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the brushless vs brushed debate

the brushless vs brushed debate

Old 05-28-2007, 08:47 AM
  #61  
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Originally Posted by kĢv!n
Do brushless motors still get warm/hot like brushed motors do? I understand its all down to gearing but brushed motors still get warm when they are geared properly!

Kev
No
it`s the brushless speedo's that get hot & go up ,not the motor

things are moving very fast in devolpement,
IE;;novaks new spectrum speedo ,so to have even faster switching ,with less heat

it's a shame really but new things will hve teething probs for quite a while till WE know what to do & not to do

only thing i don't like with brushless is the ammount of company's relabling other speedo's & BL motors ,thus making it look like there are loads of makes out there to get the reliability sorted quicker
there isn't
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Old 05-28-2007, 08:48 AM
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As Toughbeard wrote somewhere else on the threads, as the borg says " Resistance is Futile"
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Old 05-28-2007, 09:02 AM
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Originally Posted by SlowerOne
TerryS - the reason no one uses rare-earth brushed is because until this year it was against the rules!
Yes true. If the rules have changed then I guess people will run rare-earth brushed if they choose to, the same as they will run brushless if they choose to. Doing tech inspections on rare-earth vs normal magnets in brushed may not be easy the same as tech inspections for brushless may not be easy.. but ultimately anything can be checked, it just may not be quite so easy.

Brushless vs brushed, I think we can safely say..
Brushless won't go away and brushed won't die completely!
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Old 05-28-2007, 09:21 AM
  #64  
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Err as far as I know rare earth are still not allowed on any brushed motor, at least in the UK.
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Old 05-28-2007, 09:34 AM
  #65  
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I don't mind running brushless but my hope is the rules are more open so many manufactures can run instead of having to run products that not all care for. I don't like being forced to run one brand just to race.
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Old 05-28-2007, 10:01 AM
  #66  
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Originally Posted by Terry_S
I doubt you could connect it reverse, that would damage any ESC. It could have protection built in to prevent a 'self destruct' scenario but there WOULD be something go wrong. (it's possible to reverse protect a brushed speedo BUT it would need more MOSFETs, be a bigger size and cost more!)
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That really worked on that old big G12 and G9 ESC. They had a high current schottky integrated and together with the FETs this caused a shortcircuit on the reversed battery and an integrated 100A fuse or outboard solderconnection (depending on revision of the ESC) then popped immediately saving the ESC. But this were the only ESC I ever found using that reverseprotection. I think todays small SMD FETs wouldnīt survive this.
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Old 05-28-2007, 10:15 AM
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Hi V12, yes you're right it's possible to have protection but the integrated fuse still popped and has to be repaired. Like you say todays SMD FET's won't so easily survive a reverse polarity connection.
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Old 05-28-2007, 10:18 AM
  #68  
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Regarding the rare-earth magnets this doesnīt make sense at all as those motors would be much more expensive. This is even more senseless with stock motors. Also here in Germany rare-earth magnets at brushed motors are still against the rules as itīs in the UK.
But even using those magnets a brushed motor never will be as efficient as a brushless one, you still have that brush/commutator what will limit efficiency.
For stockmotors brushed still is not bad in my opinion, especially as long as you run those HP longwear LRP,GM or CS brushes also brushed systems seems just more easy to setup. But for modified brushless will be the future even when there is still enough room for developments.
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Old 05-28-2007, 10:31 AM
  #69  
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Terry, repairing wasnīt the problem as the fuse was located from the outside but this special small fuse was expensive and did limit a little the braking power. The later used solderconnection also was on the outside of case and just could be repaired but even Tekin isnīt using this anymore.
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Old 05-28-2007, 10:37 AM
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solder fuse is still on the g-11's from tekin... And yes they work..
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Old 05-28-2007, 10:51 AM
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Originally Posted by V12
Terry, repairing wasnīt the problem as the fuse was located from the outside but this special small fuse was expensive and did limit a little the braking power. The later used solderconnection also was on the outside of case and just could be repaired but even Tekin isnīt using this anymore.
Tekin wont make anymore solder fused ones because it probably put them out of bussiness in teh first place

No blown ESC no replacements. Try reverse connecting a VFS1 and watch you 190USD taking the fast lane to hell
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Old 05-28-2007, 10:51 AM
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Originally Posted by V12
Regarding the rare-earth magnets this doesnīt make sense at all as those motors would be much more expensive. This is even more senseless with stock motors. Also here in Germany rare-earth magnets at brushed motors are still against the rules as itīs in the UK.
But even using those magnets a brushed motor never will be as efficient as a brushless one, you still have that brush/commutator what will limit efficiency.
For stockmotors brushed still is not bad in my opinion, especially as long as you run those HP longwear LRP,GM or CS brushes also brushed systems seems just more easy to setup. But for modified brushless will be the future even when there is still enough room for developments.
Why is everyone claiming that brushless is more efficient blah blah blah... Yes the principle of a brushless motor is more efficient than a brushed. HOWEVER, it vastly depends on the design and also on the efficiency of the controler !

