X-File: Understanding VESC: the difference between "battery amps" and "motor amps"
Ackmaniac, post:215, topic:15995 Wrote:But will that lead to a even acceleration?

@Ackmaniac It won't lead to even acceleration strictly speaking (due to wind, rolling resistance, incline, etc.), but it will feel like even acceleration to the rider because it is even access to electrical source power at all physically possible rpms.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/216,2017-02-01 02:13:22 UTC
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Ackmaniac, post:215, topic:15995 Wrote:And why does my vesc shut down when I do full throttle with 10/10/10

@Ackmaniac so we have 1 motor and 1 VESC
pack voltage: 38V nominal = 10S x 3.8V nominal per cell
ohm resistance: 0.016 ohm
motor amp limit: 10A

go to an ohm's law calculator and enter:

10 A & 0.016 ohm

this gives 4 values:

0.16 V <-- effective PWM voltage @ full throttle @ standstill
10 A <-- this is your "Motor / Absolute" amp limit setting
1.6 W
0.016 ohm

0.04 A = battery watt limit: 1.6 W / pack voltage: 38V nominal

0.04 A  <-- this is the maximum "Battery" amps @ full throttle @ standstill

this gives:

10/10/10 batt/motor/absolute max amp limit settings

this gives:

Duty Cycle 0.42105% @ Full Throttle @ Standstill = (Effective PWM voltage @ full throttle @ standstill: 0.16 V / Pack Voltage: 38 V) x 100

this gives:

FULL THROTTLE = 1.6 W W Electrical @ full throttle @ standstill

"Motor heating" averaged throughout motor will be equivalent to maximum 0.04 A "battery amps".

Ackmaniac, post:215, topic:15995 Wrote:And why does my vesc shut down when I do full throttle with 10/10/10

@Ackmaniac In simple terms at full throttle @ standstill your motor has maximum 1.6 W (0.04 A Battery Amps) available electrical power.

",0,2,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/218,2017-02-01 02:23:00 UTC
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Ackmaniac, post:219, topic:15995, full:true Wrote:But it shuts down at any speed. Doesn't matter if standstill or half speed.

devin, post:218, topic:15995 Wrote:@Ackmaniac In simple terms at full throttle @ standstill your motor has maximum 1.6 W (0.04 A Battery Amps) available electrical power.

Ackmaniac, post:217, topic:15995 Wrote:Why does my vesc shut down with 10/10/10.

@Ackmaniac In simple terms your motor and VESC won't work with only 1.6W (0.04 A Battery Amps) of available electrical power for the motor, full throttle @ standstill.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/220,2017-02-01 02:29:57 UTC
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Ackmaniac, post:221, topic:15995 Wrote:But it also shuts down when I do 25 km/h and give full throttle.

Ackmaniac, post:213, topic:15995, full:true Wrote:1 motor
0.016 resistance
360 watts
10S liion
Even acceleration.

devin, post:214, topic:15995 Wrote:@Ackmaniac In simplest terms your settings need to be 10/150/150 batt/motor/absolute.

@Ackmaniac The real test to do is:

10/150/150 batt/motor/absolute

Does full throttle = ~360W electrical @ all physically possible rpms (including very close to 0rpm)?

I'll bet it does.

Is Duty Cycle ~6.31% @ Full Throttle @ Standstill?

I'll bet it is.

",0,2,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/222,2017-02-01 02:38:46 UTC
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Ackmaniac, post:223, topic:15995 Wrote:Do you have a idea why that happens at 10/10/10

@Ackmaniac yes, i've already told you full throttle @ standstill = 1.6W (0.04A battery amps)

devin, post:218, topic:15995 Wrote:Duty Cycle 0.42105%

@Ackmaniac ^ i can only assume this 0.42105% duty cycle @ full throttle @ 0 rpm is too low for the VESC and results in some type of mathematical logic error in the VESC.

",0,2,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/224,2017-02-01 02:47:06 UTC
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Ackmaniac, post:225, topic:15995, full:true Wrote:But I am not doing 0 rpm. I am already at 1000 or 2000 rpm and the result is the same. That's really dangerous. And why do you always mention that I am doing 0 rpm or standstill or whatever. Also the brakes don't work anymore for like 3 seconds after I did full throttle. And you say that the power is too low. But half throttle works without any issues. Only at full throttle the VESC shuts down. Why is that.

devin, post:224, topic:15995 Wrote:@Ackmaniac ^ i can only assume this 0.42105% duty cycle @ full throttle @ 0 rpm is too low for the VESC and results in some type of mathematical logic error in the VESC.

@Ackmaniac as I mentioned, I suspect the 10/10/10 batt/motor/absolute settings themselves are creating a mathematical logic error in the VESC.

