300bhp/ton Posted February 16, 2018 Share Posted February 16, 2018 Is anyone running the Turnigy TrackStar motors on 3S? Specifically their ROAR approved ones. I recently bought a 13.5T one as my intention was to pump it up to 3S to give a nice spread from mild to wilder performance. However while mulling over my choice I failed to notice these TrackStar motors are only rated to 2S. I’m not sure if this is due to the ROAR approval or not. But didn’t want to fry it instantly with a 3S if it’s actually down to a component limitation. This motor specifically: https://hobbyking.com/en_us/turnigy-trackstar-13-5t-sensored-brushless-motor-3040kv-roar-approved.html Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 16, 2018 Share Posted February 16, 2018 (edited) Don't do it! Mostcomp grade 540's are 2s ratex I've ran a few comp grade 540 motors rated for 2s on 3s.....insane speeds! For all of 10 minutes....... Ran an lrp x20 on 3s for a few outings with no issues,but they're in a league of their own quality wise Stick to a high discharge shorty lipo (90-120c) Edited February 16, 2018 by Fly In My Soup Quote Link to comment Share on other sites More sharing options...
Si Coe Posted February 16, 2018 Share Posted February 16, 2018 It's not that they are comp spec, it's more a max rpm thing. Racing is 2s based anyway. In theory a 13.5t on 3s should be ok, it won't rev more than a 6.5t on 2s. It won't be warranted for 3s use though. Hot wind motors like a 6.5 shouldn't be used on 3s as it will kill them. 1 Quote Link to comment Share on other sites More sharing options...
300bhp/ton Posted February 16, 2018 Author Share Posted February 16, 2018 Yeah thanks. It’s more this specific motor. I wanted a 13.5 for just a mild brushless setup. But then the ability to spice it up when warranted. It’s not in a race Vehcile. It’s in a Konghead. I just didnt realise the TrackStar was only rated to 2S when buying. Never thought to check, else I’d have opted for a different brand. Just wanted to check it’s not likely to grenade itself the moment I plug a 3S into it. Due to whatever has restricted it to the rated 2S spec. Quote Link to comment Share on other sites More sharing options...
300bhp/ton Posted February 16, 2018 Author Share Posted February 16, 2018 Not sure if my calcs are right. But a 13.5 on 3S I’m guessing would be similar performance to a 8.5-9 turn. 1 Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 16, 2018 Share Posted February 16, 2018 (edited) Maths not my strong point dude..... I have experience based knowledge only The motors I put on3s (rated for 2s) where a 6.5, 7.5, 9 Edited February 16, 2018 by Fly In My Soup Quote Link to comment Share on other sites More sharing options...
OllieNZ Posted February 17, 2018 Share Posted February 17, 2018 Looking about most other 540 sized 3100kv ish motors seem to rated for 16-17v so personally I'd run it. The higher the kv the lower the max voltage and higher the current draw for a given RPM. Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 17, 2018 Share Posted February 17, 2018 42 minutes ago, OllieNZ said: Looking about most other 540 sized 3100kv ish motors seem to rated for 16-17v so personally I'd run it. The higher the kv the lower the max voltage and higher the current draw for a given RPM. He's got a ROAR/race spec 540 motor,which are designed and rated to be run off 1s/ 2s , and are not rated for any higher than 8v Here's the spec off the x20 from LRP kV5.200 Application - Advanced4WD TC - 1/12 Application - Expert4WD SC, TX, BX - 2WD SC, BX WindingStar (Multistrand Copper Winding) Voltage input3.7 - 7.4V Magnet materialWorksTeam Sintered (12.5mm #50637) RPM38.480 Weight165g Power414 Application - Most top racer's choice4WD BX Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 17, 2018 Share Posted February 17, 2018 Here's the spec of your trackstar Note: Sensor cable included Specs: Can Size: 540 Turns: 13.5 RPM/v: 3040kv Sensored: Yes (Standard 6 pin harness) Max voltage: 7.4 (2S) Max Current: 36A Max Watts: 255w Can Diameter: 36mm Can Length: 53mm Shaft Size: 3.175mm Weight: 178g Quote Link to comment Share on other sites More sharing options...
