ROCKWHEEL GT16

[US69]

13 hours ago, Lorents said:

+1

The new 92.2V version seems to use 22S packs. This is a 10% increase in voltage (and watts) from the existing 84V model. 

My 84V GT16 cruises comfortably at 35km/h (~200 Lbs) so the 92.2V version could probably cruise closer to 40km/h - unless they have made it as a high speed/low torque version for featherweight riders...

Thats also a 10% increase in the chance that one of the 22 cell is failing and from 16 to 22 cells a over 40% increase :-)

Hopefully they -as allways ;-) - got that in mind when stacking and stacking more up, and at least use a good celltype with low resistance. And not just the cheapest possible available as on the 84Volt model ;-) 

Next on this success-story is the 24 cell version with 100,8 Volt.....äääh, Sorry, for better promotion: the 100 Volt Gt16s100+++, with 90kmh....., others failed on 100(,8) Volt? That must have been companies with not such a historic good qualiy control as Rockwheel has :-) 

(Sorry, guys, just a bit of Sarcasm for fun)

 

Actually i like the 84Volt Gt16....and only heard good things about its performance....just would have been nice if they have sorted out the announced problems of (for example) French Resellers, before they even step up the game once more! 

[US69]

10 minutes ago, houseofjob said:

Sure about that price? Reports are the revisioned GT16 will cost more than the current GT16 listings, and the Wheelers Paris store GT16 page sure seems to reflect this.

you have to know that official european sellers all directly have to pay about 26% import taxes (not speaking about normal taxes/VAT) on these type of products...

Thats why the european EUC markets are in general a lot more expensive than USA or other countries and having a big problem with chinese online sellers....

here in this example, you get the latest/newest 84volt model from ali seller "rockwheel store" (whos owner yi chen is partly involved in this model) for about 1100 dollar->1000 euro (instead of 1700euro).....and that including transport AND all taxes delivered to your door....

[houseofjob]

@KingSong69 I know. I'm not getting all this from just that Wheelers page, more from Asian reports.

Could turn out similar price, but not according to what I've read from abroad.

Edited June 9, 2017 by houseofjob

[Scatcat]

4 hours ago, KingSong69 said:

Thats also a 10% increase in the chance that one of the 22 cell is failing and from 16 to 22 cells a over 40% increase :-)

Hopefully they -as allways ;-) - got that in mind when stacking and stacking more up, and at least use a good celltype with low resistance. And not just the cheapest possible available as on the 84Volt model ;-) 

Next on this success-story is the 24 cell version with 100,8 Volt.....äääh, Sorry, for better promotion: the 100 Volt Gt16s100+++, with 90kmh....., others failed on 100(,8) Volt? That must have been companies with not such a historic good qualiy control as Rockwheel has :-) 

(Sorry, guys, just a bit of Sarcasm for fun)

 

Actually i like the 84Volt Gt16....and only heard good things about its performance....just would have been nice if they have sorted out the announced problems of (for example) French Resellers, before they even step up the game once more! 

Panasonics AFAIK, haven't actually cut the packs to check.

[Mono]

On 2017-6-8 at 7:23 PM, Mono said:

We have maximal torque at zero speed (where we also have zero power) and maximal power at half of the maximal speed (where we have of the maximal torque).

needed to read (where we have half of the maximal torque). Editing is disabled, so that the way to go then 

[Lorents]

On 9.6.2017 at 9:09 PM, KingSong69 said:

Thats also a 10% increase in the chance that one of the 22 cell is failing and from 16 to 22 cells a over 40% increase :-)

I wouldnt worry too much about that. The GT16 uses 4 x 22S packs in parallell, each pack protected with its own BMS.

Higher voltage means less amps for the same amount of watts so it should be easier on both the cells and the electronics (unless you use that 10% extra to push the limits further) 

[US69]

1 hour ago, Lorents said:

I wouldnt worry too much about that. The GT16 uses 4 x 22S packs in parallell, each pack protected with its own BMS.

Higher voltage means less amps for the same amount of watts so it should be easier on both the cells and the electronics (unless you use that 10% extra to push the limits further) 

I would say one Thing has nothing to do with the other...

