Veeeery poooooor acceleration. - RC-Monster Forums

captain harlock · 12:59 PM

Hi, Guys.

I've just tried my truck yesterday with the 1950/10 and 149.18 esc.
The first thing I noticed is that the truck stutterred like crazy befor it started running.
I held the truck with my hand and gave a full throttle to check how good is the torque?
For my amazement, the truck stutterred like crazy again and the controller shut down its current from the motor and then it rearmed itself again meaning its ready to go, but the torque was veerry pooor.

I then took out the controller to see what is wrong with it.
I've checked the soldering connection between the motor and the controller and I discoverred that one of the wires connection is very weak.
I tried to pop it out with my hand and when I pulled it out it came out easily.

It has to be the problem- I said to myself- why the truck stuterred so hard and why acceleration is very weak and why I did not notice any difference in the motor's power when using powers ranging from 3s to 6s lipos. The motor seemed like its running in the same range of RPMs regardless of using 3s or 6s lipos.

Well, what do you think, guys? if I resolder that wire perfectly, will it make a big difference?
I think so very much, but I want to confirm befor proceeding.

Thanks,

Alawi El-Jifri:003:

MetalMan · 10.14.2006, 01:02 PM

A weak solder joint can't handle much current. Torque is proportionaly to the amount of amps, and if few amps are able to get through, then there will be little torque.
Think of it this way - If you have two strings that are connected together by a very thin string, then the whole string is only as strong as the thin string in the middle.

squeeforever · 10.14.2006, 01:22 PM

Yup. I had the same problem...Solder that bugger back on and it should be fine.

captain harlock · 10.14.2006, 02:25 PM

Whew!
Thanks, Guys.

captain harlock · 10.14.2006, 02:35 PM

Another question,

Which frequency should I choose? 9khz or 19khz?

MY setup, again, is a 1950/10 motor, gearing is 51/24, Schulze 149.18 esc and 6s 3700mah Evo20 lipos.

MetalMan · 10.14.2006, 05:17 PM

If I recall correctly, the 2pole motors like lower frequencies, whereas 4pole (and greater) motors like the higher frequencies. So, I think 9khz should do it.

Serum · 10.14.2006, 06:08 PM

Try 9khz first, with mild timing. observe if you like the speed/acceleration. you can always go to 19khz, but observe the temps of the controller. That is the best way to see what it does. It takes more from the controller to work on 9 than on 19 khz.

captain harlock · 10.15.2006, 10:26 AM

My friends,

Considering that the 1950/10 motor makes 1250+ rpms/v and I've noticed that the truck- after fixing the soldering problem- is still stutterring and I also found that when I've connected x2 3s 3700mah lipos, the motor is only running at the same level of rpm when it is connected to a 3s lipo. The motor is actually running on a 3s2p 7400 lipo pack, since I'm using two 3s packs IN PARALLEL and not in series. The controller has four battery leads, but I dont know how to make them double up the voltage of the two 3700mah lipos.
Any ideas?

Also, is it possible that the fact that I'm using only 12.6 volts ( 2 3s parallel) with a motor which needs lots of volts to work at peack performance is what is making the motor stutter and perform poorly?
At 12.6 volts, the motor is only revoluting above 15000 RPMs slightly.

So, what to do?

squeeforever · 10.15.2006, 12:31 PM

Make it into a series adapter........................................... .....................

captain harlock · 10.15.2006, 02:20 PM

Okay,

I found one other factor which might be the trouble behind all the stutterring my truck is making.....receiver pack!!

The receiver pack I'm using is somewhat dead with just little voltage.

Does a brushless truck with an opto coupler controller stutter if the receiver is low in power and nearly dead?

Stupid question, is'nt it?:032:

squeeforever · 10.15.2006, 03:00 PM

I don't think thats the stuttering...Like I said, ITS THE LOW VOLTAGE.

BrianG · 10.15.2006, 05:42 PM

Well, if the receiver pack had low voltage, wouldn't the signal coming from the receiver be low as well? The signal amplitude can only be as high as the supply. Maybe the ESC is having a hard time "understanding" it. Or maybe the receiver is outputting an erratic signal due to the low supply?

squeeforever · 10.15.2006, 06:03 PM

Thats possible...But it will also stutter because of low voltage of the batteries...I guess he needs to do both...

BrianG · 10.15.2006, 06:13 PM

I agree.

I'm not even sure how low a receiver pack has to get before things start acting funny since most of use run BECs of some type. I would imagine that anything over 4.5v would be fine though.

squeeforever · 10.15.2006, 06:24 PM

I would think that it probably wouldn't even act weird, just wouldn't turn the wheels...