Si Coe Posted February 17, 2018 Share Posted February 17, 2018 Yes but you are comparing a 5200kv motor with a 3040kv one. In theory the 3040 on 3s will only be spending spinning at the same RPMS as the 5200 on 2s. There are 3 things that kill motors if you push them too hard: heat, the bearings going and the rotor delaminating. If the rotor and bearings in the 13.5t are the same spec as those fitted to higher kv models in the same range they can take the rpms just fine because they reach them on 2s with those motors. It's really just heat you need to worry about, which is mostly a function of gearing. The manufacturer gives a 2s rating for the entire range because anything less than 10.5t can't do 3s Quote Link to comment Share on other sites More sharing options...
bertberr Posted February 17, 2018 Share Posted February 17, 2018 I have a 13.5 hobbywing quicrun sensored 3650 and that states 2s or 3s. Can't think it would be much different to your sensored 13.5... Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 17, 2018 Share Posted February 17, 2018 (edited) 9 hours ago, Si Coe said: Yes but you are comparing a 5200kv motor with a 3040kv one. I was using them as examples of pro/comp 2s rated motor, but I get your point about the kv rating etc etc I suppose, it's all about the current its pulling when on 3s....,.(an inline watt meter would be handy here) to avoid the heat and thus delamination as you rightly point out..... Maths on this one is saying don't do it! Say it's pulling 30-35 A on 2s that's 222-260watts....which is already at the limit of its capabilities 30-35A draw on 3s is 333-388Watts.... P.s the above is based on base voltages of 7.4v for 2s and 11.1v for 3s, but don't forget a fully charged lipo is roughly 1 volt higher than stated here @300bhp/ton what ESC is it run off? Edited February 17, 2018 by Fly In My Soup Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 17, 2018 Share Posted February 17, 2018 32 minutes ago, bertberr said: have a 13.5 hobbywing quicrun sensored 3650 and that states 2s or 3s. Can't think it would be much different to your sensored 13.5... What's your amp/watt ratings for that motor?? Maybe that's the difference???? Quote Link to comment Share on other sites More sharing options...
Si Coe Posted February 17, 2018 Share Posted February 17, 2018 The power draw for the lrp you listed is 414w so even on 3s the trackstar should be ok. The ESC is admittedly another issue. There are few 1/10th ESCs I'd actually want to use with 3s. Many say they can handle it but prove unreliable in practice. 1 Quote Link to comment Share on other sites More sharing options...
OllieNZ Posted February 18, 2018 Share Posted February 18, 2018 7 hours ago, Fly In My Soup said: I was using them as examples of pro/comp 2s rated motor, but I get your point about the kv rating etc etc I suppose, it's all about the current its pulling when on 3s....,.(an inline watt meter would be handy here) to avoid the heat and thus delamination as you rightly point out..... Maths on this one is saying don't do it! Say it's pulling 30-35 A on 2s that's 222-260watts....which is already at the limit of its capabilities 30-35A draw on 3s is 333-388Watts.... P.s the above is based on base voltages of 7.4v for 2s and 11.1v for 3s, but don't forget a fully charged lipo is roughly 1 volt higher than stated here @300bhp/ton what ESC is it run off? The max motor wattage is a fixed figure.... I=P/V 255w/7.4v=34.5A 255w/11.1v=23A Quote Link to comment Share on other sites More sharing options...
300bhp/ton Posted February 18, 2018 Author Share Posted February 18, 2018 (edited) 10 hours ago, Fly In My Soup said: @300bhp/ton what ESC is it run off? It’s a budget 120A one from eBay. Seems to work well on 2S, I have a couple of them. Edited February 18, 2018 by 300bhp/ton Quote Link to comment Share on other sites More sharing options...
bertberr Posted February 18, 2018 Share Posted February 18, 2018 6 hours ago, OllieNZ said: The max motor wattage is a fixed figure.... I=P/V 255w/7.4v=34.5A 255w/11.1v=23A I've often wondered this... Is wattage a fixed? If that were the case, surely you'd get no speed difference flipping between 2s and 3s? 1 Quote Link to comment Share on other sites More sharing options...
