Making Begode wheels safer: PWM tiltback with custom firmware

[redfoxdude]

2 hours ago, Freestyler said:

I'm happy to report that the PWM tiltback has been ported to all wheels. (apart from hero c38 firmware which is not released yet)

It needs testing on ex20s & hero, because I'm not sure how it will behave if the wheel is configured to use miles instead of kilometers.

Also on master which is the only wheel where PWM is not hardcoded, but rather taken from the adjustable PWM feature of the latest firmware.

Very exciting! Re: the adjustable PWM feature - are they letting users configure the stock PWM alarm? Anyhow, I'm interested in testing on my Master - super keen on the dynamic tiltback and would be happy to contribute.

Edited July 13, 2022 by redfoxdude

[Freestyler]

Yeap, it's already supported in euc-dash but needs testing.

 

I would love for you to try the firmware. I will send you a pm!

[daniel1234]

Awesome guys ! I need to give it a try at mine master - But it is hard to ride at more than 80 procent PWM there . I think tiltlback is much better than beeper.

Edited July 14, 2022 by daniel1234

[alcatraz]

On 7/14/2022 at 5:20 PM, daniel1234 said:

Awesome guys ! I need to give it a try at mine master - But it is hard to ride at more than 80 procent PWM there . I think tiltlback is much better than beeper.

The skidmarks in the underpants warn way WAY before 80%.

[Freestyler]

Heh. Yeah, if one does not exceed 60% PWM, then PWM tiltback is not really needed. A fixed tiltback speed would do the same job.

 

Example: Take a wheel that beeps at 60km/h with 100% battery.

at 10% battery the speed is reduced by 20%, so that's 48km/h. (not sure if this still holds true for the newest firmwares that discharge the cells lower).

 

If you never go more than 48km/h, then you can set the tiltback at 46-48km/h and be done with it for the whole battery range.

The PWM tiltback makes sense for people wanting to squeeze more than 60% from their wheel, but still have a sensible limit.

Edited July 15, 2022 by Freestyler

[supercurio]

@Freestyler there is one type of alert which is missing on Begode / Veteran wheels compared to Kingsong and Inmotion: phase current alarm.

At the moment, if your lean to brake or accelerate, at a speed which is too low to reach 100% PWM, and it leads to phase current very close to the 220A, 240A etc (depending on model) limit, nothing alerts you. And you can dip forward, overlean the wheel and crash - same during hard braking.

Therefore I'd like to suggest a new firmware feature if feasible: alarm on 80% max phase current!
I've always been surprised it is missing from stock firmwares. It's mostly useful when accelerating hard and climbing, in order to avoid falling forward by asking too much.
I'm saying 80% here, but it might be some other % to be practical, depending on the rider weight and possibly varying with the current speed.

With both PWM + phase current alarms, I think it will cover most of the wheels power limits.
I plan to implement that in EUC Alarm app but the latency will be lower in firmware, making it significantly more effective since that one is very delay sensitive.

Edited July 15, 2022 by supercurio

[Freestyler]

It's something that has been bothering me as well, but I simply lack the knowledge to understand it.

We now have a very good warning system to prevent against overspeed cutoffs, but we still don't know the overtorque / acceleration limits.

For example: How fast I can accelerate to 50km/h on a wheel that can do 60km/h (even at 10% battery)?

Let's say a wheel has 250a phase current limit. We now know how much headroom we have when we do crazy leans at low speeds, but as the speed increases so does the back EMF from the motor. (which cancels the battery supplied voltage)

You can't push 250a when going 40km/h. So how much current can you push at each speed? What is the formula?

You need information such as the motor kv and winding resistance. Maybe PWM information is useful here. Can you help @Chriull?

If we know the max current for each speed (or PWM), then we can set an alarm in a fixed percentage.

 

Btw the latency of the app is not higher if any at all, because to sound the beep a timer is used internally and you might be in an unfavorable time window relative to the interval.

That's why sometimes you see the alarm state in packets faster than hearing the beeps. Euc alarm has very good latency as well.

I think the very nature of extreme leans is that even with alarms it's not guaranteed to save you. If you are in an extreme lean position and hear the beeps at 80% of max current, you might not have enough time to react.

Still it would be immensely useful to slowly learn the acceleration limits of your wheel, because as it is right now we are completely blind.

Edited July 15, 2022 by Freestyler

[psEUCdonym]

Hi @Freestyler I have connected my Commander C38 HT to EUC DASH, and I got the model code. Is it possible to flash my wheel with the custom firmware?

[Freestyler]

Unfortunately Extreme bull firmwares have not be released (commander & x-max)

Commander also lacks a lift switch button from what I see, so recovering a bricked wheel will be more involved.

[psEUCdonym]

4 minutes ago, Freestyler said:

Unfortunately Extreme bull firmwares have not be released (commander & x-max)

Commander also lacks a lift switch button from what I see, so recovering a bricked wheel will be more involved.

So sad, thank you!

