Making Begode wheels safer: PWM tiltback with custom firmware

[Bizra6ot]

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Just saw @Chriull comment that answers this 

Edited September 2, 2022 by Bizra6ot

[Freestyler]

35 minutes ago, Chriull said:

The real actual value depends on your battery charge state, internal battery resistance, coil resistance, temperature and battery 'burden state".

All of this is already included and regarded in the pwm %...

The only real disagreement we have here is about that.

I'm saying that PWM does not have all the information.

For example @RagingGrandpa in his pull tests, he reached a maximum of 35% PWM until the firmware stopped him (~250a for his msp)

He only reached 100% PWM when his wheel lost traction accidentally and free spinned.

 

So when climbing steep inclines at low speeds, you will never reach high enough PWM values for the alarm to be triggered, but you can still overtorque the wheel.

By placing an alarm at 200a for example, you are still not protected, because at speeds of around 30 km/h, the actual limit might have dropped down to 150a.

 

Anyway, I realize that it's impossible to get this info with so many unknowns.

Maybe the overcurrent status in Master pro will help us understand it better if someone triggers it in different speeds and plot the data to a graph.

But who would be so crazy to do it in the speeds that Master pro can reach? No one 

[Chriull]

1 hour ago, Freestyler said:

I'm saying that PWM does not have all the information.

I'll try to show you in the next days with some graph and an equivalent circuit diagram (there is no nice one in all of my posts)

1 hour ago, Freestyler said:

For example @RagingGrandpa in his pull tests, he reached a maximum of 35% PWM until the firmware stopped him (~250a for his msp)

As this was stall torque. As with low speed were furmware cuts off intentionally off before 100% pwm is reached.

The ~250A are choosen to save the mosfets and wires - that's not the torque limit.

Aa written above for this limit one needs seperate handling.

[idemetriss]

On 9/1/2022 at 5:27 PM, Freestyler said:

I'm regularly been mistaken for Freeforester, but first time as Freewheeler!

 

Apologies everyone for being absent. In August no one works in Greece (too busy island hopping ) and then I got covid and was off for a few more days.

I will get slowly get back to everyone that messaged me, thanks for being patient!

Hi.

I would like to try your firmware, but cannot send the messages yet.

How to contact you then?

[Chriull]

With the "Inverter Formula" U Battery * I Battery = U Motor * I Motor (lossless inverter) and U Back EMF = speed / kv the whole (simplified) Motor formulas can be derived.

Or like with the a bit more detailed circuit in https://forum.electricunicycle.org/topic/7549-current-demand-versus-battery-voltage/?do=findComment&comment=104078

with the formula set in https://forum.electricunicycle.org/topic/7549-current-demand-versus-battery-voltage/?do=findComment&comment=100560 .

Regarding PWM, max motor current, etc here a graph with a limit line like in the other topic for the logged ride:

Here is the main difference, that the maximum motor current is not shown on the Y axis (but could be) and the no load speed is not shown in km/h (but could be, too).

If one knows the actual U battery no load, the internal battery resistance and coil resistance one knows the maximum current (I=U/R) and with the actual U battery no load and kv one has the no load speed...

By the motor controller regulating the motors in conjunction with the batteries capabilies by pwm ing the mosfets one has at 0% the motor at standstill (0,0) in the diagram up to a pwm of 100%. This 100% mean the mosfets connect all the time - the maximim current from the battery goes to the motor. One has reached the limit line! So U battery no load, internal resistance, coil resistance, temperature, humidity is regarded by just looking at the pwm %.

As shown in the graph for point 2 and point 3 one has at the limit always the part along the x axis of "pwm % consumed by the speed" and the difference to 100% is still possible to be "consumed by the burden"

For Point 1 only 70% PWM can be reached, as the firmware limits the maximum motor current ( in this example at half of the maximum possible current)...

And maybe (some) wheels have some additional stall current limitation for not only low speeds but for about standstill?

