Help with XL2 log data???

[RC-Monster Mike]

Originally Posted by Kirkinsb

Based on my experience, I am completely surprised by your max current of 240amps! Especially in a medium sized vehicle. My 28lb Baja 5t pulls 215 amps on pavement with NO tire spin. Meaning I am putting all the power to the ground... That is with the 2028 motor on 8s and running the crap out of it hard.

My Brushless E-Revo (more closely realated to a muggy than my 5t) also with an XL2 and a 1518 motor only pulls 106 amps on 6s...ripple is 1.8v with cap pack. And that is running mine wide-open-throttle...all the time really hard!!! So 240 seem really high to me....especially if you are just blipping the throttle. If I were to guess, I would say your motor is malfunctioning which is what caused your MMM2 to fail. Neither of mine cog in anyway shape or form.

Again, That is just my experience. Your current numbers are WAAAAY higher and different than mine and I have been running my baja 5t for about a year now. I was one of the first owners of the Castle Baja Conversion kit with the original Mamba XL ver 1. I would say you have a problem somewhere.

My XL2s are doing great! Lots of fun now.

Your numbers are low(especially the Muggy). What sample rate are you logging data at? I have seen 200 amps on a 10 pounds truggy in testing with an average draw of less than 30 amps during the run. A low sample rate will mask the true peaks. Also, any punch control or expo settings on the radio can also lower the recorded peak draw.

[magicald]

Anything is possible, but I literally have 5 runs total on this motor which was purchased new from CC...over the past 6 months I have completely rebuilt my muggy from the ground up off of an IRC chassis, new HD diffs, new drive shafts, new bearings,etc.

However, the cogging I'm seeing feels like the kind with less than optimal batteries...cogs a few feet then kicks in and is ok, or if you roll it and come on the throttle it doesn't cog at all.

I did briefly test my system without a pinion on and the log was perfect without load, so could my motor really be bad??

I have a neu 1521 I could try if I have enough 8mm bullets left....

[magicald]

Originally Posted by RC-Monster Mike

Your numbers are low(especially the Muggy). What sample rate are you logging data at? I have seen 200 amps on a 10 pounds truggy in testing with an average draw of less than 30 amps during the run. A low sample rate will mask the true peaks. Also, any punch control or expo settings on the radio can also lower the recorded peak draw.

The logging is set at default (I'll have to hook it up and check).

All other settings are at default... No punch control and radio is set on linear with no end points.

What's the best setting to change to tell if it's my batteries...if there is a setting?

[magicald]

Sorry, forgot to ask Mike, what log sampling rate do you suggest?

[Kirkinsb]

Originally Posted by RC-Monster Mike

Your numbers are low(especially the Muggy). What sample rate are you logging data at? I have seen 200 amps on a 10 pounds truggy in testing with an average draw of less than 30 amps during the run. A low sample rate will mask the true peaks. Also, any punch control or expo settings on the radio can also lower the recorded peak draw.

I checked the 5t and it was 2 samplings per second. All other settings were stock. No punch control, etc... If you set the sample rate much more than 2 per second, you won't get the entire run into the logging memory....you will only get 7 minutes or 14 minutes. Most guys at the HPI baja Forum are all pulling anywhere from 200 to 240 in their Castle Creations bajas....so, I think that my data is right on the money with it being around 220ish.

My 11lb revo (GPSed at 62mph) is also on 2 samplings per second....and according to the data log pulled a max of 106.5amps. All other settings are stock.

So assuming Castle Bajas pull 230ish...it makes sense to me that a 10lb truck would pull about half the amps as a 28lb truck. Seems just about right to me.

A ten pound muggy pulling 200amps!!!...what the heck motor is in it?!?!?!

All I can say is at a sampling rate of 2/second, all other settings stock, I was pulling 106 in my 11lb revo and 225ish in my 28lb 5t according to the Data log from each mamba XL2.

You have to agree that if he was just blipping the throttle and already getting 240amps...something seems odd when compared to results I have...plus all the other baja owner who have converted to the XL2 and 2028 motor who are getting about 230ish amps as well. That is all I know. a 10 lb muggy pulling 240 amps just blipping the throttle seem high....with the little bit of data logging experience I have had and read about.

Don't know if this helps...I may try a higher sampling rate...but that sucks because I would only get 1/3 or 1/2 the run into memory. Do you think 2/second sampling rate is sufficient?

Was that muggy pulling 200ish using a MambaXL2? let us know.

[RC-Monster Mike]

Kirkinsb - 2 samples per second data rate explains your low numbers for sure - you are simply missing the microsecond peak currents that happen. In my experience, the peak draw will ramp down very quickly once the car is rolling - a 200+ amp spike could be down to 120 amps within the same second. 2 samples/second frame rate will not show this, though. I understand that a higher frame rate will result less log time, but it will also yield higher data resolution so you can see more detailed data, albeit for s shorter time. Besides....do you really need to log the entire run every time? Please maximize your frame rate, gather some data, and report back. You can always change the frame rate back afterwards, but I think you will be surprised at what you see.

Also, while the Baja is a larger, heavier vehicle, it also typically is used under a higher voltage and will have less traction than an overgeared Muggy(4wd) with large, heavy tires. On the surface, logic may say that a car that is half the size will draw half the current, but in truth, there are many variables that will quickly dispell this logic. Also, a throttle "blip" can be no different than a full on drag race launch, but over a shorter time period. The actual peak current happens over a very short time period(1/10 second or even less) so it does not surprise me to see 200+ peaks on a heavy, overgeared 4wd monster truck.

magicald - The highest log rate will give you the highest resolution. In reality, the average draw is typically fairly low, but there are microsecond peak currents that are very high. Personally, I have only used the highest available frame rate, as I normally am only logging data when I am trying to dial in a setup or test a component(battery, motor, etc.). The highest resolution will provide the most information in a short period of time. The beautiful thing is that you can change the frame rate! I think it is wise to maximize the frame rate occasionally to properly visualize the truest data, but there is nothing wrong with a lower frame rate to gather more general data over a longer period.