On directly parallel installed packs Gotway  -fortunatly!- has on newer wheels installed a "communication" line (or "balancing" line) between their 800Watt packs, additionally to the Charge and discharge-wires!

For a very good reason......back to Rockwheel:

Think about one or two  cells dying/failing in one of your four parallel packs, and the BMS protecting this ONE pack (not protecting the complete Combo) shuts down the pack or (same worse case ) keeps the pack going but with 8,4 Volt less......You have a nice 4 parallel pack, where one of the packs is totally out of balancing....and the Rest of what happens then i let go to everyones own mind....

 

There is a very good reason why "daisy chaining" was done by some companies ....paralleling packs must be done with a lot of technical knowledge....only "y-cabling" can lead in worst case to a burn/fire/explosion...

[Lorents]

1 hour ago, KingSong69 said:

I would say one Thing has nothing to do with the other...

On directly parallel installed packs Gotway  -fortunatly!- has on newer wheels installed a "communication" line (or "balancing" line) between their 800Watt packs, additionally to the Charge and discharge-wires!

For a very good reason......back to Rockwheel:

Think about one or two  cells dying/failing in one of your four parallel packs, and the BMS protecting this ONE pack (not protecting the complete Combo) shuts down the pack or (same worse case ) keeps the pack going but with 8,4 Volt less......You have a nice 4 parallel pack, where one of the packs is totally out of balancing....and the Rest of what happens then i let go to everyones own mind...

I guess it all depends on how the BMS is implemented and what you mean by a "failing cell". For me, the advantages of higher voltage clearly outweighs the risk of a failing cell  

If failing cells where a big concern we would be running 1S packs @ 3.7V (~80P) with the GT16 drawing 850 amps at max 

[Keith]

1 hour ago, KingSong69 said:

shuts down the pack or (same worse case ) keeps the pack going but with 8,4 Volt less.

That absolutely, simply, cannot happen if you have parallel packs. The voltage at the parallel point MUST remain the same always it can do nothing else. So if a cell were to start to fail it would be "topped up" by the other packs and no further current would be drawn from that pack until those packs reached the same voltage.

A failing cell tends to act like a short circuit but might possibly fail open circuit as well so there are only two alternatives:

1. the failed cell will attempt to lower the voltage of that pack but current flowing into that pack will hold the voltage up. Even if the cell failed in such a way as to be a full, zero ohms, short then current will still flow until it reaches a level where the total series resistance of that pack causes a voltage rise as V=IR where total V for the pack is the voltage of the remaining cells plus the V=IR drop due to the current flowing in.
2. The failed cell goes open circuit in which case that pack simply stops contributing to the current at all

Of course packs usually have cells in parallel within the pack so multiple parallel cells would need to fail or be dragged down by the faulty cell. 

Should the BMS be monitoring and controlling the pack then, yes, I would expect it to simply shut that pack down if one cell, or cell group, went low voltage and was in danger of being permanently damaged. This would force the remaining packs to take the load. I would sincerely hope that BMS in our wheels do not do that and, ideally they should signal the main processor to instigate tiltback or alarm if a BMS sees an unsafe condition on its pack.

[Mono]

On 2017-6-10 at 1:45 AM, Scatcat said:

Thats also a 10% increase in the chance that one of the 22 cell is failing and from 16 to 22 cells a over 40% increase :-)

which is a rather insignificant increase if we talk about probabilities of 1e-6 to begin with. Where does the 10% come from? 

29 minutes ago, KingSong69 said:

You have a nice 4 parallel pack, where one of the packs is totally out of balancing....and the Rest of what happens then i let go to everyones own mind....

As long as the defective pack doesn't allow inverted current flow, i.e. shortens the other packs, or catches fire, it looks like the perfect fail-safe scenario, 3 parallel packs are left to do what they are supposed to do.

[Mono]

38 minutes ago, Lorents said:

For me, the advantages of higher voltage clearly outweighs the risk of a failing cell

What exactly did this guy get wrong?

