Gotway Msuper 18 inch High Speed Latest Review: April 2015

[Gimlet]

I went out for my first decent length ride on the M18 yesterday. To the next town and back which was a fraction under 10K each way. The path on that route is very narrow and badly maintained with huge puddles and potholes and overgrown hedgerows which forced me to crouch so low that at some points I was almost sitting on the case. Couldn't use the road as it is a 60 mph main road with loads of traffic even on a Sunday, most of whom are doing well over 60 mph.

Anyway to get to the point. I noticed that on a couple of occasions after crossing intersection and remounting that if my feet were farther back than usual on the pedals it seemed to upset the balance of the machine and make it wobble a fair bit at higher speeds on the rough surface. It was soon sorted by just adjusting my riding position a little so that my feet were well forward projecting off the front of the pedals. This seemed to sort out all the wobble problems.

[Waxil Davidson]

I just received a Gotway MSuper 18, and it seems the wheel is wobbly. I cannot go over 12mph without becoming very unstable and it's like riding on an egg, as I'm going up and down on it. 

 

Is this a known issue? Is there a way to fix it? Or is it more likely the wheel is just got damaged, and bent the wheel at the factory? 

 

 

[Gimlet]

Check the bead of the tyre is on true with the wheel rim. Some have found it necessary to let the air out to reset the tyre straight on the rim.

[EUC Extreme]

In my own, I noticed that, an inner tube is a little too big and will easily double. If not ilam into the work, see that the inner tube is not bad.

[marc]

I just received a Gotway MSuper 18, and it seems the wheel is wobbly. I cannot go over 12mph without becoming very unstable and it's like riding on an egg, as I'm going up and down on it. 

 

Is this a known issue? Is there a way to fix it? Or is it more likely the wheel is just got damaged, and bent the wheel at the factory? 

I had the same problem with my previous unicycle. It is because the tire is pumped too much. I suppose that there is no really pressure regulation in the CARGO airplanes so that the environment pressure low when the airplane is at 10km from the earth. When the environment pressure is low, the tire will swell up.

 

You have to decrease the pressure of the tire.

 

I hopely have solved your problem. Now, my problem: Do you feel vibrations during accelerations, like me? During acceleration the mine cannot rest horizontal, it shivers. when the speed is nealy constant, it does not shiver any more.

[marc]

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?

[Shady Tools]

I have had wobble before but I think it's usually down to my foot position.

I just got 2 or 3 beeps at just over 30kph whilst going down a hill though. I'm not sure if that's the actual limit or if the beeps are set too early.

 

I requested them to be set at 35, 37 & 39kph. I only seem to be able to get around 15kph going uphills though. This could just be me needing more practice & confidence though.

[Shady Tools]

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.

My beeps set in at around about 16/17mph but I requested them to be changed to 35, 37 & 39kph

When I did the lift test, they all sounded quite similar all the way up to cut off point (I guess that could have been fast acceleration) so I just ease off when I hear them. It's usually saying around 31 - 33kph on the app when they start.

 

It only got into the high 30's before cutting out during the lift test though.

[Luiz]

Hi guys. 

I am new to the forum but already got the eucs bug . I have recently upgraded from an x3 to an IPS 121 and i was so impressed with the power of this wheel  that i would like to buy the gotway 18  m super which i reckon is the most powerful euc . Could you tell me how can i bring one to uk.

[Shady Tools]

Contact either Jane Mo or Kevin Lee. They're both reputable dealers & are both on this forum & the pages on Facebook.

[MetricUSA]

I wish I mentioned this in my earlier comment, 2 amp charger for this eu should not be a problem, remember you actually have three packs in it for 680 wh battery, so divide 2 amps by 3, only .67 amps per pack. If you had a 860 wh battery, you would divide by 2 amps by 4, now only .5 amps per pack.

[esaj]

I wish I mentioned this in my earlier comment, 2 amp charger for this eu should not be a problem, remember you actually have three packs in it for 680 wh battery, so divide 2 amps by 3, only .67 amps per pack. If you had a 860 wh battery, you would divide by 2 amps by 4, now only .5 amps per pack.

