niznai

Tha was my first thought (the sampling rate of the sentry). But again, that is not the case. My Sentry is adjusted to sample every .1 second indeed. But that doesn't have any implication regarding the RPM (which is a continuous function as it is what the motor does and the motor does not stop dead inbetween pulses) nor in the current (which is a pulse but with a much higher frequency, I think about 4kHz). That means in a .1s there are 400pulses and these last say 1/4000s each, so if a reading is taken at a higher speed (say the reading lasts 1/10000s) it is possible to measure a trough. But then you would see these dips all over the place, but not associated with dips in RPM.

If the reading lasts more than 1/4000s, then during the reading there would be at least one pulse read and the value integrated over the entire reading time would be somewhere between zero and max, whatever. Again, such events should occur over the entire duration of the log and should be statistically evenly distributed, and again no RPM dip should be associated. That is again not the case.

Moreover, you can see the drop is progressive and can be followed in a number of successive readings (samples), both in RPM and current before the graph climbs up again, so it's not just an errant sample taken at an unfortunate moment.

The logic of this phenomenon to me is rather clear. There is a drop in current which is the casue of the RPM drop. Now the question is what is causing the current drop?
A misreading of radio signal?
A software quirk?
An electric event (like battery voltage drop)?
An electornic hardware shortcoming (be it componentry or circuit design)?

Not sure.

For experiment's sake, I will test with a lower sampling rate. My guess is it's not that. I am sure however, if the sampling rate is low enough, the dips will disappear just becasue of the reason I explained above in the comment regarding the difference between driving frequency and sampling rate (frequency).

I pondered the question of load, but as I said above, the drops do not happen on the highest current draw which is at the start when moving away from a standstill. They happen when the car is in motion and accelerating whilst the throttle is maxed out already.

One more comment here. A number of us have run tekin systems at a race on a large track where they noticed motor fade (7 minutes race on a large open track) to such extent that everybody was obviously slowing down. Batteries were checked and they were still going strong (no dumping). Related this to what theisgroup has noticed about the drops coming later when boost ramp was lower, I am curious if there is something going on in the motor/electronics which start to fail as they heat up. In my tests above, the effect appears immediately after start, so it would appear that this is not a good explanation, but who knows? The more we pick at it the more likely we will iron it out.

Skiddins

In a word no.

If your wires are coming unsoldered you need to find someone who can do a better job using a decent soldering station.
Could also try using high temperature solder as well.

Skiddins

Numburn

iTrader: (11)

I got a Tekin RS installed in my TC5 sedan last night and I'm going to pick up an X12 motor before the race tonight. I won't have a whole lot of setup time before the race so I was wondering if anyone would help with some start settings and gearing.

The track is indoor carpet (80x35 maybe). The layout is different, but here's the track:


Thanks for the help!

Markiempje

2nd guess, where is the RPM measured? because you always have some buildup of stresses in the drivetrain before they begin to transmit power. if your sensor is placed on your motor or maybe spur gear it would make sense. the motor builds up speed and RPM and then travels play and tensions the belts. it then bounces back and the RPM drops fast, after that the motor will put power to the wheels.

theisgroup

iTrader: (10)

i don't think the problem is actually load per say, but transition from low load to high load.

i agree that your sensor wire is constant, but the samples are not. and you will grab data that is anomalis. you can see that in your data. I have yet to see a log that does not have a 90k+ rpm sample. My suggestions is that the current draw that you are missing happens at such a quick rate, in the miliseconds range, that the sentry would never capture it.and that you actually see the spike in rpm thanks to the cap on the speedo and the dip is because the cap has dissapated it's reserve

rx7ttlm

iTrader: (30)

need to know the wind of the motor bro.. lol

Numburn

iTrader: (11)

I knew I was leaving something out. 17.5

Cain

iTrader: (294)

with the Tekin RS ESC, how much gearing difference are you seeing with a Speed Passion V3.0 versus a similar wind Novak Ballistic or Tekin Redline motor?

mikky32

I don't now how much but the Speedpassion must be geared heavier.
The Tekin goes faster when you gear lighter and the V3 goes faster with a heavier gearing.

theisgroup

iTrader: (10)

readings are taken off the sensor wire

Cain

iTrader: (294)

Thanks for the info. This would be a 17.5 motor.

mikky32

Just play with the gearing. Go with the Tekin lighter and with the V3 heavier.
V3 with 5 timing and a 13,5 is around the 5,5

goBezerk

iTrader: (10)

OK, just my 2 cents...I don't have a data logger yet, but my experience so far...

I've experimented with most of the theories so far, this is with a 10.5t TC and the wide RPM range is the key to unlocking the smoothest longest powerband you can get. I've tried short rpm ranges, turbo first then followed with boost, gearing up, gearing down, low start rpm and high start rpm, 0 delay on turbo, 0 - 10 on the motor (10.5t V3) etc.

My best setup to date -
FDR - 7.04
Endbell - 5 deg
DB - 0
Brake - 100 on esc, 80 on transmitter
Neutral - 10
Throttle - 3
VCO - 7.62
Timing - 55
Turbo - 15
Delay - 0.4
Ramp - 2
Start - 59**
End - 30000

As we have a kink in our main straight and a sweeper before it, the turbo could easily kick in part way through the sweeper and unsettle the car, you would then button off and have to get back on it and loose speed down the straight. The delay of 0.4 allowed the motor to get up to speed and the ramp of 2 made the transition seamless...the endbell timing on the V3 as mikky32 says is perfect on 5, this "seems" the true zero and the most torque.

Every time I've tried adding punch via timing via the esc it is always too much at the wrong time...I liken it to short shifting in a car, just depends on for which gear, yes 1st gear it goes like a rocket, you short shift to top gear, it lags and then can't pull any current until the motor hits its sweet spot again and rockets off again.

Just remember, timing is not torque!!! Timing can only be added when the torque is dropping off. Get the first part right with motor timing and gearing and use the timing to rocket it down the rest of the track I also find when my setup is getting close to linear acceleration the motor temp comes back into the sweet 60 - 65c range, so no chance of fade as an added bonus and extra play time when racing is over. Now I'll go back into my box

FLAT OUT

Does anyone in the Uk have any 10.5 setups for touring car. Im looking for rs setups for the BRCA championship tracks this year. Also what 10.5 motor do you guys here in England think is the best. Any help is good guys

mikky32

Thanks for the info.
I think that I will try it also one time with the V3.0 13,5T

The setup above maybe something for you?
Witch 10,5T motor and what kind of a track?