He claims that with lower voltage, the only difference is that we need thicker wires and connectors, while it doesn't change the performance at all. AFAICS he is right, plus he seems to be extremely versed.

Edited June 14, 2017 by Mono

[Keith]

7 minutes ago, Mono said:

What exactly did this guy get wrong?

He completely ignores I squared R losses, the very reason that long distance power grids use umpteen thousand volts.

But also the Kv of motors needs very much to be taken into consideration especially as there is a direct relationship between Kv and torque. A low Kv ( I.e. A low RPM per volt value) will be produced by a high number of turns of thin wire on each pole of the motor; it will not be able to take much current but it will need a high voltage to get it to spin fast enough for a good top speed. A high Kv is produced by a low number of turns, low turns mean there is room for thicker wire, or more usually multiple parallel strands of thin wire as that will fill the available space on the armature better. So a high kV requires much lower voltage for the same RPM and can be wound so as to take the much higher currents needed to produce the same amount of power at that RPM. 

At a high RPM, I.e. At cruising speed both solutions will have similar efficiencies but it is at very low speeds such as just balancing and accelerating from a stop that a high Kv solution will be capable of drawing very high currents because of the thicker wires/ lower resistance in the motor. Efficiency will be a lot lower and heating increased. in practice there is an optimal voltage/Kv/current/voltage safety/ price solution which is where we found ourselves with the 60V solution. Possibly 84V is a better solution now that cell prices are less of an obstacle? but my motor theory isn't quite up to knowing how to calculate that?

[US69]

27 minutes ago, Keith said:

That absolutely, simply, cannot happen if you have parallel packs. The voltage at the parallel point MUST remain the same always it can do nothing else. So if a cell were to start to fail it would be "topped up" by the other packs and no further current would be drawn from that pack until those packs reached the same voltage.

Yeah...that can not happen, you are right ..in a parallel System the cells where topped up by each other, they MUST compensate each other

But do you know what happends if you connect a 70 Volt and a 78,4 Volt pack and they try to compensate this  in a nanosecond?  Have  a lot of Fun :-)

27 minutes ago, Keith said:

Should the BMS be monitoring and controlling the pack then, yes, I would expect it to simply shut that pack down if one cell, or cell group, went low voltage and was in danger of being permanently damaged. This would force the remaining packs to take the load. I would sincerely hope that BMS in our wheels do not do that and, ideally they should signal the main processor to instigate tiltback or alarm if a BMS sees an unsafe condition on its pack.

That would mean that our BMS's are connected to the main board....which they are not!!! (Exception some ninebot, Inmotion)

 

Gotway has detected the potential danger of paralleling packs just by "y-cabling" and because of that, they are giving those packs/wheels now an "extra" circuit, so that Beside the Charge and De-Charge cable all new GW models like ACM, V3 and Monster have a seperate communication cable running between their BMS's!!!

Kingsong in their new 16S model got away from daisy chaining, BUT didn't just "y-cable" their packs...they lead each of both packs directly to the board where is taken care of the paralleling. 

 

That's what i want to say with my post....Certainly You can Parallel complete packs...but you must do it totally right!!!

Otherwise you can end up with a parallel System where the protections of the BMS of each pack are Kind of undermind/bypassed by the parallel Connection itself, which then in the worst case can lead to catastrophic failure.......

I haven't invented this Scenario in my "Little knowledge electronic vaped away brain" :-) I got this out of several  different communication with Chris from 1 Radwerkstatt, who  explained me the Advantages and disadvantages of "daisy chaining", "real paralleling", BMS protections and their Limits in paralleling and about his talks with KS to do it the right way....

[Lorents]

37 minutes ago, Mono said:

What exactly did this guy get wrong?

He is talking about e-bikes that draws ~1000 watts and sais it is no problem to make a 12V e-bike that keeps up with a 72V e-bike. He also sais that the 12V version would draw lots om amps and requires fat copper wires, bigger connectors, etc.

If you want a powerful EUC you can either turn up the amps or the voltage (or both) to get a certain amount of watts.

