Infraction data log help

[sleekone]

I'd reduce your gearing slightly and make no other changes. Then test again. If you change 2-3 things you won't know which helped.

yep - i'm on board with this!

 

[sleekone]

Ok so maybe I can’t figure it out...how do I zoom on one run and get a nice looking graph where you can see the peaks clearly. When I zoom it still doesn’t look right...?

Ok so maybe I can’t figure it out...how do I zoom on one run and get a nice looking graph where you can see the peaks clearly. When I zoom it still doesn’t look right...?

Ugh nevermind! ?
ok so this is zoomed in from a previous run with the following setup
MMX8S
1717 motor +dual NTF fans
34S/35P gearing
2x 8000mAh gens-ace 4S 80C
18,800 uF cap pack
top speed was 114mph

i geared down to 30/34 and kept everything else the same and ran again. i also held the throttle wide open for at least 2-3 seconds
top speed was 103mph

 

[jkflow]

Seems like you are yanking the throttle at the last second in both cases. You should keep squeezing like you do in the first part of the ramp.
You can see that in your throttle curve and as a result the current spikes (almost 40A spike), no need for that overshoot.
Ripple looks ok.
RPM seem low but I have no reference point, my guess weight is high.

Keep in mind that I do not have a lot of speed race background but I do understand graphs, they are the tell all.

 

[jondilly1974]

Something strange going on here. With 35/34 gearing you should be over 160mph, maybe approaching 170mph. Voltage seems fine. Ripple is super low. Are you running Hoons?

 

[sleekone]

Something strange going on here. With 35/34 gearing you should be over 160mph, maybe approaching 170mph. Voltage seems fine. Ripple is super low. Are you running Hoons?

I agree...but what? Could my aerodynamics be affecting that much - my lid doesn’t quite stay closed completely due to a slight (?) fire recently..I’ve got a new body but I wanted to iron things out a bit more before I threw it on..


Yes I’m running Hoons. Was running all 4 closed disc but had a blowout a few weeks ago and had to run rears open Hoons.

Actually 1 of them blew out today on my last run.

Seems like you are yanking the throttle at the last second in both cases. You should keep squeezing like you do in the first part of the ramp.
You can see that in your throttle curve and as a result the current spikes (almost 40A spike), no need for that overshoot.
Ripple looks ok.
RPM seem low but I have no reference point, my guess weight is high.

Keep in mind that I do not have a lot of speed race background but I do understand graphs, they are the tell all.

I’ve got some ballast weight in the nose to keep it planted a bit more - my lid doesn’t quite stay closed and I’ve had it flip a few times. Not much weight through - a couple of the brass weight is it.

 

[jondilly1974]

Looks like you still have the nose fins in place. What about the rear wing? You want to trim or remove those.

 

[Mr.Duke]

Ok so maybe I can’t figure it out...how do I zoom on one run and get a nice looking graph where you can see the peaks clearly. When I zoom it still doesn’t look right...?

Ugh nevermind! ?
ok so this is zoomed in from a previous run with the following setup
MMX8S
1717 motor +dual NTF fans
34S/35P gearing
2x 8000mAh gens-ace 4S 80C
18,800 uF cap pack
top speed was 114mph
View attachment 100850

i geared down to 30/34 and kept everything else the same and ran again. i also held the throttle wide open for at least 2-3 seconds
top speed was 103mph
View attachment 100851

Plug into your esc and disable the low voltage cutoff. Without seeing the log data on your first pass 35/34 I assumed it was just overgeared but it’s clear now that you dipped hard under LVC (red horizontal line). Note how the light blue line drops rapidly as you dipped under the red line.

For future reference your Throttle IN and ESC Out lines should mimic each other, and any deviation should point to an issue.
- Edit to add picture of example

 

[LibertyMKiii]

I agree with @Mr.Duke
You actually see on the graph where the voltage dipped down (thin red line) and intersects the LVC bar (thick red line) the amps (green line) immediately go down, and the acceleration stops there....
I wouldn't change a thing on gearing and just adjust the LVC setting. The car was accelerating very hard up until that point and then sort of plateaued.

 

[sleekone]

I agree with @Mr.Duke
You actually see on the graph where the voltage dipped down (thin red line) and intersects the LVC bar (thick red line) the amps (green line) immediately go down, and the acceleration stops there....
I wouldn't change a thing on gearing and just adjust the LVC setting. The car was accelerating very hard up until that point and then sort of plateaued.
View attachment 100971

that makes good sense. i'm starting to understand how each of these interacts with each other so thank you all!!
i see it now on the log from a week ago too..RPMs drop as soon as voltage hits LVC. very cool to start to understand this stuff!

only problem is now i'm back stuck at work on a monday again! ? ??

 

[LibertyMKiii]

only problem is now i'm back stuck at work on a monday again! ? ??

Dude, you got to quit that job..... its getting in the way!

 

[sleekone]

Dude, you got to quit that job..... its getting in the way!

RIGHT?? ? ?

Plug into your esc and disable the low voltage cutoff.

what else do i need to be aware of when running once i disable LVC so i don't damage anything.? just keep my lipos fully charged - don't run them as long as normal, down too low or what?

 

[The Donut Man]

Typically we don't make more than 1-3 passes with our cars, but that's often because of motor & ESC temperature than battery voltage. Depending on my gearing, I almost never make more than 2 attempts at a run. I would say that's a safe place to start.

P.S. 100th post, woohoo

 

[jkflow]

Take a good look at your throttle curve, this is all cause and effect.
Your throttle curve has a steeper incline in the last second, this causes the current to go up at that time and your voltage drops below the red line shortly thereafter.
The pink line below is where your ideal throttle curve should have been for this run. Key is to avoid these abrupt changes.
This little change in incline immediately made your current jump (green) and red goes down as a result.

