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Software speed limit consequences?


ir_fuel
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Question, as I don't want to be the one to try it :) 

Right now I have limited the speed of my V8 to 25 km/h. Once I reach that speed the pedals go in tilt-back and I get warning beeps. I know this device is capable of going faster, so what will happen if I ignore this warning and just push through to get over 25 km/h? Will it tilt-back so far that I fall off? Will it cut out?

 

 

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I did that with the ninebot, set it to 10kmh and tested the tiltback.  The faster the acceleration the harder the tiltback.  Didn't really push it though, acceleration wise, just trying to get the feel of tiltback.  It will be interesting to see what the V8 does in your experiment.:popcorn:  I never reach tiltback with the speed limiter off, too scared to get tiltback at 15mph+.  I know the V8 will do about 19.5 mph.:o

Edited by steve454
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Initial results: at both 10kph and 20kph the V8 will tilt back to the point of throwing you off backwards. I wasn't as daring at 20kph but at 10kph I'm sure I hit 29 degrees at one point. It is simply impossible to ride through it to higher speeds. I logged the test and will post the speed/tilt graphs when I get chance.

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Thanks :) 

I had it once with the speed limit at 25 that I accelerated and wow did those pedals move upwards quickly ...

Anyway, set the limit to 30km/h yesterday on mine. Now we're talking. Cruising at 27/28 km/h on paved roads is great!

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On 8/24/2017 at 7:54 PM, WARPed1701D said:

Any wheel should keep speeding up to the point of 0 torque when it can do no more and then you overlean and eat dirt.

You are missing out the observation that if we lift the wheel off the ground it does shut off, and to do this reliably it must do so before (exactly) zero torque is reached.

Obviously at high speed we usually do not reach anything close to 0 torque, because even keeping up the speed needs considerably torque. But then, when the street slope is downwards, we could get in exactly this situation.

Edited by Mono
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  • 9 months later...

Guys thanks for the very useful posts on this.

I have a related question so I didn't want to create a new topic for it.

Should I have any concerns with setting the software speed limit on my V8 to 30 km/h? I currently have it set at 28 km/h just to make sure I don't overburden the motor.

The downside with this setting though, is that I frequently get a tilt back as I tend to remain as close as possible to the the top speed while cruising.

Now I want to set it to 30 km/h but I wanted to ask here to see whether there is a strong argument for not doing so (negative impact to battery life, over-heating, etc.) With respect to the tilt back, I guess I will still have the issue as I will simply try to go faster than 30 km/h this time. So that's not a huge concern at this moment.

Thanks in advance for any responses!

Edited by Moshtrat
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What's the point to squeeze out 2km/h when you expect to fully ride into the tiltback anyway?

The concern I have is neither motor problems nor overheat but riding closer to the torque limits and at higher speeds, which increases the likelihood and the severity of a crash.

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Thanks for the feedback. Well, I guess after a while I will learn to feel the slightest tiltback angle and therefore avoid the alarm sound by keeping a constant speed around 29.x km/h.

I see it from the other way around. Why reduce 2 km/h unless it has a clear advantage from a safety / battery lifetime / engine durability / etc. perspective?

A crash at 27.x km/h would not be so drastically different than a crash at 29.x km/h by the way.

Anyway, I will still keep the current setting at 28 km/h for a while, until someone can provide a convincing argument that it's no problem to increase it. Better safe than sorry. : )

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Thank you @Keith for this excellent input. I will go by your advice and try absolutely not to have any tiltback. I'm sure I can get the feel of it soon.

Although, apart from the available torque and the probability of a crash,  I must admit that I still don't have an idea whether this would have a negative impact on overall battery life. This is quite important for me as I need at least a 20 km autonomy per charge (a round-trip to work) for my EUC to be a viable alternative to my car. Currently, I have 30% battery left after the round-trip and I want it to remain like this for (let's say) another two years after which I don't mind investing in a new EUC or a new battery.

Thanks also to all others for the interesting discussion.

 

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6 hours ago, Moshtrat said:

I must admit that I still don't have an idea whether this would have a negative impact on overall battery life.

