Inmotion V13 Speculation

[Uras]

or it could be because...

 

Edited January 31, 2023 by Uras

[soulson]

I just did the math on the OG Sherman battery:

50 mOhm cell internal resistance * 24 cells in series / 10 cell stacks in parallel = 120 mOhm battery resistance

The Sherman battery would need to source 100 amps to provide 10kW at 100V. Again following P = I^2*R, we would expect to see 1.2kW wasted as heat in the OG Sherman battery under the peak load stress of a V13 powertrain. By that, we can say that the OG Sherman battery is "2 percentage points" more efficient than the V13 battery (88% efficient vs 86% efficient). Not enough to account for 25% range.

[techyiam]

6 hours ago, Uras said:

isn't this a problem with inmotion too? Inmotion seem to have their fair share of faults. Perhaps you're really trying to comment on build quality which is a different thing; it appears you can have a quality build with design or component faults.

No, we were talking about safety margins and safety features. He was essentially saying playing it safe was boring. 

On the V13, it has very generous safety margins. Also, safety features such as fail safe redundant hall sensor system, advanced smart BMS, and potted battery packs. The V13 blow away its competitors handily in these areas. The top speed cutout margin is set unprecedentedly high. 140 km/h free spin speed for a top speed of 90 km/h. 

Edited January 31, 2023 by techyiam

[2disbetter]

6 hours ago, Uras said:

Inmotion appears to be every bit as dangerous as other brands when they release new models.

Sure, but even you have to be able to see how the way the V13 is constructed makes it much safer than the surrounding competitions. I don't believe this is a point that can debated. The V13 is the best built EUC right now. For me that means something. For others it doesn't. 

[2disbetter]

1 hour ago, techyiam said:

Nope. That would mean Inmotion has to cross over to the Dark Side and relax safety margins. 

It depends. The margins that exist now are excessive. If the wheel top speed was bumped to 100 kmh (62 mph) would the safety margin really not be there? If they allowed more of the massive amount of torque possible on the motor to be manifest would it really stress the safety margins? I mean we don't need a ton, just a bit. The point is that the wheel has tons of room in its safety margins. What other wheel can say the same thing? 

[Robse]

1 minute ago, 2disbetter said:

It depends. The margins that exist now are excessive. If the wheel top speed was bumped to 100 kmh (62 mph) would the safety margin really not be there? If they allowed more of the massive amount of torque possible on the motor to be manifest would it really stress the safety margins? I mean we don't need a ton, just a bit. The point is that the wheel has tons of room in its safety margins. What other wheel can say the same thing? 

And 2 Nanoseconds after IM release of "fancy mode max speed 100 kmph firmware"  someone will cry out for more speed. Sure for that.  The Gotway gang riding the beeps on any wheel will not stop before their skulls are trashed on the asphalt.

[techyiam]

3 minutes ago, 2disbetter said:

The V13 is the best built EUC right now. For me that means something. For others it doesn't. 

Also when the V12 was released, its build quality was also among the best. Even after Abrams came out, the V12 still compared well. Abrams did have some parts of higher quality. But the basic design was better on the V12. Both the V12 and V13 were designed to be serviced. The way the battery packs were fastened onto the frame was a amateurish on the Abrams. Bolt holes don't line up.

 

2 minutes ago, 2disbetter said:

It depends. The margins that exist now are excessive. If the wheel top speed was bumped to 100 kmh (62 mph) would the safety margin really not be there? If they allowed more of the massive amount of torque possible on the motor to be manifest would it really stress the safety margins? I mean we don't need a ton, just a bit. The point is that the wheel has tons of room in its safety margins. What other wheel can say the same thing? 

Not according to Inmotion's CEO. If you ask Dawn, she would tell you she doesn't want any. She wants to decide for herself. 

There are various factors that affect the margin. And Inmotion has to use the lowest denominator. 

They have to assume the heaviest rider weight.. It has to take into account of headwind, slope, potholes, hard acceleration, hard braking, battery voltage, and etc.

 

[2disbetter]

11 minutes ago, techyiam said:

Not according to Inmotion's CEO. If you ask Dawn, she would tell you she doesn't want any. She wants to decide for herself. 

There are various factors that affect the margin. And Inmotion has to use the lowest denominator. 

They have to assume the heaviest rider weight.. It has to take into account of headwind, slope, potholes, hard acceleration, hard braking, battery voltage, and etc.

