Acceleration Temperature Decrease Visualizer [Serious]

[fessyfoo]

in v3.31 bldc firmware (VESC) added “Acceleration Temperature Decrease” option. [ l_temp_accel_dec ]

Vesc Tool describes it thus:

Decrease the motor and MOSFET temperature limits by this amount during acceleration. This is useful to still have braking torque left when the components get warm. A decrease of 0 % means that the acceleration temperature limits are the same as the braking temperature limits, and a decrease of 100 % means that the acceleration temperature limits are at 25 °C.

Huh? … at least that’s how I thought of it at first.

It means that for acceleration the mosfet/motor temperatures cutoffs for start and end are scaled lower than the values you see in the UI. but for deceleration it uses the values in the UI. if you set “Acceleration Temperature Decrease” to 0% then it will use the same values. if you set it to 100%. it will scale the accel temperatures down to 25c.

I made a visualizer so you can play with the values and see the effects on throttling. it’s in desmos a graphing calculator tool. you can move the sliders on the left or drag the points on the graph

Here’s the link to the visualization: https://www.desmos.com/calculator/qfnzuweiys

Here’s what default settings look like with default vesc values:

Here’s what it looks like with 0% Accel Decrease.

And here’s what it looksl like with 100% Accel Decrease

And something in between

those pics are probably enough for you to get he gist. but feel free to play with it yourself. and let me know if you found it useful or interesting.

Changelog that introduced this feature:

vedderb/bldc/blob/80fffde/CHANGELOG#L303-L304

My initial post in n00b questions. but after @taz referenced it I thought it better it have it’s own topic for easier reference.

Archived: the OG noob question thread!

ok i set my acceleration decrease to 0 and start at 90 and stop at 120 and my motors at 50 a as a pair it wasnt bad at all i liked it the worse end i was gettin throtled about 37 kmh Id like to bump it up just a tad bit on the bottom end should i change it to start at 95 ? from 90 again thank all the many people thay went into helping get my bored back to snuff as i feel like its made me a better man (as funny as that sounds)

[ziploc]

Good stuff here. Thanks!

Question (if I may ask it here?)…

My CFOC2’s (VESCs) act very much like they’re slowing down and then stopping due to overheating. But I’m plotting both my motor and FET temps, and I don’t see them reaching the cut-off values I set. Is there somewhere else that would be cutting them out that I just haven’t found?

Thanks.

[fessyfoo]

motor temps can often be noisy, and jump in and out of the range. are you plotting high enough resoution to see this? or zooming in enough? usually shows on zoomed in metr, robogotchi, yours truly, logs.

I assume you’re on this thread so noting this: this setting for acceleration temperature decrease makes the decrease happen earlier than the cutoffs (on acceleration) so. make sure that’s not tricking you.

last, the voltage cutoffs do a similar fade out of power, is your battery voltage sagging under load or at end of charge?

[ziploc]

Thanks very much for the response. I am aware of the acceleration adjustment, and it doesn’t appear like it gets me into the danger zone. I’m logging the data with my own app at 1 sample/sec. If feels like the problem comes on over a period of 10-20 seconds as I’m climbing a hill. So I would think I should see that here.

I’m not running any voltage cut-offs. Instead I have alarms that monitor each cell and beep at me when any cell hits cut-off voltage.

[fessyfoo]

yah those temps don’t look noisy or very high. i think your problem lies elsewhere.