In simple terms, if you use 10/150/150 batt/motor/absolute (based on your rig), you will have:

Full Throttle = ~360W Electrical @ all physically possible rpms (including very close to 0rpm)

Ackmaniac, post:213, topic:15995, full:true Wrote:1 motor
0.016 resistance
360 watts
10S liion
Even acceleration.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/226,2017-02-01 02:58:49 UTC
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Ackmaniac, post:227, topic:15995, full:true Wrote:OK I tried 10/40/40. I would not call that even acceleration. Has a lot of acceleration at very low speed but the acceleration gets lower and lower the faster I go. And when I do full throttle it still shuts down. If this is also by a mathematical error why should there be a difference if I would use 10/150/150

@Ackmaniac you won't know till you try will you? @hummie rides around at 48/200/200 all day with his funny looking long wheel.

Hummie, post:41, topic:16953, full:true Wrote:there's a lot of people annoyed with devin's repeated math but the math isn't wrong! telling people it's wrong is not helping. all those people who think they know what's going on, yet are saying devin's math is wrong..prove it. I ride 200 motor amps. I have almost no cogging and super smooth acceleration and exact power output as determined by the math. the proof is in the pudding. are we here on the forum to figure out how things work and make things better, because they definitely are for me, or are all you guys going to keep grumbling and flagging the real info while you claim it isn't. egos abound and they're in the way. if we're talking about safety this is the way there. control of what your power output is at all rpms.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/228,2017-02-01 03:06:46 UTC
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Ackmaniac, post:229, topic:15995, full:true Wrote:So you advice me to use even higher settings while the lower settings don't work. It gets already dangerous when the power drops out with my low settings. Can't imagine what happens when I would use even higher settings. Apart from the idea that it is a logical error, do you have any other idea? And why does it work for hummie and not for me?

@Ackmaniac in simple terms, yes.

Hummie, post:41, topic:16953, full:true Wrote:all those people who think they know what's going on, yet are saying devin's math is wrong..prove it. I ride 200 motor amps. I have almost no cogging and super smooth acceleration

devin, post:24, topic:15995 Wrote:I consider the 48/200/200 test a success because the VESC didn't snap, @Hummie rode around the block, and the $100 I put down on the VESC is safely back in my pocket. (and low speed "cogging" is basically eliminated, acceleration is much quicker and steadier) Confusedweatsmile:

i asked @Hummie if he plans to go back to his old settings and his answer was "no."

devin, post:222, topic:15995 Wrote:@Ackmaniac The real test to do is:

10/150/150 batt/motor/absolute

Does full throttle = ~360W electrical @ all physically possible rpms (including very close to 0rpm)?

I'll bet it does.

Is Duty Cycle ~6.31% @ Full Throttle @ Standstill?

I'll bet it is.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/230,2017-02-01 03:10:56 UTC
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Ackmaniac, post:231, topic:15995, full:true Wrote:In simple terms, that sounds to me you have no clue why it shuts down and you don't give a shit if I or anybody else gets hurt.

@Ackmaniac why does @Hummie's VESC work all day at 48/200/200?

That's @Hummie full throttle = 1660W electrical @ all physically possible rpms (including very close to 0rpm) on a funny-looking long hub motor.

@Ackmaniac maybe it has to do with your possible "throttle curve adjustment settings?" i suggest getting rid of those for the test.

Hummie, post:41, topic:16953, full:true Wrote:all those people who think they know what's going on, yet are saying devin's math is wrong..prove it. I ride 200 motor amps. I have almost no cogging and super smooth acceleration

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/232,2017-02-01 03:27:46 UTC
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Ackmaniac, post:233, topic:15995 Wrote:10/40/40

@Ackmaniac this is still only 25.6W (0.673 Battery Amps) full throttle @ standstill

still far too low W (25.6 W - Electrical Watts) @ full throttle @ standstill

still far too low A (0.673 A - Battery Amps) @ full throttle @ standstill

still logic error VESC

Ackmaniac, post:213, topic:15995, full:true Wrote:1 motor
0.016 resistance
360 watts
10S liion
Even acceleration.

Hummie, post:41, topic:16953, full:true Wrote:I ride 200 motor amps. I have almost no cogging and super smooth acceleration

devin, post:24, topic:15995 Wrote:I consider the 48/200/200 test a success because the VESC didn't snap, @Hummie rode around the block, and the $100 I put down on the VESC is safely back in my pocket. (and low speed "cogging" is basically eliminated, acceleration is much quicker and steadier) Confusedweatsmile:

i asked @Hummie if he plans to go back to his old settings and his answer was "no."

devin, post:222, topic:15995 Wrote:@Ackmaniac The real test to do is:

10/150/150 batt/motor/absolute

devin, post:222, topic:15995 Wrote:Does full throttle = ~360W electrical @ all physically possible rpms (including very close to 0rpm)?

I'll bet it does.

Is Duty Cycle ~6.31% @ Full Throttle @ Standstill?

I'll bet it is.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/234,2017-02-01 03:35:57 UTC
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