Xiaomi m365 mega upgrade

I was mostly able to answer the question about brake button by 'buying' the config tool. (Will actually donate some money later)

I can use the ADC no problem. But how it works is still not quite clear to me.

When I select "Current No Reverse Brake Button" When does it brake? When I let go of gas AND when I press the brake button? Or only when pressing the brake button?

And of course the question remains, can I switch control regimes at runtime? (Between Current and PID Speed)

And in PID speed mode, is the set point always the ADC value? I would like a cruise control button that keeps the vehicle at the current speed until I touch brake or gas again.

It seems like I will have to think hard about a custom control APP I suppose...

I just realised that my whole assumption that I need the current control type might be wrong.

Is this whole "let go of gas to brake" behavior modern EV have perhaps already just a speed control loop?

I always assumed that would feel weird. But does it? Sorry if I thought it was more complicated than it is.

Ok, this exists. http://vedder.se/2015/10/communicating-with-the-vesc-using-uart/

Therefore all my questions about comms are answered. Though I still would prefer CAN for simplicity. I will investigate...

Oh, and another road-block. The battery I was thinking of getting (which will fir mechanically) is labeled 60V. Which is awfully close to the max voltage rating.

But it turns out, the max voltage is much higher. It's a 16s pack with 67.2V max voltage. That voltage will drop soon. But the electronics must be able to survive it!

So, how hard is that 60V limit? At what are the caps and MOSFET rated?

Thanks, good to know. I would have been tempted to risk a little overspeccing.

Oh, dang. I was hoping I could at least go 14s. I have to work with the motors I got.

The powertrain is designed for 10S and performance is not exactly exciting. Almost no point upgrading if I only get 2-3S plus out of it. :/

It would be plenty strong and fast. But not the beast I was hoping to get.

I haven't actually seen any higher specced VESC out there. Do you have a hint where to look?

As for BMS. Seen that. I love it. But is it possible to get it as hardware anywhere?

I don't have the time and patience to solder it myself to be honest.

I have been wondering. If the only reason for over-voltage situations are transients and inappropriate brake events, should that not be easy to snuff out with a crowbar circuit?

Use a very high power FET and maybe a load resistor. And you turned this into a simple thermal management issue.

Hey fantastic. Keep me updated please. Did you also address the voltage limit of the  DRV8302 chip? I'm actually less concerned about the FETs itself. They tend to be quite robust.But the DRV seems to be very sensitive.  How did you address this?

I will have to measure the battery bay. I think it will fit. Worst case a little diagonal.
18650 cells are 65mm long. From the pictures I have seen there seems to be some space.

Let me find out exactly...

BTW. I suppose you already know this type of modification to the m365?

http://100kilowat.ru/product-category/xiaomi/%d1%82%d1%8e%d0%bd%d0%b8%d0...

This gives you a few mm more debth, which allows you to add a bigger pack (three rows of 18650 in staggered honey comb configuration)

Fantastic. Interesting layout. I suppose the idea is to place that in the hub motor directly?

If you ever need a tester...

I can solder the boards even...

Can I follow your progress somewhere? Github, forum or whatever.

So quick update. I need your help, I'm stuck.

First of all, pretty much everything seems to work great. Motor parameters get detected and it runs smooth and silent.

But in practice I'm very confused with the Amps rating.

Other people have experimented with the motor and 17A is generally considered ot be a safe max power rating. That results in over 500W at 10S and should be plenty. (Roughly twice overclocked related to stock)

But the driving is horrible, unless I effectively knock off all current limits by increasing them to unrealistic values.
Anything under 20A is barely drivable. If I pull the gas, it shows tremendous torque for a split second. But then crashes to zero. I suspect that is a current limiting effect?

If I accelerate very gently, it accelerates very limp and weak but it's somewhat drivable. The PID Speed loop is undrivable because it slams against the limit immediately.

So what is happening? Is Motor-Amps something else than I think it is? Are those currents indeed flowing but don't get turned into power?
I'm a bit lost. I can't just leave the current limit at 60A. Because that is overwrdiving the engine by nearly tenfold.

But then there is the ussue of peak current and sustained current. I don't mind massively overdriving the engine with peak currents in way excess of it's capability. It's just the sustained current that needs to be reasonable. Is there a setting for max and sustained current limits?

Should I look  into the motor wattage tab? Does that limit more reasonable?

It's hard to experimentally determine those settings while spinning wheelies on my wooden living room floor. :)

Sorry I should have clarified. Yes I was using PID mode first, but since that slammed me right into current limits I changed to current mode.

It's still totally unusable. Performance is very low and any sudden accelerations make it disengage immediately (which is I probably some kind of hard current limit condition. I don't know what it is.)

PS: Is threa way to collect telemetry without a cable? I would like to see what's actually happening while I drive?

> What VESC are you running?

Vesc 6

>What control mode (FOC or BLDC)?

FOC so far. But I need to test with BLDC this weekend.