Speed certainly does consume more battery really, I suspect, mostly due to the increased wind resistance so you may well find similar impacts at slower speeds on days you are riding into a strong wind (although unless unlucky the tailwind going home should compensate.)

As for battery life. Leaving it fully charged for long periods and draining it regularly below 20% will have the most significant impacts on battery life, but the latter shouldn’t be that  significant in two years. You would have to try doing a run at higher speed and see what battery that leaves you with - if it is below 20% then I would say that was too much.

The other issue, given where you are is cold, in sub zero temperatures battery capacity can temporarily REALLY drop, if you have 30% left at this time of year then you had better start thinking of taking the charger to work in the winter or at least keeping the wheel nice and warm whilst at work and at home. Also do not forget that 0% according to the wheel isn’t 0% in reality. The software will have a safety margin that could in itself be up to about 20% capacity.

An interesting discussion with a somewhat more extreme example of going fast on a Tesla below, gives an idea how much range can reduce at high speed.

 

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On 5/31/2018 at 7:10 PM, Moshtrat said:

A crash at 27.x km/h would not be so drastically different than a crash at 29.x km/h by the way.

15% more impact on your bones to crack in exchange to 7% of increased speed or saved time. At this speed, 15% is IMHO already pretty significant.

Edited by Mono
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On 6/2/2018 at 1:01 PM, Mono said:

15% more impact on your bones to crack in exchange to 7% of increased speed or saved time. At this speed, 15% is IMHO already pretty significant.

Thanks for the data. There must be a whole lot of physics behind it.

15% more impact on your bones to crack 'when you fall' in exchange to 7% increased speed or saved time 'everyday'. IMHO, it's all about risk management as everything else in life. : )

I will see with the battery figures. This morning my phone was out of charge so I couldn't record the trip. Just had two tilt backs for the entire half-hour journey though. (Which was more around 25 minutes today though I was lucky with the traffic lights.

Also thanks @Keith for the very useful additional insight.

Cheers!

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On 6/2/2018 at 2:01 PM, Mono said:

15% more impact on your bones to crack in exchange to 7% of increased speed or saved time. At this speed, 15% is IMHO already pretty significant.

Are we talking about falling to the ground or riding into a wall?

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4 hours ago, mrelwood said:

Are we talking about falling to the ground or riding into a wall?

Right, the distance from your head to the ground is relatively constant, although your available time to react is going to be reduced as the speed increases. The major risk I've had in falls is hitting the ground and having my body parts ground away by asphalt and concrete. That's one of the big benefits of helmets and wrist guards. You actually want them to be relatively smooth so you'll slide along the ground and slowly lose the speed rather than ending in a sudden stop that stresses body parts. Learning how to roll is another way to lose the speed but I haven't had luck reacting quickly enough when going more than 10mph.

In my most recent injury I was taking a corner and hit a bump. So unlike a forward faceplant, I sort of came off the EUC sideways and my foot struck the ground while I still had quite a bit of lateral speed from the corner. My knee didn't like that and I tore several ligaments that are still healing. I would have been better off if my foot hadn't landed on the ground where it could get traction!

At this point I'm over the whole max speed thing. Most of the time I'm riding in areas where 15mph is pretty fast, there's no need to push it harder. 

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On 6/4/2018 at 5:23 PM, mrelwood said:

Are we talking about falling to the ground or riding into a wall?

For riding into a wall my hunch is that it wouldn't matter anyways.

Edited by Mono
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On 5/31/2018 at 11:17 AM, Moshtrat said:

Guys thanks for the very useful posts on this.

I have a related question so I didn't want to create a new topic for it.

Should I have any concerns with setting the software speed limit on my V8 to 30 km/h? I currently have it set at 28 km/h just to make sure I don't overburden the motor.

The downside with this setting though, is that I frequently get a tilt back as I tend to remain as close as possible to the the top speed while cruising.

Now I want to set it to 30 km/h but I wanted to ask here to see whether there is a strong argument for not doing so (negative impact to battery life, over-heating, etc.) With respect to the tilt back, I guess I will still have the issue as I will simply try to go faster than 30 km/h this time. So that's not a huge concern at this moment.