Edited July 15, 2022 by Mauricio

[EMA]

1 hour ago, Mauricio said:

Hi @Freestyler I have connected my Commander C38 HT to EUC DASH, and I got the model code. Is it possible to flash my wheel with the custom firmware?

i have the c30, your pedals rise when you reach 50kmh or more ? 

i'm asking becouse the first time i rode the wheel i didn't have this feeling, yestarday i had it. seems like "accelerated stability" ...or maybe a tiltback setting that not works

[psEUCdonym]

On 7/15/2022 at 9:02 AM, EMA said:

i have the c30, your pedals rise when you reach 50kmh or more ? 

i'm asking becouse the first time i rode the wheel i didn't have this feeling, yestarday i had it. seems like "accelerated stability" ...or maybe a tiltback setting that not works

Hi, I have the HT C38, And I have not experienced that, I ride in medium mode.

[tupercav]

On 7/10/2022 at 2:46 PM, Freestyler said:

Sure it can! Connect to euc-dash, send me you model code and I will reply with instructions to flash.

Hello, i would also like to try this on nikola 100v with custom 3000 battery.

My nikola is 1702001

[Leskont]

Hi, now I'm ready to try this firmware on the Tesla T3. Model: T3, Model code: 1601001

I also want to try it on MSM5 later. There I have a custom battery on Samsung 40T high-current cells. And I was interested in the battery percentage scale in euc-dash. Is it possible to correct it in your firmware? The fact is that 40T can be discharged deeper than stock Begode

[Freestyler]

You mean lower voltage? If so, I don't think this is the case. 3.3v is the tiltback voltage for MCM5 and looking at graphs for the sanyo 18650ga & Samsung 40t, I don't see why they would handle lower voltage. Did you mean higher discharge?

 

I've sent you a PM for the firmware.

[Leskont]

Below I have attached graphs.
The stock NCR18650B D has a voltage drawdown of about 0.5 volts at a load of 10A.
The Samsung 40T, even with a higher load of 12A (blue line), has a voltage drawdown of only 0.2-0.3 volts.

Therefore, in Begode stock batteries it is safe to set the lower threshold of the cell voltage at 3.3 volts, since this leaves a margin for drawdown until the battery is fully discharged at 2.5v. (0.8v difference)
But at 40T it is redundant. In this case, it is safe to put the discharge at 3v, leaving a margin of 0.5v difference for voltage drop

So we will increase the useful capacity to +30% (judging by the same graph) 

 

PS: Thanks for the firmware, I will try)))

[Freestyler]

Don't the wheel use sanyo ga cells which should be a bit better than the b variant?

Are you running a 2p setup is is there room for 3p 21700?

I can prepare a firmware with lower discharge for you to try. (60v)

Edited July 22, 2022 by Freestyler

[alcatraz]

This might be offtopic but shouldn't the lower voltage limit come with an extremely low pwm limit for that charge range. Like you just look at the wheel, and it tilts back.

[alcatraz]

Then you could technically ride it down into 2.x V but would anyone ride with that weak of a wheel?

Also, do we really expect a pack that is TOP-balancing groups to arrive to such low voltages at the same time? Likely you'll have one group arrive there first and as the wheel thinks you're at 3.0v average and accelerate, you're bringing that first group below 2.5v.

[Leskont]

23 minutes ago, Freestyler said:

Don't the wheel use sanyo ga cells which should be a bit better than the b variant?

Are you running a 2p setup is is there room for 3p 21700?

I can prepare a firmware with lower discharge for you to try. (60v)

I just looked at what I have written on the battery in my MCM5)))
I do not plan to put 3p parallels, since I have enough and 2p for 40T, they give a lot of energy and this is a very cheerful wheel!!! 3p is just not needed there.

Yes, it would be great to try to discharge up to 60 volts on my MCM5.

Edited July 22, 2022 by Leskont

[alcatraz]

The idea might be fun but at 60V it wouldn't be a 1500W MCM5 anymore. It would be a 500W wheel that cuts out by just looking at it. Risky. 

[Leskont]

Lowering the charge below 2.5V is detrimental to the battery. It will simply fail, losing a significant part of the capacity.

20 minutes ago, alcatraz said:

Also, do we really expect a pack that is TOP-balancing groups to arrive to such low voltages at the same time? Likely you'll have one group arrive there first and as the wheel thinks you're at 3.0v average and accelerate, you're bringing that first group below 2.5v.

I use SmartBMS... The difference between the elements is 0.002v

Edited July 22, 2022 by Leskont

[alcatraz]

You need a high current pack to bring down those voltage limits and 2P high current maybe isn't a huge world of difference to 3P high capacity. 

2 minutes ago, Leskont said:

Lowering the charge below 2.5V is detrimental to the battery. It will simply fail, losing a significant part of the capacity.

I use SmartBMS... The difference between the elements is 0.002v

Yeah at 4.20V it's at 0.002. Not at 2.5v

[Leskont]

12 minutes ago, alcatraz said:

The idea might be fun but at 60V it wouldn't be a 1500W MCM5 anymore. It would be a 500W wheel that cuts out by just looking at it. Risky.

If it's a stock battery, yes.
If it's 40T - no!!

I threw off the discharge charts above, and 2p 40T can be discharged with a current of 70A! While the stock is even 3p by default maximum 30A

Edited July 22, 2022 by Leskont

[Leskont]

6 minutes ago, alcatraz said:

Yeah at 4.20V it's at 0.002. Not at 2.5v

I did not look at the difference at a voltage of 2.5v because the wheel does not allow the battery to discharge so deeply, but at 3.6v the difference is 0,002v

Edited July 22, 2022 by Leskont