Motor analyzer
 

If I have 2 of the same motors with the same fixed timing 45 for example and rpm is equal but one is pulling 2 amps and the other 3 amps which would be the better or faster motor?

Try them on the track?

I would prefer not solder one of them so I can sell it

I am wondering about the same thing. I am not too sure what the Amp reading is telling me. I have a 5.5T and 6.5T. The 5.5T on the Analyzer is reporting higher Kv than the 6.5T, which is expected. But the 5.5T is somehow using 8amp (lower) vs the 6.5T's 9A. On the track, the 5.5T definitely using a lot more than 6.5T with shorter run time...

Amp ratings mean nothing unless there is a load. "6A setting" is a myth. Motor analysers don't apply a load (you need a true dyno for that) although I do find them quite useful for finding a starting point for timing and checking that old motors still work.

To clarify, I believe every manufacturer has a different "peak" setting... for example the Trinity motors tend to perform best at 5.6A but I've seen 3.2A recommended for Tekin motors because they rev up at higher RPM's with both motors performing comparable results even though they are far apart on the recommended current draw settings.



I do agree that a dyno will give the best results but for a quick and easy tune, the motor analyzer has proven very effective and accepted by many seasoned racers in my area. More importantly, the motor analyzer will also help you verify your rotor is shimmed properly and that will also affect the amp draw so if I were in the OP's scenario, I would check to see which motor had the closest gap on the timing reading between all 3 phases and that would be the motor I would keep. If I had to take a guess, I would be willing to bet that the motor pulling more current is probably the faster motor only because the current draw is 3A and below... there will be a point of diminishing return but that would require a dyno to be certain.



If was racing in a fixed mechanical timing class, I would play around with the rotor shim to get optimal timing gap and current draw. Another trick is use use an EMF meter to measure the strength of the rotor, the stronger the magnet the more powerful the motor and theoretically the higher the current that motor may draw. You could also measure the IR of the stator and lowest IR would be the most efficient stator to where you can swap parts between both motors to get the fastest overall motor ;)

To actually answer the question asked…….in theory the motor only pulling 2 amps would be the one yo keep. It’s putting out the same numbers but requiring less power to do so. Should run cooler = more efficient. This is all in theory.

Assuming all else is equal, you have a point, but the low current motor might just have a weak rotor meaning it won't perform well under load.

Maybe repeat the run and put the biggest heaviest pinion you have on it and see if it is still using less current (amp).

A pinion on the analyser isn't really going to do anything at all.

+1

A stator with low IR will in turn reduce the current draw so if possible to swap parts between motors I would use the stator with lowest IR and then run the rotor with the strongest magnet which would in turn pull more current.... so the million dollar question that can't be answered without a dyno is if the stronger rotor pulls more current than a more efficient stator.

I'd take the gamble on the higher draw motor being more powerful, but anything above 5A and then I'd be concerned about efficiency unless it's a TEKIN motor, then I'd target the 3A range.

As the topicstarter refuses to solder wires to it because he want the tabs being unused then the motors have never been used and so never been overheated. In that case I doubt a rotor has lost a significant magnetism.

No 2 rotors will provide the same magnet strength when new, same as the amount of resistance from a brand new stator. With the proper equipment you can test these components individually (without soldering) and cherry pick the parts to get the most powerful motor, then return the less powerful motors. Rather than buying a bunch of motors and testing to see which ones are the best, it would be a lot easier to buy a Trinity 5% Certified motor which has already been tested/certified by the OEM ;)

I’m not sure how relevant This would be for today’s motors, but I recall an old Bud Bartos motor analyzer for brushed motors that used to use a slave motor for load testing. It was crude, but pretty effective.

It’s hard to say how effective a motor would truly be without load. If anything, it just proves how “efficient” it is without load. In theory, the motor pulling fewer amps to achieve equal or greater RPM’s is more “efficient” because it’s pulling less power to get the same output, but as mentioned above, it’s no guarantee that it will perform the same when an actual load is placed on it. Think of real engines. In the real world, there are plenty of examples where a car with an engine with less HP but more torque at lower or mid range RPM’s can outperform cars with greater HP ratings, but lower torque values, or peak torque values that are rated at a much higher RPM.

I also agree that ideally, each manufacturer probably has a preferred “no load” Amp rating that they use to determine their performance. Makes sense, since they each have a different philosophy on how to build them. The Tekin R-Specs are just one example where they favor high torque over high RPM, and where they actually recommend a tooth or two LOWER compared to the norm in order to get peak performance out of them.

Many are overlooking his actual question…….he isn’t looking to break down the motor testing rotor strength and what not. Testing two motors on the analyzer brand new he is asking which one to keep and which one to sell. It’s not a complex question……..🤷🏾‍♂️