Brushless Maxx hesitates - RC-Monster Forums

steve050773 · **Brushless Maxx hesitates -** 04.29.2006, 11:18 PM

I have a supermaxx with a 9920/1940 7 turn hi amp, running a UBEC, spektrum, and 14 ib3800 cells with deans. The motor is wired to the controller using 3.5mm plugs. Motor has a heat sink, ESC has a fan.

The problem is hesitation in mid acceleration. Its almost like cogging yet its after the truck is well under way. Its hard to describe, but it looks like the hesitation you might see if a truck were shifting from low to high. Just a momentary pause and then its off. Of course, my truck is a single speed so thats not it. This has happended with gearing 14 to 16 on the pinion/51 spur.

Any thoughts on what might be the issue?

infinite_loop · 04.29.2006, 11:44 PM

hmmm..for some reason..i had this same exactly problem, but on stock titans w/14 cells ib3800s.

I solved it by using a receiver pack.

You have a UBEC, so that's probably not the problem. But perhaps you should try a regular (nimh) pack, just to eliminate the chances of that being it...

Mike.L · 04.29.2006, 11:50 PM

is your e-maxx running hot. because there are some chances of the cut of to that?
but most of the time its at full?

squeeforever · 04.30.2006, 12:47 AM

it actually might be your ubec. sometimes they cause weird problems. try moving it somewhere else.

Serum · 04.30.2006, 02:56 AM

Yeah, i would try a receiver pack to start with.

neweuser · 04.30.2006, 02:58 AM

Mine does the same thing at full throttle. i tried redoing my batts and adding a ubec, droping the receiver pack, and will test tomorrow and let you know if it cured it. my ib's were done in a stick pack...

Tom F · 04.30.2006, 12:53 PM

What about gearing? Have you tried gearing a bit lower?

That would reduce the current draw - a 7 turn 1940 must pull a sick ammount of current at the best of times - if it's over geared, i shudder to think lol

Check things are nice and cool - packs, heatsinks etc

Serum · 04.30.2006, 01:25 PM

Try a receiver pack to start with first.

mmdooley · 04.30.2006, 10:26 PM

I am running 16 GP3700's on my e-maxx and a 8xl and ubec and it runs great. If your motor draws alot of amps you might try bigger batteries ( more cells or lipo's)
Good luck

squeeforever · 04.30.2006, 10:39 PM

Its not his batteries. Chances are its the ubec. sometimes they cause interferance issues.

mmdooley · 09:48 PM

Is there a way to test to find out. No matter where I mount my ubec it works fine. Oh yea, You have to mount the ubec backward, Point the flat side toward the electronics. Are you doing that Steve?? Here is a pic.

steve050773 · 05.02.2006, 07:51 AM

Guys - thanks for all the responses. I have not had time to test this yet. I am not running the UBEC like mmdooley (I have it flat on the chassis towards the rear) so I will try that first. Then, if necessary, I'll give a spare receiver pack a try.

I'll post an update this weekend.

Steve

neweuser · 05.04.2006, 01:28 PM

For me, I dropped the receiver pack and and redid the batts from stick to side by side...tested, no probs at all. I do have a very short receiver wire though which i think is my problem when i get too much distance. Does it happen far away from you and near you? Or just far away?

Nick · 05.04.2006, 02:41 PM

UBECs are awful. Never had any luck with them.

Sylvester · 05.04.2006, 04:21 PM

Quote:

Originally Posted by Nick

UBECs are awful. Never had any luck with them.

This is not true, just because you didnt have any luck with them doesnt mean you can say they are awful, lots of forum members including me have glitch free running with a UBEC...