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Old 03-18-2010, 09:27 AM   #13366
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Thank you very much theisgroup.

I think along these lines too, but am not sure abot the current limitation idea. In the graph posted above you can see the current drawn is not at a very high value and rising when the dip happens. If this doesn't convince you, I have a maximum current draw of about 50A at the beginning of the race and the battery seems to cope very well with that (no drops). My batteries are quite new and 50C (5000mAh IP). The wires hold easily above 100A no worries.

I think it may be another effect, hopefully not software related, but this can only be clarified by the Teking Team. Hopefully they see this thread, if not we can open a separate thread on this topic.

But if the problem is not in the software, then it has to be in the electronic hardware, perhaps a problem in the final control stages of the speedy (the power MOSFETS). If they have don't a high enough slew rate ( i.e. if they don't open up fast enough) then one can expect such drops as the transistors "catch up". Still somewhat unlikely idea, because as I explained above, when I pull off, the current increases instantly above 50A with no problems.

To put to rest some of the above suggestions, the radio signal float is minimal and the speedy can see the WOT command very well, otherwise it would not apply the turbo. Counting on the graph above, the turbo is applied correctly at .5 delay from the first front of the WOT signal. And yes, I have done the calibration trick and the problem still remains.

It is a very complicated problem, I am sure, but I feel somewhat more reassured now that I know other people have noticed it. Thank you very much again, and hope we'll et to the bottom of this. If Team Tekin finds there is a problem indeed, I am happy to supply more data and help in addressing the problem. After all, if the issue is fixed, we can all only benefit, Team Tekin as much as us.
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Old 03-18-2010, 09:32 AM   #13367
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Originally Posted by Mr. Paroxysmal View Post
Is it possible to remove the solder post on the Tekin speedo and solder the wire directly to the solder pad? The reason I ask is because there are couple of time on my local tract the that wire got de-solder and burn the speedo. Need responce.
I was told those GOLD BARS are actually acting as a HEAT SINK for the speedo and you DO NOT want to remove them...not 100% sure but I have no problem soldering wires onto those posts.
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Old 03-18-2010, 09:45 AM   #13368
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Originally Posted by niznai View Post
Thank you very much theisgroup.

I think along these lines too, but am not sure abot the current limitation idea. In the graph posted above you can see the current drawn is not at a very high value and rising when the dip happens. If this doesn't convince you, I have a maximum current draw of about 50A at the beginning of the race and the battery seems to cope very well with that (no drops). My batteries are quite new and 50C (5000mAh IP). The wires hold easily above 100A no worries.

I think it may be another effect, hopefully not software related, but this can only be clarified by the Teking Team. Hopefully they see this thread, if not we can open a separate thread on this topic.

But if the problem is not in the software, then it has to be in the electronic hardware, perhaps a problem in the final control stages of the speedy (the power MOSFETS). If they have don't a high enough slew rate ( i.e. if they don't open up fast enough) then one can expect such drops as the transistors "catch up". Still somewhat unlikely idea, because as I explained above, when I pull off, the current increases instantly above 50A with no problems.

To put to rest some of the above suggestions, the radio signal float is minimal and the speedy can see the WOT command very well, otherwise it would not apply the turbo. Counting on the graph above, the turbo is applied correctly at .5 delay from the first front of the WOT signal. And yes, I have done the calibration trick and the problem still remains.

It is a very complicated problem, I am sure, but I feel somewhat more reassured now that I know other people have noticed it. Thank you very much again, and hope we'll et to the bottom of this. If Team Tekin finds there is a problem indeed, I am happy to supply more data and help in addressing the problem. After all, if the issue is fixed, we can all only benefit, Team Tekin as much as us.
i would agree with you on the current, but remember the sentry and all the other units that I have looked at samples data every 1/10th of a second. that mean you will be missing data in between those time. these units do not average ever 1/10th, they sample every 1/10th of a second.

one reason that caps are uses is because batts can not handle the transitions from power requirements. think of a car stereo. most guys were running caps because the batterys could not handle the transitions from no power requirement to full power requirement. this is what I think the issue is. it is when the bass hits and the amp can not get the power from the battery to handle the power requirements from the amp.
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Old 03-18-2010, 09:54 AM   #13369
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Watch also if you steer a bit or when there are some small bumps in the track you can have the same. This are most of the time just very small rpm losses but with some wind it also can do these things.
Than how much was the total timing?
Did you try a timing of around 40 in total to see what it does?
The battery what you say can be a thing that can cause it but than I think that you use to much total timing when it is extreme.