In contrast to the simplest equivalent circuit diagrams for li ion cells and the motor limit looking at the torque over speed diagram with pwm % considers even all side and what not effects happening in reality - like the next refined step for li ion cell modelling as described in http://rincon-mora.gatech.edu/publicat/jrnls/tec05_batt_mdl.pdf  or more sophisticated models for motor limits.

Regarding the "dynamic limit":

Here the diagram from above again with the blue dotted line showing the 80% limit and 3 points in time from some riding A, B and C. One knows the timestamps of these points and can extrapolate the line A-B until it reaches the overlean limit (or 80%...) like here shown by the red line. So one knows how long it will take in the acutal situation until one overleans (reaches 80%) and coul initiate tiltback by some threshold. Same for B-C, C-(D), ...

In reality the line is not as nicely smooth but very "noise" from balancing back and forth so the continuation line going wildly around would trigger many alarms...

So some smoothin/averaging/low pass filtering should be applied to the original values.

 

 

Edited September 5, 2022 by Chriull

[Freestyler]

Thanks for taking the time to share your knowledge!

 

If I understand correctly, you propose to add a warning based on the PWM rate of increase?

And is that based on PWM alone or in relation to the speed? eg. different rate of increase for PWM compared to speed.

[Chriull]

3 hours ago, Freestyler said:

Thanks for taking the time to share your knowledge!

You'r welcome.

3 hours ago, Freestyler said:

If I understand correctly, you propose to add a warning based on the PWM rate of increase?

Yes. If it's worth the effort.

3 hours ago, Freestyler said:

And is that based on PWM alone or in relation to the speed? eg. different rate of increase for PWM compared to speed.

No. Just on change rate of pwm.

[RagingGrandpa]

@Mike Sacristan - what was your conclusion overall, after raising the current limit? 

[Mike Sacristan]

11 hours ago, RagingGrandpa said:

@Mike Sacristan - what was your conclusion overall, after raising the current limit? 

It definitely feels stronger. I got on my Nikola afterwards with its measly 200A and if I try to do a burnout and screw it up it will crank right through the motor.

This part in particular is something I have not dared to do before: https://youtu.be/BPyj3iNKupg?t=745 

Although one of my more reckless riding buddies has done it.. on his MSP MSS. Now that I am comfortable with it perhaps I can use it as a comparison with other wheels. Doing a torque test / stall test / pull test would be interesting too! I should check in with François and we could test it. Fingers crossed nothing blows lol.

Elias (MSP HT rider) and I compared battery after the ride and we were both at similar battery despite me riding a bit faster and having less battery (Samsung 40T 1500Wh vs LG M50T 1776Wh). We would need to ride down lower though to do a proper range taste and ride at more equal speed.

But as for power... it's definitely there! I didn't push it hard enough to push through the magnets/motor like I can on some other wheels. So yeah... I will need to make a part two where I can do some more aggressive testing. I just didn't want to kill it in my first clip lol.

 

[Freestyler]

On 9/2/2022 at 8:27 AM, meriwald said:

@Freestyler

I'm impressed with your work, how did you get ahold of firmware, isnt it encrypted stored in the nand?

Do you think it's possible to apply old settings from boards before v14 for rs ht to make it as strong as MSP was? New boards v14 and higher are so sluggish

I missed that post. Firmwares were obtained from the app.

You are the 2nd person who has told me that the older boards were stronger.

So far I have not seen anything that indicates a limitation.

I have heard that the commander has a limit on low speeds, but I don't have a commander firmware to check out.

 

 

For the phase current: 

I believe that it's hard to measure the difference on real conditions because when you are told that you have a stronger wheel, you might lean harder and achieve things that you could also do before but never tried.

So far everyone who has tested a higher phase current limit though, has reported a noticable change, so there must be something there!

Btw the limit can be increased to 255 (maximum 8 bit value), but there is no wheel with a value higher than 250 so far.

Edited September 10, 2022 by Freestyler

[Bizra6ot]

What do the logs show(from the video)?

