2200kv MMM
 

Hi Everyone,

I have a Losi 8Te 2.0 and just converted to brushless and i love it!!!!
My club runs 20 minute mains and i am reaching 3.0v LVC at 17 mins, everything is turned right down on the ESC.

Battery is a HYPERION G3 VX-35C 6500-4CELL LIPO
Gearing is 13/45 ATM - The track is quite short with not alot of WOT.

Would a 5cell of the same capacity last longer?

Regards

gear your truck down so that you use full throttle.. more efficiency at WOT.

With 5s your going to need to gear down regardless to make up for the extra rpm

More voltage + lower gearing = higher efficiency (longer run-times).

Do you really think 5s is needed? 4s should be PLENTY on a short track.

that's my philosophy.
i run 6s through my revo with only 40mph gearing and i'm pushing 30+ mins of race pace :yipi:

Thanks,

Starting to understand a bit more now!

I will see what the runtime is like with a 12t pinion

Hum, keep in mind that higher voltage means higher RPM so higher losses in the motor bearings.
But for heavy trucks like truggys or MT, with the 2200kV, 5S with small gearing is the way to go, maybe on 6S the motor loses a lot of efficiency in the bearing...
A 1520 1Y on 6S should give you better efficiency anyway... :yipi:
Brushlessboy, I would have a question : The efficiency at full throttle is best for the motor or ESC ? Or both ?

I don't think you are grasping the whole point, or understanding what we are talking about...

When you go UP in voltage, you also go DOWN in gearing, resulting in the exact same RPM & Top-Speed as before...just with higher voltage.

So, going with higher voltage does NOT mean higher RPM since you are going with lower gearing at the same time. RPM remains the same with higher voltage and lower gearing, but the efficiency and run-time greatly increases.

No kidding :lol:
Read again what I wrote, I talked about MOTOR RPM, not transmission RPM :whistle:

I just realized that we are talking about the same thing, just in two different ways...my bad.

I just realized that we are talking about the same thing, just in two different ways...my bad.

if you are at half throttle the fets must turn on and off a lot to "limit" the voltage in laymans terms.

but at WOT the fets only need to shunt power to the 3 phases and that's it, no more in-between-phase-switching. :wink:

Hi I'm running a 2200kv 1515 1Y motor in my converted lightning stadium pro, 14t pinion 5800 4s lipos with lvc at 3.2 the finals where i race are 15 minutes and unless i nurse the car i hit the lvc at 14mins. I'm only touching WOT for a split second on the main straight, would gearing lower help (i ran a 15 tooth 1st time out and hit the lvc at 14mins 30 seconds but had a 4 lap lead)
punch is 75%
timing 0
start power low.

would a 1800kv 1512 1.5Y be man enough for a truggy as i have the chance of getting one for a good price and would this give me 15 mins at full race pace(with the same 4s lipos). (tbh its won every time i've used it but i would like to be able to run at the same pace as the heats in the final)

cheers

Darren

Why not run the 1518 1800kv? I run this in my 8ight-Te. Plenty of power and runtimes are great! I can practice with a 5000mah with my LVC set at 3.3v for 18-20minutes of track time. Motor temps at about 120F at max. Everything else is below 100F

No. A 1512 1.5Y will short your runtimes if geared for the same speed, because it won't be efficient at all in a truggy. The motor is too short. The runtimes don't depend of your motor, unless its undersized, but of your voltage, your gearing and the weight of vehicle.
To increase runtime you need to increase efficiency, if you cant change your motor, you need to up you voltage and reduce the gearing, to keep the same power and reduce current.
More over your timing is not right for Y windings. Best efficiency with the 2200kV 1515 1Y motor is 4-5, not 0.

==>Try first to reduce a little your pinion, set the correct timing. Punch at 75% is good, you don't need more power at start.

A Castle 1518 1800kV will be more efficient in a truggy on 4 or 5S, and the 1520 1Y 1600kV on 6S with low gearing would be the best solution ever to have insane runtimes, but I do not know if the rules permit theses motors...

many thanks for the super quick replys, i only thought about a 1512 1.5Y as i have the chance of getting one cheap, a 1518 1800kV would be my prefered choice but funds will not stretch to one at the mo (if the £-$ improves i may be able to stretch to one ). I've set the timing to 5 and will try a 13t pinion (I dont think i can fit anything smaller)
what has suprised me the most is that i seem to get better run times when its muddy and less when its dry and dusty????