On your second graph it's even worse with respect to last second throttle pull, the fact that your batteries start out lower lets you hit LVC earlier and you do not see a higher spike in current. It actually hits LVC before you hit full throttle because of it. Either you had different batteries or they were already lower from a previous run, yo start out almost 1V lower. They crossed this red line at 260A while in your first graph you are at ~340A.

 

[sleekone]

Typically we don't make more than 1-3 passes with our cars, but that's often because of motor & ESC temperature than battery voltage. Depending on my gearing, I almost never make more than 2 attempts at a run. I would say that's a safe place to start.

P.S. 100th post, woohoo

ya i typically only make 1 or 2 passes but i don't always fully charge my lipos before the next session...just thinking if i disable LVC i should make that best practice to always have fully charged lipos..

Take a good look at your throttle curve, this is all cause and effect.
Your throttle curve has a steeper incline in the last second, this causes the current to go up at that time and your voltage drops below the red line shortly thereafter.
The pink line below is where your ideal throttle curve should have been for this run. Key is to avoid these abrupt changes.
This little change in incline immediately made your current jump (green) and red goes down as a result.

On your second graph it's even worse with respect to last second throttle pull, the fact that your batteries start out lower lets you hit LVC earlier and you do not see a higher spike in current. It actually hits LVC before you hit full throttle because of it. Either you had different batteries or they were already lower from a previous run, yo start out almost 1V lower. They crossed this red line at 260A while in your first graph you are at ~340A.


View attachment 100979

same batteries, different runs on different days...could just be my heavy handed throttle pulls??

 

[jkflow]

Don't think it's your pull on the initial voltage.
Prior both runs, you can see the max. @31.8V and on the other run it's 30.7, assuming you are on 8S that is 3.95V or 3.83, huge difference in used capacity.

 

[LibertyMKiii]

ya i typically only make 1 or 2 passes but i don't always fully charge my lipos before the next session...just thinking if i disable LVC i should make that best practice to always have fully charged lipos..

same batteries, different runs on different days...could just be my heavy handed throttle pulls??

Ya I never go out to speed run with anything other than fully charged packs. The car will start going 3-5 mph slower after each run! So typically after 2 runs its time to pack it up...

Then the packs sit on the bench getting back into storage discharge levels the rest of the day

 

[sleekone]

ok...i disabled LVC and ran 117mph back to back pretty much on 30/34 gearing, which is way better than previously - i couldn't get past 100ish on the same gearing with LVC active.. no other changers to my set up. oh but i also recalibrated my throttle to the ESC so i'm getting 100% now too...not sure how much more that gave me but probably a little as i was topping out at 94-98% previously..
here's the data from the first run:

 

[LibertyMKiii]

ok...i disabled LVC and ran 117mph back to back pretty much on 30/34 gearing, which is way better than previously - i couldn't get past 100ish on the same gearing with LVC active.. no other changers to my set up. oh but i also recalibrated my throttle to the ESC so i'm getting 100% now too...not sure how much more that gave me but probably a little as i was topping out at 94-98% previously..
here's the data from the first run:
View attachment 101013

Looks good, you got a solid 4+ seconds of full throttle and the speed nearly stopped climbing.
I assume that is 30t pinion and 34t spur?
Depending what your speed goals are your next move would be to move up the pinion. Ideally your amps will be in the high 300's when its nearing its maximum abilities... (increasing your gearing will drive up the amperage use and likely create more voltage drop too)(SMC V2's might help there. They are the highest C rating and lowest voltage drop LiPos on the market, but I say max-out what you have first)

The worlds top speed runners running over 150mph seem to always be in the 50k rpm range. The only way to get there is higher kv (around 2200KV)
25v * 2200kv = 55,000 rpm

 

[Mr.Duke]

ok...i disabled LVC and ran 117mph back to back pretty much on 30/34 gearing, which is way better than previously - i couldn't get past 100ish on the same gearing with LVC active.. no other changers to my set up. oh but i also recalibrated my throttle to the ESC so i'm getting 100% now too...not sure how much more that gave me but probably a little as i was topping out at 94-98% previously..
here's the data from the first run:
View attachment 101013

That’s a nice clean pass with good data to build off of on future runs. ?
I would start adding 1 tooth on the pinion side each session and analyzing data logs as you get faster with each outing.

 

[sleekone]

Looks good, you got a solid 4+ seconds of full throttle and the speed nearly stopped climbing.
I assume that is 30t pinion and 34t spur?
Depending what your speed goals are your next move would be to move up the pinion. Ideally your amps will be in the high 300's when its nearing its maximum abilities... (increasing your gearing will drive up the amperage use and likely create more voltage drop too)(SMC V2's might help there. They are the highest C rating and lowest voltage drop LiPos on the market, but I say max-out what you have first)

The worlds top speed runners running over 150mph seem to always be in the 50k rpm range. The only way to get there is higher kv (around 2200KV)
25v * 2200kv = 55,000 rpm

Thanks, it felt like a good pass as soon as I ran it. I’ve hit 120 so I just want to keep going now! I’d like to get to 125-130mph now on this set up.
So couple questions -
-Yes I’m running 30T pinion and 34T spur. What do you think of going to 29T spur instead of gearing up the pinion?
- What about aerodynamics - front and rear wings are still stock - should I trim them right down?
-so is it normal I’m still only hitting 33k ish rpm?
I feel like I can get more out of this without changing much - they were good runs but I still squiggle a bit with keeping it straight. Are you guys running AVC receivers? Or does that take away from power...I’m currently not.