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  #21  
Old 17-01-2010
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Um, surely that depends on the motor used?
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  #22  
Old 19-02-2010
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  #23  
Old 16-03-2010
ianjoyner ianjoyner is offline
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Okay so in helping me understands the trade offs between different setups:

Take the truggy 4 cell starting point. Why not just get the 2000kv and gear up if you want to go faster or gear down if you want more torque. What is the advantages of going up to the 2250kv or down to the 1700kv? Assuming you want more or less speed respectively. Thanks.
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  #24  
Old 16-03-2010
chris_dono chris_dono is offline
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brushless motors have a "range" of gearing that will work.. too far outside either of these and you'll just get the motor too hot (and eventually smoke it)
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  #25  
Old 16-03-2010
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Quote:
Originally Posted by ianjoyner View Post
Okay so in helping me understands the trade offs between different setups:

Take the truggy 4 cell starting point. Why not just get the 2000kv and gear up if you want to go faster or gear down if you want more torque. What is the advantages of going up to the 2250kv or down to the 1700kv? Assuming you want more or less speed respectively. Thanks.

It took me a bit to get my head round this, it really is a battery/motor combo with a sweet spot of around 30,000rpm

With my limited understanding of it all now this is how I see it.

Higher the voltage (ie cell count of the battery) the more efficient the system will be giving longer run times and cooler temps.
So if you go for a 6S (6 cells = 22.2volts) battery you need to match that to the right kv motor.
Motor kv x voltage = RPM's so to get 30,000 from 6S you need a 1400kv motor.. Simply going up and down motor kv's with the same batterys will put you above and below the efficeint range of the motor

Truggys also require a larger sized motor (longer usualy).

Another thing I didnt really twig for a bit was a larger battery cell count does not equal more weight its down to the mah rating. A 6S 2500mah lipo is approx half (dont pick me up) the weight of a 3S 5000mah lipo


Hope that helps
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  #26  
Old 16-03-2010
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Sam, a 6S 2500mAh pack would be the same weight as a 3S 5000mAh pack - look at the power of the battery - 22.2x2.5 = 55.5Wh, 11.1x5 = 55.5Wh. What affects the weight of the battery (essentially) is this power rating.

Basically, it is as Chris_Dono and Sam (BRS) have said, it's to do with efficiency. 2000KV geared up will do all the things that 2200KV will do, but will take a little more power to do so. Therefore, the overall efficiency is lower.

Gearing up/down is of course the cheapest way of doing things, and with the big motors, they're not particularly fussy, unlike 1/10th motors, so the differences aren't that much.

The ultimate efficiency run is to go as high voltage as possible, retaining the same total power. This is why the national grid is at such high voltage - the current is met with resistance, causing heat build up. That heat build up is where electrical energy is transferred into heat energy - thus less efficiency, as energy is lost from the intended purpose. The higher voltage you have, the less current you have for the same power output, and therefore, the higher efficiency you have.

Gearing a motor up draws more current, whilst when using a higher KV to do the same thing, the amount of additional current required is lower.
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  #27  
Old 16-03-2010
ianjoyner ianjoyner is offline
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Thanks all that's pretty well what I was thinking.
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  #28  
Old 17-03-2010
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Quote:
Originally Posted by Marvin View Post
Sam, a 6S 2500mAh pack would be the same weight as a 3S 5000mAh pack - look at the power of the battery - 22.2x2.5 = 55.5Wh, 11.1x5 = 55.5Wh. What affects the weight of the battery (essentially) is this power rating.

Ah now I really get to the bottom of it cheers marv
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  #29  
Old 12-04-2010
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Default A little help?

What I have resting on my workbench at the moment:

1 x Hobao Hyper 9E
2 x Hyperion G3 VX - 4S 6500mAh (35C)


So, gurus - if I get this chart correct, this will be a pretty good setup for my local track:

1 x Tekin RX8
1 x T8 1900 KV


Any idea of what kind of runtime I can expect with this setup?
(Provided I'm not a complete nutter on the throttle.)
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  #30  
Old 12-04-2010
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20-25 minutes given its a 6500mah battery.
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  #31  
Old 13-04-2010
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Yep Jan is right 20-25 hard racing. That motor/esc set is what most of us 4cell tekin guys are running here in the states. If you take it really easy you could make over 30minutes with that huge battery (@ about 200mah/min).
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  #32  
Old 13-04-2010
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Thanks guys! That means one battery change for clubraces on my local track. We have a fairly fast and long track. Finals are 30 minutes. Would be insanely cool to manage one full 30 minute final with no pitstop though. Our best tuners do 2 stops on nitro.

What's the deal with the rotor on the T8? I see mentioning of green locktite. What goes wrong, and how is it fixed with locktite? Should I be worried about the quality of the Tekin cans?
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  #33  
Old 13-04-2010
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...also, any tips on the pinion sizes I should have in my bag'o'tricks, to cater for normal tracks? Ref my previous posts with setup. I believe the "stock" pinion on the Hyper 9E is 14. As these mod 1 pinions are a bit on the steep side, I'd rather not buy 15 different sizes just in case.
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  #34  
Old 13-04-2010
jasonwipf jasonwipf is offline
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Tekin cans are fine the rotors have a glue that can brake loose and the rotor will spin on the inner shaft. Doesnt happen very often as tekin has fixed the major problem but still happens occasionally especially if your rough with the motor or let it get very hot and the resins integrity is compromised at hot temps.

Ya that would be very cool if you didnt have to pit. Higher pinion gear on a big track and very very carful throttle (no excessive wheel spin) management and a large pack might put you over the top though.

