So I know a lot of you have your opinions about Devin. Love or hate the guy, the formulas he has come up with, whether correct or not, tend to yield positive results. I have yet hear anyone try his formulas, and complain that they had bad settings.
Maybe gearing has an effect? IDK, I have only tried these formulas with hub motors (hummies and carvons), both with amazing results.
The idea is to create a constant wattage at all rpm. This gives a predictable (smooth) acceleration and braking, while increasing low rpm torque in many situations.
Now, you could run the firmware by @Ackmaniac, which implements watt control. Result’s might be even better then this formula, but you do need to change your firmware, which if done incorrectly, could fry your VESC.
For the faint of heart or those looking for a simple solution, this calculator should yield interesting results. Here’s the calculator.
Just an FYI, I am not affiliated with Devin in any way, and have posted this out of my desire to help others, and not at the request of Devin. This was my idea to create, and I was not influenced by anyone but myself into creating it. Please do not argue about Devin here.
Please post your results! The hope is either to confirm or debunk his formulas.
*** WARNING: USE AT YOUR OWN RISK! WE ARE NOT RESPONSIBLE FOR ANY DAMAGE TO YOUR VESC OR MOTORS BY USING THESE FORMULAS! KNOW THE WATTAGE LIMITS OF YOUR MOTOR OR YOU WILL FRY YOUR MOTOR (THIS FORMULA DOES NOT KNOW THE LIMIT OF YOUR MOTOR). KNOW THE MAX BATTERY REGEN AMPS YOUR CELLS CAN DO OR YOU WILL DESTROY YOUR BATTERY! YOU HAVE BEEN WARNED! ***
Just curious, why do you suggest people change their min/max voltage, not sure what the benefit of this is and it may mislead people about needing to set it. I always see newbies adjust this to their batteries voltage, then wonder why they’re board shuts off when they brake.
Also, I tried li-ion 10s4p with .08 resistance, 8 motor min, and 3200w and I get this
Weird… could you highlight the upper left corner of your screen and sedn me the error? It’s a php error, that I am not getting when trying your settings.
For the battery settings, I am just giving advice of new users in case they need advice on what settings to set. These are generic, and not perfect, but they will protect your batteries. Since I have the data I need already, I figure why not…
Highlight the upper right corner, there is an error… You can’t see it cause its black font on black background. But if you click above the home and drag up to the top of the page, you’ll see the error.
You might want to throw in some kind of limiter for the code for li-ion users since 18650’s are typically limited to 20A/cell max. Putting 50 motor min spat out -43A battery min (regen)… lol
Also, when putting .08 resistance, it gives me a notice that the resistance is .16 (2x)
Shit, that’s wrong, it should be a battery min your putting in, not motor min. Need to fix the label. The instructions are correct, and it calculates it correctly, just wrong label.
From what Devin told me, when you measure the resistance in the FOC detection, it’s half of what the real resistance is (the firmware multiples the FOC number by 2 when using it, but stores it at half of the real resistance).
Yes, it’s all on the same formula. Until yesterday, I had never tried to apply it to motor min before. Using the battery min multiplied by the voltage at 2/3rds of the voltage range (assuming that’s about average, will give slightly better performance at higher voltage, which is more likely I think for most people). That gives us a wattage, which can then be used in the other formula, to back track the motor min.
Tried with hummies and the carvons (both 2wd drive, since the each have a broken motor), and brakes are buttery smooth.
I will add a warning about using too high for li-ion packs. Thanks for the advice!
God no. Even if you have a bms, you don’t want to rely on your bms to stop you from over discharging, because theres no cutoff strategy like the VESC has. This means your bms can (and its happened to people before) through you off your board at speed. You want a gradual loss of power that forces you to slow down, not an immediate ejection.
