brushless motor problem

[yukon635]

So I decided to lighten up my rig and went with a bm9 motor. I am running it in an axial trans with a 87T (I think) spur and a 12 T pinion. Also using a Mamba maxx and a 3s lipo.

The problem I noticed was when I was on a vertical climb and stop in the middle that the truck would roll backwards slowly. Well, no problem, the brake of the brushless motor is just being used BUT when i try to apply forward throttle, it doesnt not stop rolling backwards and go forwards. It just makes a sound like the signal is being recognized but the motor is not turning to make the tires go forwards. Once the truck stops (whether it be hitting the bottom of the hill or me touching the truck and holdingit there), then the truck will progress forward

I tried this in the same scenario but goin forward downhill and try to reverse on the incline. Well that acted like it should. The reverse stopped the truck and it started to slowly reverse uphill.

Is this normal for a brushless motor?? I dont think it is but I could be wrong cause I am a retard when it comes to electronics.

[SVEN]

I had the same problem when testing the GWS 2215. I had to gear down and go to 8 cells to reduce the issue. If I remember correctly it was 12/88 gearing. It looks like you have the voltage part down already, maybe try some lowing gearing.

Just went back and read my results from that thread (budget outrunner testing). I set the throttle curve to 2 steps up in the Y direction at startup, and then linear the rest of the way.

[JohnRobHolmes]

Make sure the start power is on high, and that your battery is in good condition. You might just have to goose it more. Smaller outrunners can be trouble to restart once the ESC looses synch, so try keeping the tires moving on really steep climbs.

Sensorless brushless can naturally have the problem you have when they are starting under heavy load, especially with the motor is small. What tires are you running, and what lipo?

[yukon635]

am am running the losi rock claws. basically a brand new thunder power 11.1v 1320 mah lipo.

I have the start power on high. I am ordering some 90T spur gears since that is the biggest that I can run on an axial tranny from what I have seen.

[JohnRobHolmes]

That will certainly help. Otherwise it just sounds like the motor can't hang with the terrain. I have never liked running 22mm outrunners, except the really long ones.

[Kamikaze]

Hey kev, you need a bm-16!!!!














And a quark!!!

[JohnRobHolmes]

Even just a quark would help most likely. And a Crawlmaster

[Reflection]

850 kv Crawlmaster/Mamba 25 (soon to be a Mamba Max) in my AX-10 with stock gearing and a 2100 mah 3 cell. Smooooooooth and a very nice amount of wheelspeed.

I've not had much luck with the smaller outrunners either. A 30mm motor is a good size. You can get great power from even the shorter motors,which helps with space in the chassis.

[JohnRobHolmes]

Kinda OT, I have a couple of protos for a 2828 size outrunner on the way. It should be the good balance of diameter and power at 8 ounces of heft.

[Kamikaze]

I got false reverses wit hthe bm-9 quark combo, the motor was just to small I guess, never had a problem with false reverses with the BM-16 (or a crawlmaster), even at 17:1!!!

[JohnRobHolmes]

The larger the motor, the easier it is for the ESC to keep it in control. When you go to the larger diameter motors, the increased flywheel effect makes them less prone to stalling as well.

[rocktoy]

I run a BM-9 in my ax-10 with a R2 trans. I have no start up issue's unless I run a pinion bigger than a 11t. I run a 12 on extremely steep stuff it will cog on my and be a PITA to start up. Oh I also run tires just under 6inchs tall and use a 3 cell lipo 2200mah 20C burst.