OllieNZ Posted February 18, 2018 Share Posted February 18, 2018 1 hour ago, bertberr said: I've often wondered this... Is wattage a fixed? If that were the case, surely you'd get no speed difference flipping between 2s and 3s? The speed (rpm) of a brushless motor is governed by the input voltage multiplied by the kv rating, so naturally a higher voltage will net you a higher rpm Quote Link to comment Share on other sites More sharing options...
capri-boy Posted February 18, 2018 Share Posted February 18, 2018 8 hours ago, 300bhp/ton said: It’s a budget 120A one from eBay. Seems to work well on 2S, I have a couple of them. These are renowned for having terrible bec's and thus burning the fan out when running 3S. I've run quite a few now, all on 2S. Friends have run 3, with replacement fans, none have lasted long. Check how much contact you've got between the heatsink and fets - I've seen some that are only 'secured' by the action of the case. Quote Link to comment Share on other sites More sharing options...
300bhp/ton Posted February 18, 2018 Author Share Posted February 18, 2018 Will check thanks. The instruction say the fan is rated to 8v and there is a 12v optional fan you are meant to use for 3S. Quote Link to comment Share on other sites More sharing options...
Fly In My Soup Posted February 18, 2018 Share Posted February 18, 2018 (edited) 19 hours ago, OllieNZ said: The max motor wattage is a fixed figure.... I=P/V 255w/7.4v=34.5A 255w/11.1v=23A 12 hours ago, bertberr said: I've often wondered this... Is wattage a fixed? If that were the case, surely you'd get no speed difference flipping between 2s and 3s? I would not use the 255w figures..... Even though your right I worked out 350ish watts, as that's the power output ( Voltage X Amps) based on the possibility of motor amp draw fluctuation upto around 30-35A Anyway... Those (255w) figures are the max found wattage (power) the motor is capable of handling / producing during a static test without overheating at a certain rpm on a certain voltage And as such wont always be a fixed figure, as the motors capabilities alter when given higher voltage, different situations etc So its simply stating that 255watts is the motors max threshold, and should not be used to work out the Ampere rating during usage I'm not knocking your maths Ollie, in fact your maths adheres to watts law perfectly.... Now as Ollie rightly pointed out, watts law states that the amp draw should decrease when fed a higher voltage ( A= W÷V) ......but its not that simple....where not testing static electrical circuits where testing a very fluid entity......amp draw will decrease and increase when in use by a substantial amount... It gets more complex when you factor in that there's input wattage and output wattage.... This would be easy to work out if we had accurate running (under load) data.....for the Amperes drawn in use To accurately define / calculate real world amperage would have to rely on an inline wattmeter being used when driving to record data, this is due to many factors being involved in the equation that will effect amperage drawn by the motor whilst in use........the most common being amp spikes caused by terrain, acceleration/deceleration, stall current spikes, back EMf, gearing etc etc etc Like I say, it would be simple..... If indeed your ESC will be fed roughly 350watts (input wattage) and your motor will draw ?? Amount of amps , let's say Ollie has it right @ 23amps on 11.1v and the motor does draw 23A consistently, that's still 255w , right on the limit of the motors threshold, without factoring in any amp spikes. It would also leave your ESC caps some massive emf to cope with, as you'd have a massive back flow off watts on one side (350ish vs. 255 ish) That make sense to anyone??? P.s. interesting reading, on a help forum https://electronics.stackexchange.com/questions/245518/how-much-can-i-overvolt-a-brushless-motor Best post 1down vote In asking the question, you seem to have assumed the brushed or brushless design of the motor is not important. That is not true. A brushless motor requires an electronic controller. The effect on the motor in that case is as much determined by the controller design as it is by the motor itself. You have another answer that addresses that. For a permanent magnet brushed motor, at the voltage level in question, the effect of doubling the voltage is mostly a question of the effect of doubling the speed. With no load connected to the motor, will probably be ok at twice the rated voltage and twice the rated speed. The current drawn by the motor is primarily determined by the load, not the resistance of the motor. The current is given by I = (V - E) / R, where V is the supply voltage, E is the back EMF (proportional to speed) generated in the motor and R is the winding resistance. If there is no load, E is practically equal to V when the motor is running at full speed. It is only reduced by the slight load due to the friction of the bearings and commutator and the air drag on the moving parts of the motor. If there is a load, doubling the speed may increase the load dramatically thus increasing the current and increasing the power developed in the resistance of the winding. The load will particularly increase dramatically if there is something like a propellor connected to the motor. Even without a load, it is possible that doubling the speed may increase the heating due to internal friction and air drag to the point that the motor fails. In an inexpensive motor, vibration could also be a factor. Edited February 19, 2018 by Fly In My Soup Quote Link to comment Share on other sites More sharing options...
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