Depend of you style of driving. Cool driving style will be longer on mud for example, hard driving style will be longer on dust and dry floor.

I'm still very much learning and trying to drive tight lines without needing help from marshalls, at my last race i managed a 15 minute final without crashing once, i had the fastest lap and won by 6 laps :-) but the fast guys were not there last time :-(


on a slightly different note do you think lipo technology will inprove so we have 7000+mah in the same size and weight as 5000 now? as that would solve a lot of problems.

This isn't necessarily true and could be misinterpreted. A 1512 very well could be more efficient in a truggy with the right conditions and the right driver. A smaller motor will very likely achieve more runtime in ideal conditions as well(as long as it isn't too small) - it simply takes less power to move itself. I am not saying the 1512 is the answer, but i wouldn't flat out say that it isn't, either. Likewise, the 1518 may very well achieve less runtime on the same 4s battery in this application.

5s on the 2200Kv motor is quite aggressive as well - I am not convinced that this is as efficient as 4s in this particular application to be honest. I don't know if you could achieve a low enough gearing for starters, so current draw very well could increase rather than decrease. I doubt it is as drivable, either. Zero timing will be the most efficient with pretty much any of these motors, but you won't likely find more than a few seconds of runtime when switching from zero to 5 degrees anyways. Higher timing will hurt efficiency more at low speed, which is where most of the time is spent in RC racing - timing advance reduced torque and increases rpms. You torque to accelerate a truggy, so zero timing gets my vote.

My suggestion would be to simply gear down a tooth and set the LVC to 3.1 or 3.0 volts/cell to gain the runtime if you are using good batteries. And stick with Zero timing.

According to Patrick the best efficiency for Y Windings Castle motor is 2-4...:no:
A 1512 motor is clearly undersized for a truggy under race conditions, I experienced myself higher runtimes with 1515 than a 1512 in a buggy, so imagine in a truggy...
When the motor is too short, it eats a lot of amps because of its low ratio torque/amps.
5S with increased punch control and gearing for same speed than 4S won't draw more amp than a 4S configuration IMO...

It isn't black and white 2-4 degrees, though. Here is the rest of what Patrick stated regarding timing - "Timing of about 2-4 will work best with the four pole Neu or Neu/Castle motors. They will accept more timing, but will run a bit hotter.

Well, I wish I could tell you exactly, but it changes based on load, RPM, and voltage. High RPM setups (6S, low load) will get maximum efficiency with a little more timing, low RPM setups will get maximum efficiency with a little less timing"

If you read into this a little deeper, you may draw from it that higher timing would be beneficial in high voltage oval racing, for example, where the motor will spend considerable time making "high rpms" with fairly low load - a track racing application would benefit from lower timing(lower than 2-4 degrees would be zero), as most of the time is spent in a much lower rpm range(and higher load from constant acceleration). I already mentioned that I doubt there would be a considerable difference with 0 or 5 degrees timing in reality, but when you are cutting it close for runtime, every bit counts. :) As a side note, when a motor's timing is advanced in one direction, it is effectively retarded when reversed(brakes). Motor braking with higher timing would theoretically decrease efficiency in this scenario(retarded timing decreases efficiency, torque - this would definately be the case with a sensor based ESC and mechanical motor timing, though may not apply here - depends on ESC).

I am not sure the 2200Kv motor can be geared for the same speed on 5s in this application, so the potential for higher current consumption is present(would need a 10t or 11t pinion, which may interfere with the diff drive cups or not be compatible with the motor mount). Also, it is not "clear" that a 1512 is undersized in a truggy. It depends, just like timing, on various factors. Someone on this site has reported excellent results with the Tekin 1400Kv buggy setup in an XT8 truggy for example - the 1400Kv Tekin buggy motor is essentially a sensored 1512 motor. A 1512 motor can make plenty or torque for a truggy. Perhaps not for you personally, but you may drive differently than others, and may have other factors as well. If you are trying to reach 50+mph in a 10+ pound truggy, then a larger motor is likely the better solution, but for an average sized track and 35mph speed with a sub 10 pound truggy, a 1512 that is geared, volted and selected appropriately can be a better option for overall performance - including runtime. It could also overheat in the hands of an erratic driver with lower quality cells and a poor setup(as could a 1515, 1518 or any other motor for that matter). Bigger isn't always better - especially when you are trying to achieve maximum runtime. A 1512 will naturally draw less current than a 1515 of the same Kv to a certain load.
:yes:

At then end of the day, I still suggest that this user first tries to drop down 1 tooth on the motor pinion, lower the LVC threshhold to 3.1 or 3.0 volts/cell(I use 3v/cell personally) and use zero timing for optimum runtime results. I also prefer to NOT use punch control, as I find it makes the throttle feel "muddy" - I prefer using the throttle curve or throttle EPA adjustments to tune the throttle to my trigger inputs. This is based on my experience racing brushless vehicles for the last 10 or so years. :)

Like nuz69 says, if your track's rules allow it, volt up and gear down. Higher voltage is more efficient, so it will get you longer runtimes. Just use the calculator to determine what gearing you need to run your current top-speed, but on the increased voltage.