Could be wrong but for me the gain should be especially effective on the first impulse of a strong acceleration from standstill which allows not to dip as early, but since the extra 30A can be reached in few milliseconds it can save you occasionally but it is not enough to be reproduced on every acceleration reaching exactly between 220 and 250 to feel a difference

Or on a bad landing after a dirt jump since in the air the wheel is like at standstill and it creates a high peak when touching the ground, apart from that it is not a really exploitable gain that makes the wheel stronger in everyday situations

[Freestyler]

On 5/16/2022 at 7:40 PM, Freestyler said:

Next steps

I want to make begode wheels safer for everyone and by flashing few wheels here and there is not scalable.

Ideally we want Youtubers and distributors to pick this up and apply their leverage to Begode, so that wheels ship out of the factory with dynamic tiltback.

An update on that. @Mike Sacristan has helped raised awareness of this mod which in turn made @iCafe the first distributor to pick this up and help push this further.

We had some early talks with Begode about this feature. Fingers crossed that they will implement it themselves by default.

Thanks Mike and Sergei for believing in this!

[yu_duk]

8 hours ago, Freestyler said:

Обновление по этому поводу.@Майк Сакристан помогло повысить осведомленность об этом моде, который, в свою очередь, сделал @iCafe первый дистрибьютор, который подхватил это и помог продвинуть это дальше.

У нас было несколько предварительных переговоров с Begode об этой функции. Скрестим пальцы, что они сами реализуют это по умолчанию.

Спасибо Майку и Сергею за веру в это!

Dear Freestyler, thank you for what you are doing in terms of promoting safety for euc on pwm, the new wheels can and will support your option and what about those who already have an old two year old wheel, Begode even removed them from the update program, we will not get your function?

[meriwald]

On 9/10/2022 at 9:12 AM, Freestyler said:

I missed that post. Firmwares were obtained from the app.

You are the 2nd person who has told me that the older boards were stronger.

So far I have not seen anything that indicates a limitation.

I have heard that the commander has a limit on low speeds, but I don't have a commander firmware to check out.

 

 

For the phase current: 

I believe that it's hard to measure the difference on real conditions because when you are told that you have a stronger wheel, you might lean harder and achieve things that you could also do before but never tried.

So far everyone who has tested a higher phase current limit though, has reported a noticable change, so there must be something there!

Btw the limit can be increased to 255 (maximum 8 bit value), but there is no wheel with a value higher than 250 so far.

Can I contact you in DM regarding flashing my rsht board? It's a real bummer having strong hollow motor wheel all ready for offroad but with lower current limit than previous generation.

Here I'm going down a small drop followed by a nice downhill (drop maybe 4-5m high), my MSP HT wouldn't give me even a one magnet skip, rs ht on this hill clacked and tilt me back so badly, I was barely able to hold a balance, you can see me squatting there 😁

https://www.instagram.com/reel/CiZZDqtNC3r/?igshid=YmMyMTA2M2Y=

Also interesting fact: I'm using additional 4700uF capacitor connected parallel to the battery. It gives a significant difference on MSP and no difference whatsoever on rs boards v14 and higher (so called black boards). So one more sign there is a lower limit for amps.

 

[yu_duk]

1 hour ago, meriwald said:

Здесь я спускаюсь с небольшого обрыва, за которым следует хороший спуск (падение может быть высотой 4-5 м), мой MSP HT не дал бы мне даже одного магнитного прыжка, rs ht на этом холме щелкнул и так сильно наклонил меня назад, Я едва удержал равновесие, вы можете видеть, как я там приседаю 😁

https://www.instagram.com/reel/CiZZDqtNC3r/?igshid=YmMyMTA2M2Y=

Также интересный факт: я использую дополнительный конденсатор на 4700 мкФ, подключенный параллельно аккумулятору. Это дает существенную разницу на MSP и никакой разницы на платах rs v14 и выше (так называемые черные платы). Итак, еще один признак наличия нижнего предела для ампер.

I suffered for a long time and fell several times at low speeds, falling into a hole or during a sharp movement back and forth. I found a way out of this situation by soldering an additional shunt to the v14.2 board, thereby increasing the current by 1.5 times, but this is dangerous for the battery, and indeed, as an output, a capacious additional capacitor. I have a battery from Nissan Life, it digests such currents, but I still think to increase the capacity.

