Lehner 3080 / 8 Brushless Motor ? fault - RC-Monster Forums

What's_nitro? · 01.02.2009, 12:20 AM

It could be the Shulze is about to go Mt. St. Helens on you and this is a warning... Lets hope not.

_paralyzed_ · 01.02.2009, 02:44 AM

Quote:

Originally Posted by What's_nitro?

It could be the Shulze is about to go Mt. St. Helens on you and this is a warning... Lets hope not.

I haven't heard of any 40.160's having problems. It was the 18.97's that torched, and he mentioned it works fine with the bolido........

mohanjude · 01.02.2009, 02:52 AM

Quote:

Originally Posted by _paralyzed_

I haven't heard of any 40.160's having problems. It was the 18.97's that torched, and he mentioned it works fine with the bolido........

You are right - 40.160 works fine with the Bolido. Just dragging my hels on whether to connect the remaining BK controller to this motor to see if it makes a pretty firework. I was going to take my video camera but didnt get a chance to film the debut run - it would have made one heck of a video or maybe not...

lincpimp · 01.02.2009, 03:05 AM

Motor may have demagged... There is a method of testing the phases against the can to check for shorts, and there must be some sort of resistance spec. If two of the phases are shorted it would act as a brake on the motor, and would also cause some massive current draw thru the esc. I would investigate the motor further. Did you buy it new, or used? Any physical damage?

mohanjude · 01.02.2009, 02:41 PM

Quote:

Originally Posted by lincpimp

Motor may have demagged... There is a method of testing the phases against the can to check for shorts, and there must be some sort of resistance spec. If two of the phases are shorted it would act as a brake on the motor, and would also cause some massive current draw thru the esc. I would investigate the motor further. Did you buy it new, or used? Any physical damage?

I bought the motor off a german seller it looked practically new. If the motor is demagged will it run full throttle on the bench? On the bench the motor draws about 14 amps at full throttle on 39V with no load. The motor heats up slightly but no other issues identified.

lincpimp · 01.02.2009, 03:01 PM

Quote:

Originally Posted by mohanjude

I bought the motor off a german seller it looked practically new. If the motor is demagged will it run full throttle on the bench? On the bench the motor draws about 14 amps at full throttle on 39V with no load. The motor heats up slightly but no other issues identified.

If you run a brushless motor unloaded it can over rev... I would not do that...

Unloaded amp draw is not very useful. Put it in the truck and try running it under alot of load.

Are you sure that it is 20kg? 2.2lbs per kg... over 40lbs? If so then you need a much bigger esc, or a 20s setup. Is the chassis steel?

150 amps at 39v is only 7.8hp, and that is before any losses are considered. That is not enough to run a 40lb vehicle, IMO. You may on the edge with that setup, the motor should be good for 10hp or so, but that esc is a bit undersized.

othello · 03:42 PM

>The other way is to push the truck and then accelerate away

The schulze 32.170 coupled with 11s1p A123 and a 4 pole Neu 1515/2Y (1100kv) was not able to start up the motor properly in a 5.2Kg 1:8 truggy especially in car mode. Heavy cogging from a stand still although the ESC is well overdimensioned in a 1:8 car. Schulze put the A123 cells at fault. We tried it with lesser A123 cell and nimh cells which helped somewhat but we were never able to start the motor up without cogging - we never expected such a behavior from such a high priced ESC. From a stand still pushing the car slightly helped the ESC to overcome cogging and as long as the car was moving the ESC worked flawlessly. An MGM 12545 starts the same setup from a stand still with absolutely no cogging. A small Jazz 55-10-32 ESC has no problem at all with a similar setup.

As you say it does work properly with your bolido motor, one might guess that the ESC has an easyer job to start up a higher pole motor as it will get better/faster a back EMF from the motor when compared to a 2 pole motor. Be prepared that when contacting Schulze everything else is to blame but the ESC.

14A @ no load seems a bit too hefty -> translates to 546 Watt (39V). Which kv version do you use? I have no experience with those big motors but my Neu 1515/2Y (1100kv, 340gr) uses no more than 2A @ 33V.

I looked through the motor data which is hosted on lehners website. Even a 3080/6 is "only" @ 11A (40V) with no load and i think you chose a less hotter wind for your 1:5 car. A 3080/12 is @ 6A (40V) with no load. You may want to contact Lehner on this subject and you may want to try posting in boat forums where you will more often encounter those big Lehner motors.

One thing you might want to try is to start up your setup with lesser voltage (less cells). Maybe this helps somewhat. But in the end it will not be a satisfactory solution (if it works at all) since you will loose top end speed.

othello · 01.02.2009, 04:06 PM

>If you run a brushless motor unloaded it can over rev... I would not do that...

Hmm ... as long as motor kv x Volts does not exceed max allowed RPM there should be no issue revving a motor without load (aside from a fast rise in temperature as there is no airflow aroung the motor). The 30 series Lehner motors are specified up to 50000rpm. 50000rpm / 39V = 1282kv. Even the hottest 3080 motor (3080/5) is below that mark with 1050kv which might tranlate to a max of 1150kv with no load. Still safe @ 39V ... but i suppose you chose a kv well below the 1050kv mark.