> How long are your cables between battery and VESC, and what's their area?

Laughably thin and quite long. This is why  I want to play it safe with the currents. (Stock harness)

> What is your configured LVC (low voltage cutoff)?

Whatever the wizzard suggested. I can keep a eye on the voltages next test.

> Have you tried reducing the motor current limit to what the motor is specified to handle

That is where I started. It's very weak and unusable. Makes no sense to me to lower the current. The more I give it the better it drives.

> Maybe you're running into the same issue as several others here, with the motor saturating so that the observer can no longer track the rotor?

Can you explain? I don't know what it is I'm running into here. Current limit is just my first intuition, since it goes away if I bump the currents.

BTW, the motor has HAL sensors.

Ah sorry, I misunderstood your question. The battery wires are nice and thick and short. No noticeable drop there. (Cutoff is at 31V. VBatt currently around 39V)

The motor wires are a bit dinky.

I ran some more tests.

The voltage doesn't drop much at all. That's not it.

In FOC mode with 20A I can easily grab the motor ans stall it. Really not much power at all.

I made a screenshot of the live data

In that graph, what is motor current and current in? How can they not be the same? I kind of suspect that my error is there.

Motor current vs. Battery current. How do they relate?

I did some quick test in BLDC mode. It seems a tiny bit stronger. But it reacts badly to being stalled. Current values are all over the place. Feels very rough and dirty.

I did not go any deeper, since it still develops implausibly low power.

Yea, that was the knot in my head.

Of course once you think about it, it makes sense.

I just assumed battery current is 3xmotor current and never reflected on it.

I can report, I'm back to about stock performance. Great success.

Now I can play with the knobs to tickle out the last bit to make it nicer.

And I need to spend some time to understand the ADC input app. Perhaps I don't need to drive the whole thing via can...

I limited motor amps. But what I should have limited was battery amps.

Ii thought I would find it easy, but  can you guys help me with a few hints?

Where is that Cruise Control button? (Same pin as reverse)

Next thing I need to play around with is analog brake. I'm pretty sure I got a hall sensor brake here. That should actually give me a nice proportional signal.

Then I can already see that I need to modify the logic of the cruise control button. I need it latching. If I have to keep my finger on the button, there is no point to it.

I think I figured it out.

Snipped from app.c

case APP_ADC:
        app_adc_start(true);
        break;

    case APP_UART:
        hw_stop_i2c();
        app_uartcomm_start();
        break;

    case APP_PPM_UART:
        hw_stop_i2c();
        app_ppm_start();
        app_uartcomm_start();
        break;

    case APP_ADC_UART:
        hw_stop_i2c();
        app_adc_start(false);
        app_uartcomm_start();
        break;

That boolean for app_adc() defines if rx_tx are used as buttons.

void app_adc_start(bool use_rx_tx);

Ergo, if I don't enable UART I can use the rx_tx pins which are conveniently located.

Since I will be using can to communicate, that works for me.

Successful longer test drive today. ( Had to visit the customs office on the other side of town to pick up some china gadgets  )

I haven't hooked up cruise control yet. Still a little unclear how.

Brake is on ADC2. The analog response is still a bit janky. The mechanical brake grips before it brakes electrically. Perhaps I need some negative expo on the curve.

No Off-Swich yet. No priority for me yet.

I noticed that the motor seemed to pull on for a few seconds after I go off the gas. Either this just feels unusual because it's coasting and not braking. Or there is some kind of cruise control like thing happening from time to time.

Also I notice the current limit still seems a bit restrictive. I will give it more. I'm sure it can take it.

I don't know. I herd that up to 15-20 A are safe.  But that was measured at the battery and with higher voltage.

I have set it to 15A and it was weaker the original  on 10S. I have to experiment more. But I don't think it will be a huge factor unless I'm careless about stalling the engine or going higher voltage.

The improvement on stock 10S wasn't very extreme except for the higher top speed and harder acceleration.

There are alternative firmwares out there which offer ver strong performance on original hardware. If performance is what you are after that is what I would do. Results are great. Potentially even better than with VESC, and you don't loose al the nice bluetooth and battery management features.

I'm thinking bigger. :)

Progress. 12s4p Samsung 30Q pack (3000mAh-15A per cell) with TinyBMS

As you introduced yourself with Moin Moin, there is a chance you speak German.

There is a rather active firmware modding community. Mostly organised in Telegram groups. http://de.m365.wikia.com/wiki/Telegram_Gruppen
Firmware details http://de.m365.wikia.com/wiki/Firmware

If you don't speak German, I think you can still make out the relevant links. ;)

Yes, with the older models you have to be careful with tuning. But there is still some room for improvements for you.

If you plan to tay on the original pack, there is no reason to do anything else than firmware hacking on the scooter.

The people in those Telegram groups can help you identify which battery type you have and help you selecting the right firmware modification that works with it.

Follow up, here you can build your own custom patched firmware. https://m365.botox.bz/

Happy hacking