensors are crucial. Another thing to check might be end bell timing if it's severely advanced or retarded.

What does it do when you try to take off? Does it stutter, whine, or just do nothing? After it gets rolling, does it feel like it's "hitting on all cylinders?" Or does it feel rough? There is a chance you could have an issue with one of the 3 phases in the motor.

If you have access to another ESC, you could narrow it down to the motor or LT4.

[mrG]

With redline and mmp I had adjust the throttle curve to really smooth things out and I ran 4s

[Ty@Tekin]

Try a different ESC and or motor. If the ESC lost a phase it may still run on 2 of the 3 once you push start it.

[ik632]

With my 120a Pro (predecessor to LT4) the deadband is pretty wide and I had to turn my expo up so the initial start was smooth. What happens if you punch it a little to get it rolling then let off or are you having issues when you pull the trigger slow to try and get it rolling?

[t3yf5g]

I have had two experiences so far on this combo. First was with my 20c battery. I would have to pull throttle a few times then it would start up. Then it started to not move on it's own till I give it a push. I was told I needed a better C rated battery. I got one yesterday that is 40-50c. I still have the same result. I can free roll it and don't feel any binding or anything. Once it does take off, it runs like expected.

I did narrow the deadband and have better slow speed. I don't have another ESC on hand and would have to pick one up. Not particularly happy if I have to spend $100 on another ESC.

[mammoth]

IMO a MMP is barely up to the task of running the pro4. I am currently using a MMP with the 3300kv pro4 (in my wraith) and after bashing around on 3s the esc gets quite warm but still acceptable. In my exo with the 4000kv the MMP wasn't up to the task. It would go into thermal shut down after 5 mins of playing then start back up again. I switched the MMp in the exo out to a RX8 and no issues!! When funds allow I will put one in my wraith with the 3300kv just for piece of mind!!!

Remember the pro4 is a very amp hungry motor and if the esc isn't up to the task you will have problems.

[The Violator]

Originally Posted by mammoth

IMO a MMP is barely up to the task of running the pro4. I am currently using a MMP with the 3300kv pro4 (in my wraith) and after bashing around on 3s the esc gets quite warm but still acceptable. In my exo with the 4000kv the MMP wasn't up to the task. It would go into thermal shut down after 5 mins of playing then start back up again. I switched the MMp in the exo out to a RX8 and no issues!! When funds allow I will put one in my wraith with the 3300kv just for piece of mind!!!

Remember the pro4 is a very amp hungry motor and if the esc isn't up to the task you will have problems.

You have gearing issues. I have an MMP in my Losi SCTE which if damn near 1/8th scale and can run pack after pack with my pro4 4400 without issue. Never even gets past 130.

[TLTCrawlin]

What kind of power you running to it Violator?

I was set on MMP/pro 4, and 3s. Glad to see a few more with that setup. Rather fry a MMP (in water or snow/etc) than a tekin ESC (Costs nearly two MMPs)

[t3yf5g]

My gearing is 80/17 48p. The LT4 looks to be a 120a ESC. MMP looks to be 200a. Don't think my battery is hitting 120a.

[Charlie-III]

Originally Posted by Ty@Tekin

Try a different ESC and or motor. If the ESC lost a phase it may still run on 2 of the 3 once you push start it.

+1.

I have little experience with RC type brushless, but I have an extensive background in industrial 3 phase motors.
What you are describing sounds like "single phasing" where a 3 phase motor is less than optimum due to phase loss.
Once the motor is spinning, it "works" but not well.

Since an RC brushless motor is 3 phase AC, it makes sense.
Sounds like either a ESC or motor issue.

[ik632]

See if you can upgrade the firmware on the ESC. I'm running one of the mod firmware on it now and it's much better than the stock blinky firmware. Also, for testing, turn all of the timing settings down as low as they will go. When you get it working, you can add timing back in if needed.

[JohnRobHolmes]

Originally Posted by Ty@Tekin

Try a different ESC and or motor. If the ESC lost a phase it may still run on 2 of the 3 once you push start it.

I would assume there is either a phase out on the ESC, or a bad hall or hall connection if it isn't firmware related. Ty is spot on.

[t3yf5g]

I will put another esc on my list. Maybe I can get a replacement from Stan at brushless hobbies or something. Thanks guys.

[mammoth]

Originally Posted by The Violator

You have gearing issues. I have an MMP in my Losi SCTE which if damn near 1/8th scale and can run pack after pack with my pro4 4400 without issue. Never even gets past 130.

So if I have gearing issues then when I switch esc's I should still be having the same issue correct? Then why is it the I change the esc and no more temp issues. The RX8 dosen't even break a sweat so I don't think its gearing so much as a heavy ass rig and i'm really hard on it!!! BTW if I remember correctly I have 52/13 in my exo which is pretty low I think but i'm not a gearing guru either.

The mmp and 3300kv pro4 in my wraith dosen't have the same issue but I want to change it out for my own piece of mind!!!

[The Violator]

Originally Posted by mammoth

So if I have gearing issues then when I switch esc's I should still be having the same issue correct? Then why is it the I change the esc and no more temp issues. The RX8 dosen't even break a sweat so I don't think its gearing so much as a heavy ass rig and i'm really hard on it!!! BTW if I remember correctly I have 52/13 in my exo which is pretty low I think but i'm not a gearing guru either.

The mmp and 3300kv pro4 in my wraith dosen't have the same issue but I want to change it out for my own piece of mind!!!

Were you running a BEC? The MMP has the poorest excuse for a BEC ever invented. Running it on 3s without a BEC will give cause temp issues. The gearing sounds OK, but in my scte, I run pro4 4400 with 12/42 gearing on 2s. When playing with gearing, going to low can be just as bad as gearing to high as far as temps go.

[mammoth]

No I wasn't running a bec but I'm not running any kind of high torque servo either. It's a XP ds 1015 which is quite weak compared to my other servo's. Now that I actually am paying attention to the spec's of that servo it might of been the issues but still its only just 201.4oz but is fairly quick at .108 @ 6v.

Which if I took my own advice anything @ 200oz or higher should have a bec!!! face palm!!!

[The Violator]

On 3s, it is not really the load on the BEC as much as it is cutting down the voltage from 12.6 to 6. Castle should make a nice connector and throw a BEC in the box with every MMP. Charge an extra $10 ( they are $20, but if they include one with every MMP they sell they should get cheaper. Plus it would probably save them on warranty repairs by the truck load.)

[t3yf5g]

Okay so I pulled the sensor wire and it takes off fine, so that should cross off a phase issue, correct? I even tried another sensor wire. I tend to bash more than try to crawl so I guess a sensor wire isn't really needed in my case. If I want to crawl with a wraith, I'll get another kit and build it for crawling.