Thanks in advance for any responses!

I did this.

It's dangerous.

Once you get used to the wheel (or I was used to the wheel) I was constantly riding it at around 28 km/h. At that speed even small bumps in the roads (the edge of a repaved part for instance) could trigger a warning sound. And then I hit a bigger ledge at that speed .... cut out and air time was the result. And some bad injuries.

IMO it's not a safe wheel to ride constantly above 25 km/h. There is just too little margin left.

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  • 2 months later...
On 6/5/2018 at 9:57 PM, ir_fuel said:

I did this.

It's dangerous.

Once you get used to the wheel (or I was used to the wheel) I was constantly riding it at around 28 km/h. At that speed even small bumps in the roads (the edge of a repaved part for instance) could trigger a warning sound. And then I hit a bigger ledge at that speed .... cut out and air time was the result. And some bad injuries.

IMO it's not a safe wheel to ride constantly above 25 km/h. There is just too little margin left.

I'm sorry I took my time in getting back to this topic. So now let's provide some post-incident feedback.

@ir_fuel, I basically lived through every single word of what you wrote there. :P I guess I had to learn it through first-hand experience though.

Speed limit set at 30 km/h, constantly riding the V8 at around 28 km/h for three weeks (20 km total commute per weekday), and one evening I hit that bigger ledge (thanks to a deeper than normal gutter right before an otherwise gentle curb)... cut out and air time. I was very very lucky to fly into a roll on my right shoulder and simply bounded back up and gathered the tumbling wheel following behind. No visible bruises, but I had pain on my shoulder for more than a month (still not fully healed).

Lesson learned, I now have the speed limit set to 27 km/h and consistently ride at around 24 km/h with much more attention to curbs and ledges.

In the end, battery life/performance needs to be a much lower concern than safety. I usually go down to 30% with a return commute and then charge it during the day. I will update here once this gets worse.

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If I can add me 2 cents here too. And please please correct me if I am wrong.

As I understand it there are a few things that can trigger a cut out.

Riding at top speed increase the risk, but we get back to this later.

Wheneverthe wheel try to balance it requires power. As the moter perform at max then it leaves no root to cope with the demand to let's say climb an edge. Performing at max can be on flats e.g. at top speed but as you climb a hill speed you can achieve will be lower. On downhill it is resistance the wheel provide that is important. As you add more weight from the rider this can shift what demand the wheel have free to reach a "rated top speed". 

Moving from the motors capability to where do the power come from. This can be a bottle neck that limits the power of the motor too. Due to Inmotion V8s battery it can only deliver that much and the cabling adds to the limit too. Compared with a dual pack battery as it can load share the need of amps. 

This translate to comparison with my Kingsong KS18L that the motor have more power, the battery can deliver more amps and the bigger rim helps to climb curbs and edges easier as it do not need the same power spike to balance over the edge. 

Now as emergency breaking or downhill speed limiting hold aka effectively breaking it is important to know wheel act as a dynamo storeing break energy into electricity in batteries. If the breaking cannot discharge into battery then you will likely experience a cut off from the wheel.

Now back to top speed. This is part reason why I upgraded from V8 to KS18L. I wanted better safety margins and longer distance. I have limited the wheel tiltback at 40 kmh in app it is similar to 35ish real kmh though. But the head room I have is much bigger. Which also means I can ride longer at 30kmh with less risk of cut out and long on the charge as the battery powers is tapped out as I do not ride at edge.

And this is why I have a big fat smile on my face as I worry less but still keep focus on what I am doing. I am cruising not racing. Most of the time in traffic I have no control over, so I need to stay prepared.

You need to respect the wheel, the surroundings and keep in mind speed it not a friend once it starts going tits up as they say in the UK.

Sorry for a long post, but I hope some new riders find this useful reading. No need to walk about in pain for months if you just understand what happens with a wheel between your feets. Wheel and riding dynamics are things you need to know to avoid pain.

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