In my opinion, you simply can't draw any accurate conclusions from data logged at different frame rates - logging at a low frame rate will mask peaks.

[magicald]

Thanks for the input Mike. I have went with my gut and ordered a new TP g6 65C 6S battery...why I keep going back to this is that the hyperion I have is used...I'm not sure how old it is, but I've had it for 1 year and even though it charges normally, is not puffed, and balances nicely, I don't think it has enough amperage for my set up.

I'm going to what to run it until I get the new lipo. I'll change my sampling rate and let you guys know what I find.

May need to with to 17mm truggy tires though I love the way the large 55 series wheels look on the muggy...it is a monster-truggy after all!!

[Kirkinsb]

Originally Posted by RC-Monster Mike

Kirkinsb - 2 samples per second data rate explains your low numbers for sure - you are simply missing the microsecond peak currents that happen. In my experience, the peak draw will ramp down very quickly once the car is rolling - a 200+ amp spike could be down to 120 amps within the same second. 2 samples/second frame rate will not show this, though. I understand that a higher frame rate will result less log time, but it will also yield higher data resolution so you can see more detailed data, albeit for s shorter time. Besides....do you really need to log the entire run every time? Please maximize your frame rate, gather some data, and report back. You can always change the frame rate back afterwards, but I think you will be surprised at what you see.

Also, while the Baja is a larger, heavier vehicle, it also typically is used under a higher voltage and will have less traction than an overgeared Muggy(4wd) with large, heavy tires. On the surface, logic may say that a car that is half the size will draw half the current, but in truth, there are many variables that will quickly dispell this logic. Also, a throttle "blip" can be no different than a full on drag race launch, but over a shorter time period. The actual peak current happens over a very short time period(1/10 second or even less) so it does not surprise me to see 200+ peaks on a heavy, overgeared 4wd monster truck.

magicald - The highest log rate will give you the highest resolution. In reality, the average draw is typically fairly low, but there are microsecond peak currents that are very high. Personally, I have only used the highest available frame rate, as I normally am only logging data when I am trying to dial in a setup or test a component(battery, motor, etc.). The highest resolution will provide the most information in a short period of time. The beautiful thing is that you can change the frame rate! I think it is wise to maximize the frame rate occasionally to properly visualize the truest data, but there is nothing wrong with a lower frame rate to gather more general data over a longer period.


In my opinion, you simply can't draw any accurate conclusions from data logged at different frame rates - logging at a low frame rate will mask peaks.

Good info..makes sense.... I will try the highest frame rate one of these days and see what happens.... Also good info about how higher voltage and current affect each other. Sounds good. I am just glad the XL2s seem to have the bugs worked out. They perferm great. Thanks

[Pdelcast]

Originally Posted by Kirkinsb

Good info..makes sense.... I will try the highest frame rate one of these days and see what happens.... Also good info about how higher voltage and current affect each other. Sounds good. I am just glad the XL2s seem to have the bugs worked out. They perferm great. Thanks

Just for everyone's benefit--

The ICE datalogger (used in the XL/XL2) actually samples the current several times during each PWM cycle (synchronously), and then keeps a running average of the results. The samples are then written to flash memory at the programmed "sample rate."

So the sample rate is only the rate at which the averaged samples are written to memory -- not the rate at which the controller samples the current...

Make sense??

[Kirkinsb]

Originally Posted by Pdelcast

Just for everyone's benefit--

The ICE datalogger (used in the XL/XL2) actually samples the current several times during each PWM cycle (synchronously), and then keeps a running average of the results. The samples are then written to flash memory at the programmed "sample rate."

So the sample rate is only the rate at which the averaged samples are written to memory -- not the rate at which the controller samples the current...

Make sense??

Ok, so my readings at 2/second are probably fairly accurate? And I am not missing any huge amounts of data by not using the 5/second setting? Yes/No? Hmmm, interesting. Is their much benefit to having the data written 5/second as opposed to 2/second since it is averaged? thanks Patrick.

[brian015]

Originally Posted by Kirkinsb

Ok, so my readings at 2/second are probably fairly accurate? And I am not missing any huge amounts of data by not using the 5/second setting? Yes/No? Hmmm, interesting. Is their much benefit to having the data written 5/second as opposed to 2/second since it is averaged? thanks Patrick.

No, your readings are more averaged than if you had the data written at a faster rate - so the real peak of the spike is averaged with lower currents on either side of the peak giving a lower average current written to the memory. Writing data at a faster rate should include less averaged data - so truer to the actual curve.

I think.

[RC-Monster Mike]

Yeah...what he said(brian015). :)

[magicald]

So I was bored tonight, waiting on my new battery to arrive (which will hopefully solve my start cogging problem) so I decided to log a run with only the load of the drivetrain - wheels off the ground. This is a very short run, but numbers don't look bad at all. I used 10 samples/sec for the logging.

I guess I'm trying to reassure myself that my motor is okay...

[magicald]

I don't have enough male 8mm bullets to try my 1521 motor, it would be too much trouble to swap them from my 1717.

Any other ideas to test my 1717? I don't have another rig to try it in...I read about the "drill" method on some aircraft sites to make sure that voltage was similar between all leads and check and make sure no lead shorts is in continuity with the motor case.

Also, I ordered some 17mm adapters to put truggy wheels on it to try that if the battery doesn't help.

[magicald]

A few quick pics...sorry for the phone quality images