jwalk33

Any one know if this motor can handle a 120A ESC on a 4000-5000mah 3s lipo? Associated Reedy 540-SL 6100kV Brushless Motor

I'm looking for a 2 pole brushless motor that that can handle 3s lipos and 120A ESC for speed runs. The ESC can only run 2 pole. The motor needs to be under $60 which is probably not possible.


Thanks guys!
Jwalk33

EXT2Rob

My Feedback: (1)

I believe it's the other way round....can the ESC handle the MOTOR?  I don't see why not.  120 amps is a boat-load of power.  A 6100kv motor is gonna pull more current than a 4000kv motor.  But I think both should be fine together.

Foxy

Its a question of rpm and frequency. Can the ESC pulse fast enough to exceed (6100*12v fully charged) 73,000rpm? Can the motor stay in one piece at that speed? I dunno. Maybe?

Scottgir

Short answer....YES.

The 6100 is a standard motor. You'll be lucky if you pull 70 amps with that motor, and I'm being VERY generous.

The XP 450 ESC Reedy made to go with that motor is a 45 amp esc and is rated to handle that motor on 2S max.

Foxy

Scott, I don't think the issue is going to be power, I think it's going to be rpm. 73,000. That's a fair spin.

t-max97

My Feedback: (9)

The motor can handle a 10,000,000,000,000,000,000 amp esc, the amp rating isn't what the esc sends to the motor, it's the max amps the motor can draw from the esc. You need to see how many amps the motor draws at max draw and get an esc that rated a little higher to be safe.

Sixtysixdeuce

This ^^^^

Think of it this way: Your car has a 500-800A battery (maybe more), but no wire/cable in your vehicle can handle that many amps (not even 4/0 cable can take that much). They don't need to, though. Your highest draw is your starter, probably 120-140A if it's working properly. Therefore you do not need cable or a power distribution center that can handle the battery's max amps. Each circuit is designed around the max draw under normal conditions, and fused/breakered in case that draw is exceeded by a faulty component or short to gound.

In short, the amps consumed are dictated solely by the unit being powered, and if the unit is drawing more than the circuit can handle (assuming power source can match that demand), you'll let the smoke out.

Conversely, if the power requirement of the unit is more than the rest of the circuit (including power source) can provide, you may damage the device. Try running a power saw on 300' of homeowner grade 18ga extension cord; you'll burn up the motor in no time (wire length increases resistance)

Foxy

jwalk33

Ok,

I have 5000 mAh 45-90c burst/discharge lipo, 6100kv Reedy brushless motor, and 120A brushless ESC. However the battery seems to drain exremly fast in about 5-10 minues. Prior to this setup, I was running the same battery and ESC with a 4370kv brushless motor and the run times were much longer, about 45 minutes.

I am charging the battery at 5A as I've always have and it takes about 50-90 minutes to fully charge depending on how much it has been drained, I am basically running the car on the street/parking lot as I've done always.

Can someone please explain to me why this might be? Also, it appears that the Turingy 4370kv motor "looks" as if it was a bit faster than the 6100kv Reedy which is a shock to me. Maybe the Turingy motor just has insane torque due to lower turns because I can literally pull wheelies at will while hitting speeds at about 50mph and possibly faster. Shredded about 4 sets of tires with the Turnigy motor easily, not so much with the Reedy motor.

I raced a Jato 3.3 with 2speed transmission that's blazingly fast and beat it more times than not running the length of a street block. I honestly only loose because I can keep the front wheels down even wih the wheelie bar so low that the wheels on it drag on tthe ground, spin out, or having to ease on the throttle too gradual which gives a really slow start and I have to catch the Jato later on down the lot while on 2 wheels lol but serious. Thinking I will need foams

I have the same gearing as before too.


Thanks All!
Jwalk33

cumquat

you kind of answered your own question. you installed a more demanding motor, so your runtimes will drop. you pull 55 amps pretty much continuously from a 5 amp battery and it'll go flat in 10 minutes. your 4370 likely pulled less current at peak and because it wasnt tasked as much so it wasnt pulling it's peak for very long meaning longer runtimes.

jwalk33

Some what makes sense and basically what I was guessing. Would charging at lower amps give more run time? Does this also explain why the Reedy motor doesn't seem faster because the battery isn't able to produce the needed power?


Thanks,
jwalk33

cumquat

charging at lower amps will just take longer to charge, it wont effect the runtime. when you switched motors, did you change gearing? if you didnt, that'd be the reason it seems slower. the motor probably doesnt have to power to move the vehicle beyond a certain speed and it'll definitely take longer to reach that speed. what vehicle are you running?

jwalk33

I am running a MRP Ripper II with an all metalBrushlessDuratrax Evader gearbox/transmission; my gearing is 32p 16t pinion and 56t spur. I went with this pitch because I was chewing up spurs using 48p.

Guess I'll have to wait to test different gearing because these are the only 32p gears I have on hand for testing and they've hold up very very well to my surprise so far.


Thanks,
jwalk33

cumquat

presuming you're running 4 inch tires your old motor had a theoretical top speed of 63MPH, this new motor's theoretical top speed is 88MPH. neither speed accounts for ballooning which can add 10MPH or more pretty easily. i would switch to foam tires front and rear and swap out to a 20t pinion. this puts theoretical speed at just under 72MPH and should cut way down on rotational mass, meaning it should be reachable.

jwalk33

Will do and post back with results, thanks cumquat!


jwalk33