I'm not disagreeing with you, I'm simply pointing out that with no other wheel is there even a discussion to be had in this regard. The V13 has such impressive safety margins, and because of them has potential to be even better than it is right now. Yes this would mean a slacking of the safety margins. But the slim safety margins which Begode and BC (and potentially all other EUCs models) possess are already being circumvented just to get their wheels to do what they do now. The V13 has head room no other wheel does. This means it is flexible in a way none of the other wheels are. 

 

 

Edited January 31, 2023 by 2disbetter

[OldFartRides]

5 hours ago, soulson said:

I agree, the V13's seven parallel FET arrangement should be more efficient than the S22's two parallel FETs based on R_DS(on):

S22:
R_DS(on) = 4.9 mOhm
Parallel devices = 2
Total resistance = 4.9 mOhm / 2 = 2.45 mOhm

V13:
R_DS(on) = 9.5 mOhm
Parallel devices = 7
Total resistance = 9.5 mOhm / 7 ~= 1.357 mOhm

For any non-engineers following along, a lower resistance FET arrangement is better. The power ends up getting "used" wherever the resistance is – whether that thing can do useful work with it or not. If it can't do something useful, then it just gets hot. You don't want that thing to be the inverter, nor the battery. You want it to be the motor, because that's where useful work can be done.

Interestingly, the V13's FETs are also faster than the S22's FETs, so they should be more efficient based on the rise and fall time of the PWM, too. Unfortunately, we can't figure out what the efficiency of that process is without knowing the carrier frequency of the inverter. It's a balancing act, because if the frequency is too low, the FETs will run cool and efficiently, but the distortion in the inverter's output waveform will cause heating (inefficiency) in the motor's stator windings. Contrariwise, running the frequency too high will result in a smooth, relatively undistorted waveform that will make the motor run cool and happy, but it will make the FETs start sweating as they have to slew across the resistance function more often.

Yes, the battery is part of it. The battery has an internal resistance (you may also hear it called "equivalent series resistance" or ESR in engineerese), and any current drawn by the load attached to the battery must cross the battery's internal resistance, wasting power and producing heat. This is why the battery gets warm when it is used or charged (the current flows across the internal resistance when charging, too, just in the other direction). Indirectly, this is also the cause of "voltage droop" when the battery is under heavy load. All other things being equal, a battery with lower internal resistance will be more efficient and less susceptible to voltage droop.

Summing up...

• The controller is probably pretty efficient. If it wasn't, it would get hot, which it doesn't. So this probably isn't where the perceived low efficiency is coming from.
• The battery's calculated internal resistance is 225 mOhm (based on 60 mOhm cells in a 30S8P configuration). If the total system power is 10kW, 1.4kW is being wasted as battery heat (based on P=I^2*R). So we can think of the battery as being "86% efficient". I'm not sure how this compares to other wheels, but it sounds reasonable to me as a gut check. Even if other wheel batteries were 100% efficient (they're not), then this wouldn't result in the V13 getting 25 to 30% less range per watt*hour.
  • source: https://lygte-info.dk/review/batteries2012/Samsung INR18650-35E 3500mAh (Pink) UK.html
• The motor may be efficient or not. We don't know. If the problem is literally power efficiency, then the motor is probably the culprit.

There are a few other things that could be causing this that are not literally power efficiency:

• The V13 is heavier and therefore takes more energy to accelerate. Certainly a factor, but probably doesn't explain 25%.
• The V13 batteries are potted and therefore the cells are more exposed to the external temperature than on other wheels with similar capacity. Lithium ion cells have a sort of "preferred temperature range" where their energy density is highest. They like to be warm, but not hot. If it's very cold out, then the thermally conductive potting material may be cooling them off more than they'd like, reducing their ability to hold charge. It didn't look very cold in Marty's video, though. I doubt this is a major factor.
• The V13 may have a different "zero point" than other wheels. If wheel A says that a cell is fully discharged at 3.0V, but wheel B says that a cell is fully discharged at 2.9V, then wheel B will get a full watt-hour of extra energy out of that cell. If wheel A happens to be a V13 with 240 cells, then it would hit "0% charge" with 240 more watt-hours "left in reserve" than wheel B. Given Inmotion's behavior such as limiting charge to 4.185 volts per cell, I wouldn't be surprised to learn that they also limit discharge in a similar manner, although I have no evidence of this. A difference of just 0.1 volts per cell would result in a ~10% reduction in range. The benefit to this would be battery longevity. Lithium-ion cells will perform better over time if they're not discharged super deep.

