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marc

Gotway Msuper 18 inch High Speed Latest Review: April 2015

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EDIT: Meanwhile, the problems mentioned below are solved: see my next posts. and in this text marked with "EDIT:..."

 

I have received my Gotway Msuper 18 inch HS 2 days after sending from Hong Kong. 15 000km in 2 days (waiting for custom taxes of half day included) was impressive from DHL. besides it was in weekend (also included).

I had first chosen for a middle speed because I knew that I will not ride +-34-40km/h.  But afterwards I let it change the motherboard to High Speed version (40-44km/h) due to my weight (63kg) and due to the flat roads here and due to the members of this forum who had bought High Speed.  Nobody complained about the low torque but the torque is very low.

 

EDIT:

After two discharges of my gotway (=120km), I am now sure to say that the "shivering effect" happens only at high battery voltage. Beneath 50% of battery capacity (=beneath 60V), it nearly does not shiver any more. That means that the balancing unit cannot work with high voltage. I imagine that the voltage (67V when full) is transformed to a lower voltage for the balancing unit with a constant factor. For example if the balancing unit works at nominal 10 V (if battery is at 60V), then when battery voltage is 67V ==> the balancing unit voltage will be 11,2V instead of 10V and that can increase the errors, decrease the accuracy of the balance system, especially during acceleration where finding balance is more difficult than a constant speed. I still wonder why nobody has this problem. is this a production error that happened only to me.

 

EDIT: motherboard change will not affect number of windings of the coil so it will not affect the torque of the wheel.

 

 

Even at very low speeds 3km/h it vibrates during accelerating, even though I am only 63kg and the road is extremely flat without inclination.  I feel that the wheel can not accelerate that fast even though my acceleration is slowly because once I stepped off from my previous unicycle when it was at his max. speed (=18km/h).  So I ride slowly now.  But I did not fall: no other part of my body than the soles of my shoes touched the sole.  But after this I have chosen to buy a faster one.

And now the torque is the problem because of high speed for same power. I know there is no other unicycle in the world that is more powerful than Gotway Msuper 18 inch which has a RATED (not maximum) power of 1000W.  Other unicycles' producers like to mention the max. power of 1500W however the rated power is 500W.

 

My previous 350W-135Wh unicycle's range was 6-8km with one charge: I think the real capacity was 85Wh however the seller said 135Wh.

Another disadvantage: the batteries are charged with 2 Amperes. If this is the current that passes over every cell of the battery, it is too much. It will decrease the one-discharge capacity and also the whole lifecycle capacity. You can use the battery 1,5 year instead of 5 years if you are rude (sending high currents) to batteries.  Also your one-discharge range will decrease: instead of 80km range you will have 60km range.  Also for gsms it is like that.  I charge my gsm with 0,5A instead of 1A and it lasts longer than when I charge with 1A or 2A.  But people ask for faster charging; factories produce it and users don't know why their gsm battery lasts 10h after 1 year and half however it was 15h at first achievement.  I prefer waiting 5h more for doing 120km instead of 60km with one charge.  

Another thing that nobody mentioned until now is the thickness of the tire, not the wheel size.  Also the very thick  tire of the Gotway 18 makes it to ride very comfortable.  

I think 850Wh is too much for a battery: if you charge 680Wh battery with 1A instead of 2A, you would touch 80km range, I guess.

Is there a electric unicycle that has rated power of 1500W that exists in the world? But I am speaking about rated power 1500W: so it means max. power 4500W.  

WHen you turn on your Gotway 18 too fast after laying it on the ground, generally you don't think about the horizontal alignment before setting it on.  So if the wheel is set on on a slant position, with steps inclined downwards, then it continues riding with inclined steppers, which is a big advantage because otherwise the wheel will fly from your hands because of the maximum forwards inclination.  That is an important advantage of the Gotway that I did not read from other members of this board.  My previous did not have this option. It costed only 120USD and this Gotway 18 costed 915USD without shipping and taxes.  Shipping costs 150USD/piece if it is in 2 days. If

I don't know how you can pull the wheel with a trolley without losing sideways balance because the balance of 14kg depends on the contact point between trolley and unicycle which will be too weak in comparison with the torque on this point.  If you exclude torques on this point, by more pulling it upwards than pulling it sideways to keep balance, then maybe it is possible to pull it without problems.
 