As far as I know, the 680Wh version has 4 packs (probably 4 * 172Wh = 688Wh actually), so 0.5A per pack for 2A charger... I don't think there are single packs with more than 210Wh (60V * 3.5Ah). I recall someone saying that the "standard" 860Wh MSuper actually has five 172Wh packs. And the >1kWh packs that 1Rad Werkstatt sells are 5 * 210Wh (although they calculate it a bit funnily with more precise nominal voltage of 59.2V times 3.5Ah per pack = 207.2Wh, then round it down to 207Wh and calculate the total as 207 * 5 = 1035Wh).

The Gotway charger I bought from vee actually was a 4A charger, and I've used it with the Firewheel, 2A per pack, but as it's less than 1C per pack (2.2Ah cells), it still should be safe.

[Shady Tools]

I set up a faker number in my phone called EUC Battery & text it the voltage of the battery, where I've been & what time I put it on charge & what it's on when it's finished. 

As far as I can tell, I get just over 1V per half hour of charging. My charger has 2 unticked boxes on it saying 1A & 2A so I'm not sure what power it is.

The fan just started sounding dodgy on it though & I would like a faster charger for quick boosts while I'm out on big journeys.

What's the difference in charging time with a 4A charger? I'm guessing about double a 2A charger?

Plus, how powerful can I go before it's bad for my High Speed 850wh Gotway?

 

Thanks.

[zlymex]

I bought MSuper MS 680Wh, opened the covers and the battery wrapping.
There are two battery packs in it, each consist of 32 Panasontc NCR18650PF cells.
I added another DIY pack of 16 Panasonc NCR18650B making total capacity of 880Wh.

For fast charge, I bought five 5A chargers(4 for my friends who also own MSuper) but no good at all. Refund them and made five Y splitors to let two 2A charger charging the EUC at the same time. 

 

 

 

 

 

 

 

 

[zlymex]

.........

What's the difference in charging time with a 4A charger? I'm guessing about double a 2A charger?

Plus, how powerful can I go before it's bad for my High Speed 850wh Gotway?

 

Thanks.

The charging time for an empty 850Wh would be 3.6 hours for 4A charger theoretically . However, there is a balancing circuitry in each pack and it only functioning when nearly full. It is suggested that 1 or 2 more hours charge is needed once the charger light turns green from red. 

The fastest speed I rode my MS model without fall is around 36km/h(app speed). 
For HS model, here is the graph of one of my friends. The average speed is 30.36km/h(true GPS speed) and the max. speed is about 36km/h.
App speed is 12% larger than GPS speed from my estimate.

[MetricUSA]

Very weird they can't get the speed number right, must fugded in a large diameter wheel in the softwear...

[Ben Ryan]

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. 

Hi, you maybe able to help me. I have  unicycle that is still brand new in the box and battery is not working. Is there any chance.. of reviving these batteries?

[marc]

Hi, you maybe able to help me. I have  unicycle that is still brand new in the box and battery is not working. Is there any chance.. of reviving these batteries?

You can open the case. and look if the voltage of each battery cell is between 3.6-4.2 Volt. Maybe there are dead cells. If the battery management system is not from good quality one dead cell can make the system fail. If only this cell is replaced, the problem would be resolved. If the problem is in the cabling between batteries and motor, you can check it by sending a current through the cables. All of this can be done by a multimeter which costs 3 dollar nowadays.

[Ben Ryan]

thanks for the advise Marc

[Cranium]

On 10/14/2015, 12:04:07, zlymex said:

 

I know I'm resurrecting an old topic here but it was referenced from another thread concerning the battery cells and this picture caught my attention.

It appears that you set the load tester to a constant voltage of 60V and measured the current output at that voltage.  And at this voltage, you got the pictured 2.842A.  

If this is the case, then I can understand why you thought the chargers were no good.  These chargers are Constant Voltage (CV) and Constant Current (CC) chargers if I understand them correctly.  When charging a battery it will be in CC mode when then voltage is below the rated voltage and will shift to CV mode once it reaches the rated voltage.  This means if you put the load tester to 0V, you should see the full 5A output from the power supply.  But at 60V, it has started to shift to the CV mode and has reduced the current.

Of course, all of this has many assumptions since I am going off of a single picture with no background of how you actually did the test.  If my assumptions here are way off, I apologize in advance.

 

[esaj]

Here's a graph made from Charge Doctor output while charging 3 * 192Wh packs with the original Firewheel charger, as you can see, the charge current won't start to drop until the peak voltage has already been hit:

The axes are a bit messy, as there's large gap between the values (left-hand -side is voltage in volts, around 56 to 67.8V, and current, in 100's of milliamps going from a little over 2 amps to few tens of milliamps, right-hand side is watthours). Actually the casing of the Firewheel charger says 1.75A, but still it outputs around 2A.