IMHO the advantages of increasing voltage instead of amps are:

- Less resistance for the same amount of watts - generates less heat -> more efficient
- Smaller electronic components and wires
- Less of a voltage drop under load and that means higher sustained voltage during driving

 

Edited June 14, 2017 by Lorents

[Mono]

35 minutes ago, Keith said:

He completely ignores I squared R losses, the very reason that long distance power grids use umpteen thousand volts.

If so (I don't think he does), don't you think he would have good reasons to do so? I mean, is he that dumb that he can ignore something that basic for no good reasons in his core competence area?

Re long distance power grids: sure, we need roughly 1000 times thinner wires at 110kV than at 110V, so the obvious reason is to save lots and lots of material and the structure which would need to be built to support its weight. Or in other words, we need to install only one cable of a given size instead of 1000 cables.

Edited June 14, 2017 by Mono

[esaj]

1 hour ago, KingSong69 said:

That would mean that our BMS's are connected to the main board....which they are not!!! (Exception some ninebot, Inmotion)

Old Firewheels did that, if the cable was left unconnected, the wheel would not power the motor and instead kept repeating a message, something like "Low battery or bad cell in battery". KS16S's have a third wire coming from each pack, I don't know for sure, but I'd suspect it's for mainboard <-> BMS -communications (something like a timing-based 1-wire protocol? might also be only in one direction or just voltage level ok/fault-signal):

I mean the thinner blue ones on the two male MT60's nearer to the center of the picture. The one with yellow/blue/green-wires is for the motor.

 

Edited June 14, 2017 by esaj

[US69]

12 minutes ago, esaj said:

Old Firewheels did that, if the cable was left unconnected, the wheel would not power the motor and instead kept repeating a message, something like "Low battery or bad cell in battery". KS16S's have a third wire coming from each pack, I don't know for sure, but I'd suspect it's for mainboard <-> BMS -communications (something like a timing-based 1-wire protocol? might also be only in one direction or just voltage level ok/fault-signal):

I mean the thinner blue ones on the two male MT60's nearer to the center of the picture. The one with yellow/blue/green-wires is for the motor.

 

Ok, so Firewheel was also a step before the competition as it seams :-)

 

Yip, those Connections i mean, did not know exactly what they do, but it is obvious that KS not just  "split" the two parallel packs by a "y-cable", but instead connect each of the packs to the Mainboard, or? That would be the first time one of our EUC Producers would do something "more cost intensive" without any reason....

 

Also here Gotway...a bit hard to see:

That's a V3 BMS with 8!!! Cables:

2 for charging

2 for de-charging

and

4 for the communication with the other installed parallel pack....

[WaveCut]

Russian users GT16 broken axis

[houseofjob]

1 minute ago, WaveCut said:

Russian users GT16 broken axis

 

Rider's weight? Was this from jumping?

[WaveCut]

Will update with details later

[WaveCut]

Here comes the details:

86 kg newbie rider, not jumper. Issue was progressing for a couple of days (noticed scratching the motor). 

[kasenutty]

The GT16 is the most exciting and most frightening wheel available today. 

[houseofjob]

1 minute ago, WaveCut said:

Here comes the details:

86 kg newbie rider, not jumper. Issue was progressing for a couple of days (noticed scratching the motor). 

 

Damn, thanks for that.

Was this a recent production GT16? or from the initial December 2016/January 2017 batch, or after?

[Scatcat]

4 hours ago, WaveCut said:

Russian users GT16 broken axis

Damn! I see they make the same mistake as everybody else, flattening an already to narrow axle...

Why can't they flatten just 5mm less of the axle length, so that the first bit in the pedal assembly closest to the wheel is the full axle diameter without any weakened spots? And preferably flatten it less too, the torsion shouldn't be all that hard to take even if more of the axle thickness is kept.

@陈小杰 This shouldn't happen, either use a bigger axle or take steps not to create weak spots.

Edited June 15, 2017 by Scatcat

[litewave]

4 hours ago, WaveCut said:

Here comes the details:

86 kg newbie rider, not jumper. Issue was progressing for a couple of days (noticed scratching the motor). 

 

OK then, Rockwell GT16 now deleted from my wishlist.