Can anyone say if the torque of the rockwheel is better than Gotway 18? I am already thinking of buying a unicycle with a better torque.

Edited by marc

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Hello Marc, welcome to the forum.

I believe you will find that you cannot change the version of your M18 just by changing the control board. The three different versions have different numbers of windings in their coils to give the different speed/torque characteristics.

Strange that you are lacking in torque with your relatively light weight, as far as the vibration is concerned have you checked that the wheel nuts are fully tightened?

The trolley handle is meant to be used with the unit turned on so that the handle remains upright whilst you are wheeling it then you will find it relatively easy to use.

Edited by Gimlet

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This is the first time in my life that I have heard that charging. Battery slower will mean it can carry more charge. Sure if you charge a cheap cell at more than 1c (so for a 5000mAh cell that would be 5A) it will shorten its life span in the long run. But you do realise that means you could (taking for granted that the wires in the wheel are thick enough) charge your 860Wh battery with 12A safely.

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There was a vibaration problem too from a indian guy at Facebook.

I do not have acess there and also do not know the solution (if any)

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Can anyone say if the torque of the rockwheel is better than Gotway 18? I am already thinking of buying a unicycle with a better torque.

I will test this soon with my Rockwheel GR12 (compare to the both GW I have)

See my posting:

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None of the Rockwheel wrestling is not in the same league with 18 Gotway. Not under any circumstances.

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This is the first time in my life that I have heard that charging. Battery slower will mean it can carry more charge. Sure if you charge a cheap cell at more than 1c (so for a 5000mAh cell that would be 5A) it will shorten its life span in the long run. But you do realise that means you could (taking for granted that the wires in the wheel are thick enough) charge your 860Wh battery with 12A safely.

Dear Sunny, I have done a PhD on Lithium batteries. I have done tests with various currents and have published them on international symposia. Lithium batteries are relatively new and there is not sufficiant research done on these subjects yet.  Industry does what 99% of the customers ask and if there are problems that only can be seen by 0,00001 % of the customers (people like me), they don't care about this problem.  They don't care that they will loose such less customers. 

Edited by marc
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Meanwhile the problem of vibrating has nearly stopped.  I do not know why. 

I hear

1 beep at 21km/h on gotway app

2 beeps at 23-24km/h

 

however it was supposed to be the high speed version with beeps moved to 30-34-37km/h. probably they did not change the beep speeds.

 

Since it was vibrating in hills, I could not accelerate in hills. Now without the vibration, I climb the hills better than before. I guess 10km/h in road inclination of 7-10 degrees upwards which is good until Gotway will hopely produce in the future the 2000W (rated power) unicycle.

Edited by marc

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Another disadvantage: the batteries are charged with 2 Amperes. If this is the current that passes over every cell of the battery, it is too much. It will decrease the one-discharge capacity and also the whole lifecycle capacity. You can use the battery 1,5 year instead of 5 years if you are rude (sending high currents) to batteries.  Also your one-discharge range will decrease: instead of 120km range you will have 60km range.  Also for gsms it is like that.  I charge my gsm with 0,5A instead of 1A and it lasts longer than when I charge with 1A or 2A.  But people ask for faster charging; factories produce it and users don't know why their gsm battery lasts 10h after 1 year and half however it was 15h at first achievement.  I prefer waiting 5h more for doing 120km instead of 60km with one charge.  

Another thing that nobody mentioned until now is the thickness of the tire, not the wheel size.  Also the very thick  tire of the Gotway 18 makes it to ride very comfortable.  

I think 850Wh is too much for a battery: if you charge 680Wh battery with 1A instead of 2A, you would touch 120km range, I guess.

Is there a electric unicycle that has rated power of 1500W that exists in the world? But I am speaking about rated power 1500W: so it means max. power 4500W.  

I wonder why nobody complained about torque: maybe there is a real problem with my unicycle.  

Surely as just about all eucs that are available at the moment use 2 amp chargers the larger the battery you get the gentler your charge cycle is going to be as it's spread over the total number of cells installed? :)

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Dear Sunny, I have done a PhD on Lithium batteries. I have done tests with various currents and have published them on international symposia. Lithium batteries are relatively new and there is not sufficiant research done on these subjects yet.  Industry does what 99% of the customers ask and if there are problems that only can be seen by 0,00001 % of the customers (people like me), they don't care about this problem.  They don't care that they will loose such less customers. 