[RagingGrandpa]

6 hours ago, yu_duk said:

soldering an additional shunt to the v14.2 board, thereby increasing the current by 1.5 times,

Haha, as you pointed out, a motor current limiter is not strictly necessary... But I love knowing that my controller will protect itself if the tire gets jammed. I'll keep the limit.

Removing the current limit does not improve high-speed performance. It will not prevent over-speed crashes. Because the system voltage creates the speed limit; not the current.

(And hopefully it was obvious: Don't pull-test controllers that have their limiter defeated! Poof)

[meriwald]

9 hours ago, yu_duk said:

soldering an additional shunt

Do you mean in parallel to r001 resistors? How much did you add ? 

That's a great idea. So there are two options to hack it now: software adjustment and hardware fooling the software that it stikl running on thw preset limit :)) 

[yu_duk]

10 hours ago, meriwald said:

Вы имеете в виду параллельно резисторы r001? Сколько ты добавил? 

Это блестящая идея. Таким образом, есть два варианта взломать его сейчас: настройка программного обеспечения и аппаратный обман программного обеспечения, которое он продолжает работать на заданном лимите :)) 

Yes, I put an additional 0.01 Ohm resistor, I was worried that something would go wrong, but everything is fine, there are no changes in the logic of work, I have already driven 2000 km like this, and it saved me. I do not know how to change the program, and I did not have to. I just soldered one resistor on top of two on the phase wires.

[daniel1234]

2 hours ago, yu_duk said:

Yes, I put an additional 0.01 Ohm resistor, I was worried that something would go wrong, but everything is fine, there are no changes in the logic of work, I have already driven 2000 km like this, and it saved me. I do not know how to change the program, and I did not have to. I just soldered one resistor on top of two on the phase wires.

Please show us some pictures of your monster wheel  !

 

[Timwheel]

I am a bit confused. Here's what I understand/tried (on my master 50E):

- You can set up a fixed speed limit tiltback out of the box with the app (without custom firmware update) higher than what was possible with the begode app: it seems to work with me at least, a tiltback set @70km/h does activate when I freespin it. You can also change pretty much everything else with the app, miles/km conversion, light, roll angle, pedal mode etc...

- You can't set up a PWM dynamic tiltback without flashing a custom firmware on your wheel, even though you can select it in the app. It seems to default to a fixed speed limit then.

 

It is however difficult for me to know, as the master has a top speed in the 100s km/h so I don't know if the tiltback is due to pwm 70% or 70km/h since they should kick-in in the same ballpark.

 

If I understood correctly, I read that there isn't an easy way to mod the fw without Freestyler's help. I just didn't understand how the others got their wheels working with that PWM control.

 

Can someone clarify that for the dumbass that I am ? Thank you very much

[yu_duk]

15 часов назад, daniel1234 сказал:

Пожалуйста, сообщите нам несколько фотографий вашего колеса-монстра 

 

Edited September 13, 2022 by yu_duk
Images

[litewave]

1 hour ago, yu_duk said:

 

 

It looks indestructible and reminiscent of @EUC Extreme's wheels.

What is this?

[yu_duk]

5 hours ago, litewave said:

Что это?

this is a battery, Liion from a Nissan Leaf car, only disassembled;)

[meriwald]

11 hours ago, yu_duk said:

this is a battery, Liion from a Nissan Leaf car, only disassembled;)

Holy shit this is a heavily modified wheel 👍👍😁😁

I would recommend add more solder on all MOSFET's legs. And add extra current jumper across the board, like monster pro and master has, the copper bar.

Any other mods on your wheel?)) That's so amazing ))👍👍

[yu_duk]

4 hours ago, meriwald said:

Есть еще моды на твой руль?)) Это так здорово ))

Except that this wheel is ignited by the ignition of the battery. I had to rewind the large section motor, instead of 4mm2 to 5.5mm2, and re-magnetized magnets, this is the most common Begode RS;) https://forum.electricunicycle.org/topic/30028-how-i-remagnetized-demagnetized-neodymium-magnets/#comment-435977