I mean, look at the actual brushless speedos, they all require massive heat sinks and/or fans to cool them down. Isn't THIS a proof of bad efficiency ? Energy is mostly lost in HEAT. Also the motors get as hot as brushed motors, their actual design is far from efficient. Have also heard from a top driver that the actual brushless motors were very inefficient at top speed. Not to mention the fact that we have to get as low as 3.5T, and the lower the wind, the lower the efficiency in both the motor and speedo.

Now from what i gathered a brushed with rare earth magnets you wouldn't need to go to such low turns, probably a 10T would be the fastest thing we'd be able to drive. They provide enormous torque and revv less than if ceramic magnets are used, so less commutation and less sparkling, better efficiency. Rare earth brushed run cool, much cooler than with ceramic as there are no driving efficiencies in the speedo.

I guess my point is, bring on the rare earth brushed motors and let the users decide. After all at the moment brushed are at a disadvantage from being restricted to ceramic magnets.
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Old 05-28-2007, 11:15 AM
  #73  
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Originally Posted by SlowerOne
...No, brushed cannot ever be as efficient as brushless - simple physics. However, a brushless can never be as easy to tech as a brushed. Rare-earth magnet 19T and 27T motors are THE future for the Stock classes. Brushless are too easy to tamper with, and too difficult to check, for the National races. Clubs and locals will allow the 19T and 27T equivalents, but it won't be long before they give up when the cost of buying the latest one pales, or people find out how to, ahem... 'tune' them!!...
Teching brushless motors is neither difficult nor complicated. TeamNovak has posted teching instructions on their website for a couple of years. The chart has recently been updated with instructions for teching motors with the rotors removed.

Motor Inductance: How to Check for Compliance

I believe that clubs and locals will be the individuals most eager to adopt the BL technology because of the lower ongoing costs and the decrease in maintenance. Racers will be less eager to "cheat" when they realize that their motors can be teched for compliance. Locals are the ones who want BL spec racing to work and level the playing field so that members can enjoy competing again without the "motor of the week" issue.
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Old 05-28-2007, 11:41 AM
  #74  
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If rare earth magnets perform faster , then we would of sean um running on brush motor`s by now.. ....
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Old 05-28-2007, 12:15 PM
  #75  
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Originally Posted by TRF415boy
Why is everyone claiming that brushless is more efficient blah blah blah... Yes the principle of a brushless motor is more efficient than a brushed. HOWEVER, it vastly depends on the design and also on the efficiency of the controler !

I mean, look at the actual brushless speedos, they all require massive heat sinks and/or fans to cool them down. Isn't THIS a proof of bad efficiency ? Energy is mostly lost in HEAT. Also the motors get as hot as brushed motors, their actual design is far from efficient. Have also heard from a top driver that the actual brushless motors were very inefficient at top speed. Not to mention the fact that we have to get as low as 3.5T, and the lower the wind, the lower the efficiency in both the motor and speedo.

Now from what i gathered a brushed with rare earth magnets you wouldn't need to go to such low turns, probably a 10T would be the fastest thing we'd be able to drive. They provide enormous torque and revv less than if ceramic magnets are used, so less commutation and less sparkling, better efficiency. Rare earth brushed run cool, much cooler than with ceramic as there are no driving efficiencies in the speedo.

I guess my point is, bring on the rare earth brushed motors and let the users decide. After all at the moment brushed are at a disadvantage from being restricted to ceramic magnets.
Your right regarding design you could do a lot of improvements with brushed motors but the same is true with brushless. If you look what the guys from the racing boat scene are doing on their motordesigns our motors are just small toys. You have to say they are using higher voltages what change a lot but I donīt think anyone wants spending such sums. They have had the rare earth motors with more pols and other things and look what they are using now.......brushless. The other side is there are rulebooks what specify the design of motors and I donīt think rules will change a lot if any. Why should anyone design better motors when these are illegal afterwards?

Regarding the speedos you have to say how a brushless unit is working. As the BL motors are three-phase there are much more Power-FETs involved in compare to a brushed speedo what uses one phase. Another thing is a brushed speedo will not switch at full throttle so there are just the onresistance of the FETs producing powerlosses/heat. A brushless speedo needs switching all the time even on full throttle so there are always additional switching losses producing heat. This is with all brushless speedos and canīt be changed. So you canīt compare brushless and brushed spedos in this area, but maybe sometime there will be better speedos than today. But even now some speedos run hotter/cooler than others.

Regarding motors there are currently changes in design as the rules allow now sintered rotors which run cooler than bonded.
On the high torque low rev motors you can do this also with brushless, some company offer different rotors for this purpose but from what I hear most people do prefere the lower torque motors.

I think noone really need 3,5T motors, leave the factory drivers and their level aside. Most drivers beside these talented guys even canīt control those motors. But even a 5,5 or 6T BL motor will produce about 100W more power than any brushed motor will do. Alone this fact will force motor and speedo running hotter, especially when braking. And donīt tell me rare earth motors will be better here, rules will never change allowing them, I bet on that.
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