It is great to have someone to talk to who really knows the ins and outs of batteries and their chemistry. My knowledge is simply what I have gathered in a few years of RC. So just to come back to the original issue at hand, which is why I even posted, - do batteries hold more charge if they are charged slower? It is really the first time that I have heard this. Either way, we can also discuss this further via PM if you would like so that we don't hijack the Gotway M18 thread. 

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In my experience, really fast charging can leave the battery slightly less, at least Lipo battery. But it is not at all significant, if not download absolutely unimaginable speeds.

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Well think of a shorted battery, very quick discharge, causes rapid expansion and a fire, slow charge will always be better for life of battery, hense you get more 'charge' out of battery.

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I drive a electric car and it can be charged with arround 1C  (as fast charging Chademo) OR at a houshold outlet with J1772 and arround 0.2C.

YUSA did test and compare both charging and what happen to the battery LiPo and they did not find almost any difference after 1000 cycles.

The new KIA Soul EV will be charged at arround 1.7C (average).

At the end from 70 or 85 to100% and with a low battery temperature the charging current will drop significant and even with a normal battery temperature it will drop far below 1C

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There is also the effect of battery management system. A good battery means in fact a battery with good battery management system so that the current is equally divided into different cells. If not, the weakest battery will become weaker and weaker because he cannot follow the performance of other cells.  This system has to detect it and ask less performance from this cell. 

 

So charging/discharging with low currents and having a bad battery management system will still decrease the performance of the battery.

Edited by marc

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I found that I was riding backwards.  Maybe it is due to that the wheel was shivering. Now it stopped vibrating during accelerating.

I reached 3 beeps.  I think, if I had the high torque version I could not ride that easy at 3 beeps.

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Three beep riding is very simple on the high torque version. Why do you think it would be difficult?

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since the max. speed is 28km/h and three beeps is at 28km/h, you should be careful when you approach that speed, the motor will shut down.

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No, first warning is 2 beeps, second warning is 3 beeps and final warning is 4 beeps which is continuous with no pauses in between.

Keeping it on 3 beeps with just the occasional 4 beeps creeping in isn't that hard.

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No, first warning is 2 beeps, second warning is 3 beeps and final warning is 4 beeps which is continuous with no pauses in between.

Keeping it on 3 beeps with just the occasional 4 beeps creeping in isn't that hard.

 

When Gimlet said "no pauses in between" he didn't mean a continuous tone.  It means beep beep beep beep beep beep beep beep beep beep beep beep.  If you play musical instruments it's like "four beats per measure" type of thing.

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Which direction is "backwards".  The program is directional?

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In theory the motor doesn't have a backwards. The pedals are asymmetric and the inverted vee is supposed to be at the front but we find it difficult to get enough forward pressure on the pedals going up steep hills this way so we ride it backwards.

I am in the process of making some pedal toppers/extenders to rectify this minor problem. I post when they are finished. :)

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I squeeze if necessary, lower legs firmly against the unit and printing them forward acceleration.
Thus, gains more strength on uneven terrain. And at the same time the machine will remain under better control.

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I squeeze if necessary, lower legs firmly against the unit and printing them forward acceleration.

Thus, gains more strength on uneven terrain. And at the same time the machine will remain under better control.

That is hard work if you have to do it for long. I also plan to put some plastic pipe through the front handle gap with a little pipe insulation for comfort so that I have something to lever against rather than having to grip tightly. It only needs to stick out a centemetre or so.

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If you look at the aerodynamic design of the pedals you will see the direction of the gotway but even if I ride in the right direction I have again shivering or vibrating problem after recharge.  Now I am thinking of the following reason for vibrating: maybe the motor cannot send energy to the batteries during downhill or braking because the battery is already full. because before the battery was not full and it did not vibrate.  but even during accelerating it vibrates, again.

or maybe it is due to the fact that it has fallen one time.

or due to surfaces that are not flat and that make the motor vibrating so that it destroys the balance of the system.

I don't know

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I now have gotway 18 disassembled into pieces. I will now bring the same pedals 2cm. I'm getting more ground clearance and accelerating the needed less forces noble evening when the pedal is closer to the center point.

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