I don't have a data logger but I want one.
I hope in the next update that you can read this info with the Tekin speedo.
The new GM speedo's have also a temp meter for the motor. It works only with motors that have on in them but this would also be a great option.
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Old 03-18-2010, 10:07 AM   #13370
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Originally Posted by theisgroup View Post
that is what I am thinking when you see the couple of "double" dips in the graph that was posted. I don't see that in my setup. the only dip i see is when I first hit full throttle. I know I am not maxing out because just before that point, I have no timing added and my start rpm is 4000-4500 for 17.5. after i hit full throttle, the rpm just get to about 5000-5300 before it dips. my end rpm is 6800 and I add 50 degrees of timing. so i am adding ~18 degrees per 1000rpm. so i would only be at 18 or so degree. that should not be overtimed at that point in the motor. my turbo delay is .6, so turbo would not be kicking in either.
here's a test

if you're adding 18 degrees every 1000rpm... change the rev range to add 9 degrees every 1000rpm (double the rev range) and see if you get the dips ?

we found that on slow corners with 13.5 that the motor would be around 12,000 rpm and about 30,000 rpm by the end of the straight, so your end rpm is coming in very early in the rev range.

This is just a thought, but it sounds like too much timing, too quickly. I may well be wrong, but it's worth a shot to see if it makes a difference on the logger.

Ignore what it feels like to drive and if it's slow, no punch etc for now.. just test if the rpm "dips" with a much wider rpm range or not
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Old 03-18-2010, 10:10 AM   #13371
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Originally Posted by mikky32 View Post
Watch also if you steer a bit or when there are some small bumps in the track you can have the same. This are most of the time just very small rpm losses but with some wind it also can do these things.
Than how much was the total timing?
Did you try a timing of around 40 in total to see what it does?
The battery what you say can be a thing that can cause it but than I think that you use to much total timing when it is extreme.

I don't have a data logger but I want one.
I hope in the next update that you can read this info with the Tekin speedo.
The new GM speedo's have also a temp meter for the motor. It works only with motors that have on in them but this would also be a great option.
Total ESC timing is 50 on the boost but as can be seen from the graph, the drop happens before all boost is applied. I don't know what the actual timing is ont he motor, but externally is set to 0 (as said above, this is a 17.5 SP V3).

The datalogger will give you the temperature. My motor is about 70deg C at the end and the temperature increases steadily at a normal rate throughout the race (5 minutes). I think that is quite normal.

We race indoors, no wind to worry about.

About bumps, I think that should not affect the ESC this way, if at all. If anything, I can show you a graph where there is obvious wheelspin from going over bumps, but no RPM/current drop precedes it.

I have considered steering inputs as the cv joints we use are not real CV (that is constant velocity) joints, but the frequency should be different and as explained above, I was ont eh main straight which by definition has no corners, so steering inputs (if any) would ahve been minimal. There is a possibility that the steering servo was fighting against some wheel movement thus drawing some current and potentially depleting the battery but again, that is very unlikely and I would expect the effect would be a lot more powerful in corners where the steering really has to fight the car's inertia to make it go around corners. The graph suggests that is not the case.
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Old 03-18-2010, 10:21 AM   #13372
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Originally Posted by chris_dono View Post
here's a test

if you're adding 18 degrees every 1000rpm... change the rev range to add 9 degrees every 1000rpm (double the rev range) and see if you get the dips ?

we found that on slow corners with 13.5 that the motor would be around 12,000 rpm and about 30,000 rpm by the end of the straight, so your end rpm is coming in very early in the rev range.

This is just a thought, but it sounds like too much timing, too quickly. I may well be wrong, but it's worth a shot to see if it makes a difference on the logger.

Ignore what it feels like to drive and if it's slow, no punch etc for now.. just test if the rpm "dips" with a much wider rpm range or not
i did try extending the rpm range. but all it did was delay when I started to see the dip.

As far as too much timing to fast. I am not so sure. from the logs that I have in 17.5, on our track, my car was dipping down into the 2500rpm range on the slowest corner and around 3000 in all corners. so my start is after the motor has already started to utilize it's torque. and as far as max rpm, in 17.5 I was able to get the motor to sing up to 17,000. but the laptimes were slower because i had to motor down. with the gearing I felt was best my rpm in 17.5 was only 11,500-12,000 and that is only in the straight. around the infield i was always in the 8000. my end rpm allow for the motor to hit full timing boost in the infield with a little time allowance for the motor to get to full speed. also I run 0 timing on a duo1 and at 5000rpm, where my dip is seen, the speedo only has 18 degrees into it. at 18 degrees of advance, the motor is still mostly torque and has added very little rpm. motor torque and rpm are inversely related. they do not conver linear. as you loose torque you gain very little rpm. to a point. and then you loose very little torque and gain rpm very quickly. that point on a duo1 is 30 degrees or so. once you hit 30, the rpms just increase exponentially.