But if you do have to change batteries you should be able to get it down to 15-25seconds. If longer your pit guy needs practice or there is something wrong with your set up that makes it hard to change battery.
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  #35  
Old 14-04-2010
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Alright, I've gone and done it. Sold my Novak HV Pro setup, and placed the final order for Tekin ESC/motor yesterday. Setup as of one week from now:

Hobao Hyper 9E
Tekin RX8
Tekin T8 1900 KV
2x Hyperion G3 VX - 4S 6500mAh
Futaba BLS351

I'll let everyone know how the Tekin bits performs compared to the Novak HV Pro setup. Hope to see the 1:8th E class grow into an actual raceclass soon.
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  #36  
Old 14-04-2010
Malcnz Malcnz is offline
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Quote:
Originally Posted by spiro View Post
Alright, I've gone and done it. Sold my Novak HV Pro setup, and placed the final order for Tekin ESC/motor yesterday. Setup as of one week from now:

Hobao Hyper 9E
Tekin RX8
Tekin T8 1900 KV
2x Hyperion G3 VX - 4S 6500mAh
Futaba BLS351

I'll let everyone know how the Tekin bits performs compared to the Novak HV Pro setup. Hope to see the 1:8th E class grow into an actual raceclass soon.
Good luck wih youre Tekin..I just got a 1350KV Truggy one from AMain and mine did the spinning rotor trick I thought also it had been solved but looks like some old stock but Tekin sending me a new rotor so hopefully all will be good...must have been a friday afternoon build this motor as it was also missing the sensor wire which was hopefully also sent by Tekin last week but havent got it yet and lucky I had one to use..thought I was buying the best when buying Tekin
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  #37  
Old 15-04-2010
jasonwipf jasonwipf is offline
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use green thread lock and let it cure for 24hrs that should bond the rotor back on. I did that fix and ran a 4hr enduro the next week with the same motor and no problems. Heck I put green thread lock on even new tekin rotors now just as a preventative measure when I red or blue thread lock ALL the endbell (front and back) screws on all my tekin or castle motors.

I run the 1900 too in my main racer buggy, and it is smooth. I recently bought the castle 1800 and it runs as fast but you have to go up a tooth on your pinion to compensate for the lack of rpm. torque wise its fine. But it does get hotter than my tekin and you can feel some cogging on the low end. Since it is sensorless too once in a blue moon on a dead start the motor will stall upon giving it gas and I have to pump the throttle once or twice to get it moving (happened 2-3 times during my 1st 140minutes of testing)

Malcnz, you are buying the best in performance with tekin. But they are new and have a reliability bug or 2, luckily they will replace any faulty equipment at a drop of a hat. Their service department is committed to the consumer! I'd rate tekin and castle as such:

Tekin
Performance A+ (great motor KV combos, run cool and smooth)
Reliability B (rotor issue and rare ESC problems)

Castle
Performance A- (run hotter than tekin, KV tad too high or a tad too low)
Reliability A (only 3 screws on front endbell, can and do come loose more often than tekin and result in the can sliding off or busted front bearing, otherwise it would be a solid A+, red thread lock it and its not an issue)

Neu motors are also good. The rest of the stuff on the market I wouldn't touch. Your fine with either Tekin or Castle.
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  #38  
Old 15-04-2010
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Good stuff J! Thanks for the info.
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  #39  
Old 15-04-2010
jasonwipf jasonwipf is offline
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Quote:
Originally Posted by spiro View Post
Alright, I've gone and done it. Sold my Novak HV Pro setup, and placed the final order for Tekin ESC/motor yesterday. Setup as of one week from now:

Hobao Hyper 9E
Tekin RX8
Tekin T8 1900 KV
2x Hyperion G3 VX - 4S 6500mAh
Futaba BLS351

I'll let everyone know how the Tekin bits performs compared to the Novak HV Pro setup. Hope to see the 1:8th E class grow into an actual raceclass soon.
Ya Novak HV 6.5 was my first system and while it was fast I burned out 1 motor and 3 ESCs. Fans had to be on all the time or it was toast where I live (hot).

Hyper 9Es rock, you should like that combo you listed there. Your lipo packs are bit huge but heck you'll last a long time. With that much weight and if especially if you are hard on the throttle you do risk spinning a rotor with tekin. I run lighter 3700mah packs and I green threadlock or super glue my tekin rotors when they are new and I dont have any problems. In your case do that too when you get your tekin. green threadlock or (very fine) super glue your rotor by letting it seep into any cracks around the magnet and the main axle of the rotor. Dont get any on the bushings or ends that slip into bearings. then red (small amounts) or blue thread lock all the endbell screws just to be safe.

Motors do run cooler when you use lighter packs or smaller pinions. With that big of a pack watch your temps and consider running smaller pinions to ease the load and bring temps down. Tekin does run cooler than most. I run between 13-17T and 120-150deg F motor and 2-3 lights on my RX8 (125-140deg F) depending on the track. You dont want to run more than 5 lights on your RX8 (onboard heat indicator) and/or 170F on your motor*, 200deg F motor limit is wrong.

*motors can be 50Deg F hotter at the core of the rotor than they are on the outside of the can so a 170degF temp gun reading on the outside can be 220Deg F in the middle of the rotor which is thermal breakdown temperatures for glues and resins both on the rotor and in the windings of the can. A 200deg F motor on the outside could be 250deg F in the inside! Way over heated. You risk spinning your rotor, demagnetizing it, damaging your can or any electronics on the small motherboard inside these motors that control sensored activity, on ANY brand of motor.

Dont mean to spoof you there spiro, but I want you to run without incident and learn off my mistakes.
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  #40  
Old 15-04-2010
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Again, great stuff! You got me a bit worried on my batteries there, but I'll give them a go.
(Wish I had checked the weight issue with you lot before ordering them though. )

Didn't know about the onboard templight feature. Pretty nifty!

Now, how to speed up the snailguys from USPS?
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