Not sure if other chargers could behave differently, I've always thought the charging is controlled by the BMS and the chargers are just "dumb" (switching?) power supplies?

[Cranium]

Good graph!

It shows exactly what I was talking about but from a power supply side.  And it makes sense that there is control in the BMS as well since they do have circuitry to prevent overcharging.  The chargers also have circuitry to limit and monitor current.  They won't deliver more than their rated current (short protection) and they change from a red LED to green LED when charging current goes below 100mA or so.

I've ordered a set of the charging plugs for my Ninebots.  I will be using these to hook up a test to my load tester to test the charger.  

 

[esaj]

24 minutes ago, Cranium said:

The chargers also have circuitry to limit and monitor current.  They won't deliver more than their rated current (short protection) and they change from a red LED to green LED when charging current goes below 100mA or so.

True, of course the chargers must limit the current too... I think the light changed green on the Firewheel charger around 250mA charging current, but it could still take about an hour for it to drop all the way to 0mA (with the original 2 * 132Wh packs). I think that the cell-balancing is done only at the very end of the charging, ie. it could start going only after the light is already green? Usually the BMS-spec sheets list fairly low currents for balancing...

 

Quote

I've ordered a set of the charging plugs for my Ninebots.  I will be using these to hook up a test to my load tester to test the charger.  

These were some Lemo-plugs right? Would you mind posting the correct types / part numbers if you happen to know them (male / female), hobby16 was looking for the input-plug in the summer (although I think he found the right part after we found out the correct "general" name for the plugs ) so he could make Ninebot-versions of Charge Doctor.

[Cranium]

 

50 minutes ago, esaj said:

I think that the cell-balancing is done only at the very end of the charging, ie. it could start going only after the light is already green? Usually the BMS-spec sheets list fairly low currents for balancing...

If it is like RC chargers, the cell balancing will occur throughout the charging process and possibly even when not charging.  But, as you pointed out, the balancing currents are very low.  

 

52 minutes ago, esaj said:

These were some Lemo-plugs right? Would you mind posting the correct types / part numbers if you happen to know them

You are correct with the Lemo-plugs.  I saw many options (including nicer metal casings) but the ones here seemed to be the right match for what is there with the plastic plugs. I got this link from another thread here a few weeks ago.  

[zlymex]

On 2015/12/5 at 1:12 AM, Cranium said:

I know I'm resurrecting an old topic here but it was referenced from another thread concerning the battery cells and this picture caught my attention.

It appears that you set the load tester to a constant voltage of 60V and measured the current output at that voltage.  And at this voltage, you got the pictured 2.842A.  

If this is the case, then I can understand why you thought the chargers were no good.  These chargers are Constant Voltage (CV) and Constant Current (CC) chargers if I understand them correctly.  When charging a battery it will be in CC mode when then voltage is below the rated voltage and will shift to CV mode once it reaches the rated voltage.  This means if you put the load tester to 0V, you should see the full 5A output from the power supply.  But at 60V, it has started to shift to the CV mode and has reduced the current.

Of course, all of this has many assumptions since I am going off of a single picture with no background of how you actually did the test.  If my assumptions here are way off, I apologize in advance.

 

Ideally, the V-I curve of a 5A charger can be depicted as the green lines on the pic below. The horizontal line is the constant current part which stays at 5A no matter what the output voltage is(within 57.2V limit, not the rated 60V). This part can be tested by electronic load with CV mode.
Green vertical line is the constant voltage part which stays at 67.2V no matter what the output current is(within 5A limit). This part can be tested by electronic load with CC mode.
The green curve is so called two-stage charger and is very similar to normal CV-CC power supply output.

Often there exists a three-stage charger which gives small current output when battery is low as depicted in the dotted green lines.

For a normal good charger(red lines), because of the internal resistance(wires, battery etc.), the current start to fall at 66V to 66.5V instead of 67.2V.

As for that 5A poor charger, open output voltage is only 56.2V(blue lines). Not only the current at 60V is small, but the open voltage is also much lower than 67.2V

 

 

Edit: the orange curve is the actual test for my 2A charger come with IPS 122.
I've bought another 5A charger and is still on the way. I'll test it when it arrives.