Motor settings not reaching nowhere its potential?

ESK8 Electronics
1

wanted to run my setting by, see if i’m doing something wrong.

this is coming from what used to be a 6374 dual drive, 12s4p setup. had to take one of the motors off for inspection / replacement so will be running it mono until it’s replaced.

here’s motor settings for mono drive:

here’s what i’m getting at max power draw:

image.png471×625 415 KB

i have batt max set at 70a but going up hill under hard acceleration it’s only drawing 28amps from the battery.

is there some setting i’m missing?

in dual drive, i’ve hit max batt 80amp draw.

2

Does it also feel like only 28 amps going up hill. Or does it feel like more

3

Would voltage sag be a culprit here?

4

definitely feels underpowered

I was seeing about 3v sag, but amp delivery should be unchanged. my understanding is voltage and amp draw should be inversely proportional?

5

It’s probably your drivetrain. That might be the maximum amount of torque your system can actually transmit with one belt/pulley. What belt width and motor pulley size are you using?

6

It’s not a 1:1 ratio, but more voltage, less amps. less voltage, more amps, yes.

But that’s not your problem here.

Could be a couple of things. Since I don’t know what your settings were before, it’s not clear if this is the problem or not.

But the VESC limits work by using which ever limit is lower: motor or battery. Devin had formulas that he claims worked, @Ackmaniac disagrees with these formulas (i’m somewheres in the middle), but has not provided any formulas either so that you can tell which one is hit first. Put the motor amps up to 100 and see if you get more battery amps. I would suspect this is your problem.

1 Like
7

Is this on the same battery pack? Could it be batteries can’t deliver so many amps?

At low speeds and hard acceleration I would expect the vesc to hit motor max limit while at higher speeds the bat max should be the limit factor.

I run foc on focboxes and I never hit my battery max but it’s not far off, at most 2-3 amps lower…

If you run ackmaniac firmware could it be you have W limit on?

8

15mm width, 15/40 tooth

yea, LG HG2 12s4p. checked connections and everything looks good and all P packs are balanced

sure, ill give it a go later

9

Heat is probably your issue here…not your settings. I bet your hitting vesc thermal throttling(FETs) going uphill with one motor

10

Just do us all a favour and make a video with the app while you go uphill. Then I can explain you what is happening in detail. Guess battery cutoff or temperature is the limiting factor here. But with a video I think I can tell you exactly.

2 Likes
11

What the meistro said ^^^ video log :wink:

12

you won’t hit your battery max amps unless you’re at 100% duty cycle I’m pretty sure. maybe you need to up your motor amps so you have the amps to even get to the higher speeds, and therefore higher duty cycle, to fully get to your battery amp limit. what’s your motor amp setting? I like 120 motor amps.
with the pic you posted you’re only at 60% duty cycle.

13

Based on the calculations I just did, you are only capable of transmitting about 1200 to 1350 W (depending on belt length) for a single drive with 15T motor pulley and 15mm HTD belt

This is right inline with the 1244W you recorded

14

Would you mind sharing the formula you used considering belt length as a factor?

15

its at 80a now, will give this a go later

max temp is below 60c at top of the hill climb. where does it start throttling?

pardon the shitty quality, the glass covering the camera is shattered right now

16

Maybe double check ppm value and see if it goes all the way up to 100%

17

That’s 140f. Throttling default is 135F if im not mistaken.

Sounds like it is for sure thermal throttling if your getting up in the 140s

18

That is a really strange case. It’s not limited by the the battery voltage and also not by the temperature. Please post screenshots of your settings. Maybe something is wrong there.

Do you have a BMS between the Battery and the FOCBOX?

19

yes, 80a bestech bms, using it for discharge.

i don’t think it’s the bms because in dual drive it gets up to 80a batt discharge.

i’ll take a screenshot of settings later tonight, need to make some adjustments anyway.

20

Could be that one of your series packs is too far off from the other cells so that the BMS reduces the power. If you have the chance try it without the BMS and let us know if it makes a difference.

I wouldn’t include a BMS in the discharge cycle because you never know what they do in detail. Would only use it for charging with charger. On 3 of my boards i don’t even use a balancer at all and check each series pack from time to time. Max difference so far was 0.01V (Li-Ion). With a Li-Po i think it is necessary to balance but with Li-ion and a adjustable charger i would set it to 4.15V for each cell and then you should have enough wiggle room if the cells start to drift.