Thanks for these !  “Parting the veil of mystery” for the rest of us.

[mrelwood]

 

14 hours ago, GHOSTTE said:

the Sherman S came out with the new hotness, hydraulic suspension.

Again with the hydraulic suspension?? It isn’t a thing! The ShermS suspension is just as hydraulic as all the others (excluding only V11). And just as “springy” as the S22. What’s new is the format, not the function.

 

10 hours ago, Uras said:

People like what they like, despite what you think or believe. There seems to be a real inmotion bias in this forum - I don't get it.

Well, one could say that people seem to like Inmotion then…

[GHOSTTE]

48 minutes ago, mrelwood said:

Again with the hydraulic suspension?? It isn’t a thing! The ShermS suspension is just as hydraulic as all the others (excluding only V11). And just as “springy” as the S22. What’s new is the format, not the function.

What are you talking about? The Sherman S is the first EUC to feature true hydraulic suspension, it's why it's been so popular because it's a new tech in EUCs because all other suspension wheels up until this point have been air suspension. Air suspension and hydraulic suspension are two different suspension systems each with their pros and cons, I don't know why you're spreading misinformation.

[Robse]

30 minutes ago, GHOSTTE said:

What are you talking about? The Sherman S is the first EUC to feature true hydraulic suspension, it's why it's been so popular because it's a new tech in EUCs because all other suspension wheels up until this point have been air suspension. Air suspension and hydraulic suspension are two different suspension systems each with their pros and cons, I don't know why you're spreading misinformation.

what makes s suspension a "true hydraulic suspension"?  It's hydraulic if the shock is filled with liquid (oil) , or?

Edited January 31, 2023 by Robse

[GHOSTTE]

11 minutes ago, Robse said:

what makes s suspension a "true hydraulic suspension"?  It's hydraulic if the shock is filled with liquid (oil) , or?

Pretty much, both air and hydraulic suspensions have their pros and cons. Here's an article discussing it with regard to electric bicycles

https://polarnaebike.com/blogs/news/what-is-a-hydraulic-suspension-system

[Mango]

12 hours ago, Uras said:

There seems to be a real inmotion bias in this forum - I don't get it.

Is there? Maybe a few outspoken individuals skew bias towards Inmotion products.

But since you quoted me, I own 3 KS wheels, 4 Begode wheels, 2 Veteran wheels, and 2 inmotion wheels — hardly bias for Inmotion.

[Robse]

14 minutes ago, GHOSTTE said:

Pretty much, both air and hydraulic suspensions have their pros and cons. Here's an article discussing it with regard to electric bicycles

https://polarnaebike.com/blogs/news/what-is-a-hydraulic-suspension-system

ok, so in your opinion, what suspension type does a KingSong S22 have?

[GHOSTTE]

21 minutes ago, Robse said:

ok, so in your opinion, what suspension type does a KingSong S22 have?

Coil

[Robse]

Just now, GHOSTTE said:

Coil

So the Sherman has no coils?

[GHOSTTE]

Just now, Robse said:

So the Sherman has no coils?

Which Sherman?

[Paul A]

hydraulic

/hʌɪˈdrɒlɪk/

Learn to pronounce

See definitions in:

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Mechanics

Civil Engineering

adjective

1. 1.

   denoting or relating to a liquid moving in a confined space under pressure.

   "hydraulic fluid"

    
2. 2.

   relating to the science of hydraulics.

   "hydraulic analysis of streams"

[Robse]

27 minutes ago, GHOSTTE said:

Which Sherman?

GHOSTTE said:

The Sherman S

[GHOSTTE]

19 minutes ago, Robse said:

The Sherman S

You tell me

 

[Robse]

25 minutes ago, GHOSTTE said:

You tell me

 

interesting, but nothing "new" - now you tell me, whats the difference between these two suspension shock absorbers?  Is it that one of them has the spring on the outside, the other the inside?

[GHOSTTE]

First is a true hydraulic suspension shock and the second is a coil-over with adjustable rebound and compression. If you want more information on the two go Google it.

[Robse]

7 minutes ago, GHOSTTE said:

First is a true hydraulic suspension shock and the second is a coil-over with adjustable rebound and compression. If you want more information on the two go Google it.

Right and then not.  In Denmark we have a way of speaking which probably covers this well:

Pølse for og pølse bag, pølse har den samme smag. 

[Lesleigh Gonzales]

Challenger is in the house at NELTREK! We're super excited. 

 

Ride safe,