How to figure out brushless motor amp draw
 

How can we figure out a motors amp draw rating? Im shocked not to see manufacturer ratings of this like from Tekin even doesnt list it on their site!
I thought these companys used to provide amp ratings. how are we supposed to properly spec out a brushless system without knowing amp ratings? Now my lipo is rated for 850 amps which is very plentiful but I'd still like to know the Tekin truggy motor amp draws.

A motor analyzer will give you all this info plus more. Higher end manufacturers dont really list it if their motors have adjustable timing. A lower timing can draw as little as 3-4 amps and a higher timing will pull 6-7 amps although thats towards end of the performance window.

DISCLAIMER EDIT: This advice is based on 17.5 blinky motor. Nonetheless you need a motor analyzer and side question - is it okay to attach the alligator clips to a motor on the car or do you need to unsolder it?

I think brushless 1/8 motors pull much more amps than 7, regardless of any timing or not.

Under real life loads, all motors will pull more than these numbers. ;)

Sent you a PM.

Nothing to share here?

But yes, there is no way to get specific numbers. The amp draw is depending the weight, gearing, 4wd/2wd tires and the type underground. Only with a datalogger that some high end ESC's have you can see the amp draw.

I've used the "Sams Rev Meter" for this purpose. Simple meter that connects between the ESC and battery. Free rev will show amp draw and you can adjust timing to get the draw you're looking for. Inexpensive little unit that we used for pan car oval.

As soon as you throw a load on the motor the amp draw will go up. It varies with the load.

I understand the amp changes with timing, what I’d like to know from the manufacturer is what is the target amp rating for the motors thermal design. That would take a lot of guess work out of adjusting the timing. My guess is that is known because the factory tuned motors, like Fantom Works, seem to target a specific amp draw for the use case. This is based on observations reading motorlyzer printouts from a few Fantom Works and Slot Machine Certified.

So that you send by PB? Weird idea of using a forum......

But as explained, it is a crap tool, it tells you a load at free spinning wheels, wow. My simple 20 dollar multimeter can do that too, nothing special. It does not tell a thing about the real amp draw while driving.

The thermal limit is the thermal limit. Amps will really only change how fast you get there (if you do). The cheaper non-sciency way of doing it is to slowly crank up timing, make a run, then temp check it. Max temps should be around 160-180 F before the magnets start to get damaged and lose their strength. What motor turn are you running and is this an open or tight track? The longer you are on max throttle, the faster heat will build up. Most hand aligned motors are dynoed for an ideal amp draw/rpm. Too much timing and you are just generating excess heat (too many amps), too little and your losing out the motors total RPM top end. All that is physically motor based. Once you put the motor in your car, you gear it appropriately to the track/driver needs. Also the motor analyzer will tell you the sensor spacing relative to its actual timing - this is usually on that print out. The closer the numbers are to each other the more aligned it is. 44.0-44.0-44.0 on 44 degrees of timing on the endball would be prefect. Real life is usually more like 43.8-44.0-44.1. a crap motor would be 40-45-43 @ 44 degrees on the endball. Fans or air holes can help cool the motor if its getting too hot while still in its "ideal" range.

Your amp draw will fluctuate wildly while driving depending on the load the motor is under at that moment. Kinda hard to say "the amp draw is such and such."

A motor analyser will tell you steady state no load current, which is pretty much the lowest the motor will ever draw. Not the highest.

If the goal is to figure out the thermal impact of the amps, then you want the average amp draw during a run, not the maximum. Run the car, time how long the run went for, and get your charger to tell you how many mAh you put back in to the battery when charging it. Divide capacity used by time and bam, average current.

The goal is not for timing, thermal or heat analysis. I need to know the max amp draw from the motor at its highest level, full burst. This is one of the best ways to spec out a highly efficient brushless system with lots of headroom right? If my battery is rated at 850 amps, and lets say my Tekin motor pulls a max of 150 amps, then I would have tons of headroom from the battery and wouldn't even come close to overloading it.