this past weekend, if i did not give away my motor, rollout and speedo setup in stock, I would have been 2 laps on the entire field. this includes a racer that is generally pretty close in speed as myself and made the A in vegas. and in my 13.5 car, i was pulling every car on the track including Dumas. the only car that was faster was the guys that I gave my setup to. and he was only pulling 1 foot on the back straight.
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Old 03-18-2010, 10:25 AM   #13373
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I have considered steering inputs as the cv joints we use are not real CV (that is constant velocity) joints, but the frequency should be different and as explained above, I was ont eh main straight which by definition has no corners, so steering inputs (if any) would ahve been minimal. There is a possibility that the steering servo was fighting against some wheel movement thus drawing some current and potentially depleting the battery but again, that is very unlikely and I would expect the effect would be a lot more powerful in corners where the steering really has to fight the car's inertia to make it go around corners. The graph suggests that is not the case.
i agree on this point because i see it in 1/12 and i run a rx pack so no draw on power from the main pack from the rx or servo
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Old 03-18-2010, 10:26 AM   #13374
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Ok and the Turbo delay was on 0,1?
Did you try an higher Turbo delay?
I'm just thinking of some things that can be the problem.
Sometimes it are the strangest things that can cause a thing that you would not think of in the first place.

Keep the total timing max on 60 to 65 degrees.

Do you feel the power loss wile racing?
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Old 03-18-2010, 10:40 AM   #13375
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i did try extending the rpm range. but all it did was delay when I started to see the dip.
I was hoping you'd say that

so the dip came later... try extending the range more and more and see if the dip goes away at all.. if it keeps getting later and later, you should get to a point where it doesn't happen at all.

this is really a minor issue as it's not causing you any lost time on the track, but I'm curious now hehe
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Old 03-18-2010, 10:44 AM   #13376
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Originally Posted by chris_dono View Post
I was hoping you'd say that

so the dip came later... try extending the range more and more and see if the dip goes away at all.. if it keeps getting later and later, you should get to a point where it doesn't happen at all.

this is really a minor issue as it's not causing you any lost time on the track, but I'm curious now hehe
sorry, I ment later in the run. but still right after you hit full throttle. i did notice that with no timing advance set in the speedo, i never see this strange dip

i think it is a minor issue. I have seen it since i posted about using the sentry. so I have noticed it in many logs for like 3+ months now. what was concerning me was more in 13.5 the dip is almost 4000rpm. that I would think is pretty noticable on the track. and may almost feel like the motor was bogging down. so people without a data logger might think this feeling was over gearing. which from all my testing is not the case.

and I do not like the wide range rpm setting. i feel that it makes the motor feel soft and just add alot of heat. when ever I run the wide band the motor is usually 10-15 degrees hotter then with the narrow band. but the wide band seams to be more forgiving on gearing. the narrow band, I have found 1 tooth to make .2 a difference on the track.
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Old 03-18-2010, 10:53 AM   #13377
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Originally Posted by mikky32 View Post
Ok and the Turbo delay was on 0,1?
Did you try an higher Turbo delay?
I'm just thinking of some things that can be the problem.
Sometimes it are the strangest things that can cause a thing that you would not think of in the first place.

Keep the total timing max on 60 to 65 degrees.

Do you feel the power loss wile racing?
my delay is .6

total timing is 61

and did not feel a power loss in 17.5 in 13.5 somethimes if feels like the motor is bogging down, but then it gets out of the hole like a bullet. so i do not see a time loss in lap times
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Old 03-18-2010, 11:13 AM   #13378
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my delay is .6

total timing is 61

and did not feel a power loss in 17.5 in 13.5 somethimes if feels like the motor is bogging down, but then it gets out of the hole like a bullet. so i do not see a time loss in lap times
than maybe it is a minor reading thing from the sensor.
4000RPM loss you will feel I think. especially with a 17,5T.

Maybe Randy can say what it is?
Did you mail him about it?
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Old 03-18-2010, 11:26 AM   #13379
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than maybe it is a minor reading thing from the sensor.
4000RPM loss you will feel I think. especially with a 17,5T.

Maybe Randy can say what it is?
Did you mail him about it?
it's 4000 in 13.5 and yes, i have pingged randy on it
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Old 03-18-2010, 11:37 AM   #13380
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sorry, I ment later in the run. but still right after you hit full throttle. i did notice that with no timing advance set in the speedo, i never see this strange dip

i think it is a minor issue. I have seen it since i posted about using the sentry. so I have noticed it in many logs for like 3+ months now. what was concerning me was more in 13.5 the dip is almost 4000rpm. that I would think is pretty noticable on the track. and may almost feel like the motor was bogging down. so people without a data logger might think this feeling was over gearing. which from all my testing is not the case.

and I do not like the wide range rpm setting. i feel that it makes the motor feel soft and just add alot of heat. when ever I run the wide band the motor is usually 10-15 degrees hotter then with the narrow band. but the wide band seams to be more forgiving on gearing. the narrow band, I have found 1 tooth to make .2 a difference on the track.

I don't understand how a wide band will make the motor hotter... all that happens with a narrow band is you get the timing quicker and therefore, for longer than with a wider band.
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