You can also run a higher discharge (higher "C") LiPo to get more runtime. For instance; If you are currently running a 30C 4S 5000mAh LiPo, it produces 150A. If you upgraded to a 40C 4S 5000mAh LiPo, it would produce 200A, which would give you longer runtimes.

Ok, thanks Mike for this explanation, it will help many people to understand timing issues ^^
But here in Europe, racing = geared for 43-45 mph and a 1512 just can't run "cool" in a truggy in this condition, no matter the smoothness of the driver finger... Many people encountered heat issues with the small tekin motor in buggies with theses speed and they use now the truggy version of the motor in their buggy. Sometimes they still have heat issues :neutral:.
Maybe in USA where the track are relatively short compared to ours, you can use a 1512 in a truggy or buggy geared for 35 mph, but in the European, the tracks countains massive hard turns with long straight line which requires high gearing, and we just can't use small 1512 motor, mean temp for drivers go over 180F wen its 70 outside :(, and the vehicle is a buggy ...
Many people use then neu 1515 or equivalent Castle, but manage to run them at 140-160 F in buggies. I know someone who run a 1518 in a light hyper 9e and his runtime is better than with his 1515...
Geared for 35 mph, i would say "maybe" it can increase runtime.
But for more than 42 mph, I have serious doubt.
Scooterboy, what is the temp of your motor at the end of one run ?

Chad,
A higher discharge capable battery would only yield more runtime if the current pack is being pushed excessively. Mah is Mah, after all. What you said "can be" true, but isn't necessarily true.

Nuz,
I am not suggesting a 1512 in this case, and in fact use a 1515 sized motor in my truggy and have also used the same size in a buggy. For truggies, the larger motor is "usually" the better option, but my point was that motor size alone doesn't determine efficiency. A proper 1512 motor in some conditions is sufficient and even ideal. There are simply many factors that can add up - including the actual driving/track conditions and the driver. For example, I have a buddy here with a D8 buggy and D8 truggy - he had truggy motors in both and runs 5s on both vehicles. He often overheated his buggy but not his truggy. Going from a 1700Kv truggy motor to a 1900Kv buggy motor yielded cooler temps in the buggy(geared for the same speed) - the smaller motor was more ideally suited to this particular application in terms of acceleration, deceleration/braking, load and driver style. The smaller motor simply works better. It isn't "necessarily" about motor size and size doesn't determine efficiency.
As far as US tracks vs European tracks - I can't comment on this aside from speculation, as I have never been to Europe. I will say that my local track has a 220 foot straight and even geared for 36mph in my truggy, the nitros aren't any faster. I actually can make faster, more consistent laps when geared for 35-37mph than I can when geared for low 40mph range. The 1/10 second on the straight that the extra speed may yield is lost in the turns and technical sections where I need the resolution more than raw power or speed. I also get lower temps and longer runtime when I gear down and gear even lower on long mains if needed. Just because RCCA or RCDriver clocked a nitro truggy at 39mph doesn't mean they actually go this fast on a track in a race - maybe on a large oval track, but in an off road dirt track, average speeds are typically less than 15-20mph and peak speed is seldom as high as 40mph.

I've not checked temps but you can touch / hold the motor no prob after a 15 minute final, I'll see if i can borrow a temp gun next time. according to the advanced calculator a 14t pinion with the 2200kv motor should give me a max speed of 35mph and require 6000mah for 15 mins. Tbh I cannot use WOT (the track i race at is fairly small with a good lap being around 20 to 30 seconds depending on the layout they are using, the straight is short and very bumpy (http://www.plymouthrc.co.uk/))

LOL @ Mike... size doesn't matter, lol. But that is at least correct for motors, I run a 1509 in my Ve8 for indoor track, temps and run time are great. My truggy has a 1515 now, and I ordered a 1512 for it, although it got TQ in first race so I will leave it alone for now.