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Serious Accident


Citi Wheel

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On ‎1‎/‎4‎/‎2016 at 2:49 AM, lizardmech said:

I'm very skeptical that they can dissipate the heat they produce with their current designs.

I was thinking about this recently after reading that the KS 16 has a cooling fan. I hope that's a robust fan, since I've seen too many power supply fans and video card fans fail in computers. I wonder why EUCs don't have vents or holes to let more heat out.

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2 hours ago, MaxLinux said:

I wonder why EUCs don't have vents or holes to let more heat out.

Dust and moisture would enter into the control board. It's a trade-off situation.

The KS16 fan according to many reports (including mine) is doing a good job, will see after time...

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@MaxLinux @lizardmech

I wonder if just adding a fan is going to cut it. The wheel's in motion at up to 30kmh this builds up pressure, directs flow, etc.

Like in a computer server, some forced directional flow would be much better, but with an EUC it's much more complex

-  you can drive the wheel in 2 directions

- air inflow: on both "front" sides?, on the side? (high up?, what with IPS rating?), avoiding road dust with a filter? (maintenance?)

- air outflow: how hot (not to where the legs are)? to the bottom?

- a powerfull fan uses a lot electricity

Natural air flow induction when riding probably is a good way to go (which means airtunnel testing, and a more robust approach to IPS rating the electronics), and once you stand still a powerfull fan to reduce the heat build-up.

 

@MaxLinux @lizardmech

I wonder if just adding a fan is going to cut it. The wheel's in motion at up to 30kmh this builds up pressure, directs flow, etc.

Like in a computer server, some forced directional flow would be much better, but with an EUC it's much more complex

-  you can drive the wheel in 2 directions

- air inflow: on both "front" sides?, on the side? (high up?, what with IPS rating?), avoiding road dust with a filter? (maintenance?)

- air outflow: how hot (not to where the legs are)? to the bottom?

- a powerfull fan uses a lot electricity

Natural air flow induction when riding probably is a good way to go (which means airtunnel testing, and a more robust approach to IPS rating the electronics), and once you stand still a powerfull fan to reduce the heat build-up.

 

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Transporting the heat to an exposed heatsink is easy, you only need a small hole for heat pipes to fit through. Not at all difficult to keep it waterproof. The KS16 seems to have a hole where the metal heatsink sits so it has some exposure to the outside air, but it probably only has much impact at low ambient temperatures.

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 @logos122 i did not even know that you crashed?!

I hope you have a good recovery and everything gets good again....

 

As there have been some discussions about wearing protections at all(  @Keith will be my witness) and some members represented their opinion that shut off's or sudden fall's could be "rolled off" by ease from a "trained"or "used to it" unicycler and some even just see no use of protections until our EUC's have reached 50kmh or more......

 

I can only say to all EU-Cyclers: Read These story's here...logos122 is one of the longer riding members....even @EUC Extreme with the best protections you can have, has now got some metal in his shoulder.... They both have NONE Chance to react on their Crashs....

 

Absolut!!! Minimum and only for very slowly test riding should be: Knee pads, Wrist guards.......for gliding out some  falls you can not run off....

But Best should be: Knee Pads, Elbow protection, Wrist guards AND Helmet....if not even more if you go for a fast and fun ride or offroad!

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  • 2 months later...
On 04/01/2016 at 8:36 AM, lizardmech said:

It would depend on many variables. With a light rider on flat ground you might be using on average 250-300 watts cruising along, assuming the fets are maybe 97% efficient leaving you with 3w or so of heat, maybe the sealed compartment can shed 1 watt of heat but it probably takes 12 hours to get anywhere near overheating.

The problem is when you throw in other variables, you get a heavier rider equipped with a large battery pack who's trip starts with him climbing a 2km hill. He burns through 2kw of continuous output for a few minutes climbing it at 20-30 km/h the heatsink is now dealing with 50w+ of heat but has no way of removing it. He gets to the top of the hill and continues his ride across flat ground, problem is the heatsink and mosfets are now at 80C or so, the mosfets are now less efficient due to heat and close to failure temperature. The mosfets are now adding more than normal amounts of heat to the heatsink which doesn't even have a way to remove the heat from the hill climb, then the mosfets just continue to get less efficient until they fail. If they don't fail the heatsink will probably melt some other component when it gets around 100C.

When I deal with mosfets on computer voltage regulation dealing with continuous 300watts+ with only passive cooling is impossible. You have to cool them with large heatsinks and fans or water cool them. Even when the mosfets can withstand 130c the rest of the board rarely does. I have never had a single properly cooled mosfet fail on any computer component I have ever owned, so it's abnormal if they are regularly failing on EUCs.   

Why, don't the EUC manufacturers use fan based cooling as well as passive cooling. It would seem to make sense...

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5 hours ago, charlie - uk said:

Why, don't the EUC manufacturers use fan based cooling as well as passive cooling. It would seem to make sense...

For a fan to cool effectively, you need two holes in the case to circulate outside air. Those holes can let water and dirt get into the circuit board area. Plus the fan itself is a moving part and will be affected by dirt and water. 

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  • 2 months later...
On 1/4/2016 at 1:01 AM, logos122 said:

A week ago I was riding to work on my msuper2. I don't actually remember this, I just remember waking up in the hospital on Christmas Eve. I ended up breaking my clavicle and hitting my head in the accident. I am now having some memory issues and will likely need surgery for the clavicle. Everyone be warned, always be prepared for an electric unicycle to cut out on you and wear wrist guards and a helmet at a minimum.

I believe I was able to piece together what caused the accident. I haven't ridden the Gotway for a while after the accident, but recently my friend and I were trying it out. We noticed that the unit started shaking violently at speed, but we were not sure what the cause was. My friend took it to a car shop and they saw there was looseing where the pedals connect to the axel. After tightening it up, the shaking stopped. So in the end, it was probably not a cut-out that caused the accident, as I had originally thought. My friend had the same loosening issue with his msuper2, as have other people on youtube. 

Please check you EUC to make sure this does happen to you.

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13 hours ago, logos122 said:

............. there was looseing where the pedals connect to the axel. After tightening it up, the shaking stopped. So in the end, it was probably not a cut-out that caused the accident, as I had originally thought. My friend had the same loosening issue with his msuper2, as have other people on youtube. 

 

This is an very important piece of information. However, because I cannot see video on youtube, can you attach a photo to indicate which part is loosening. Is that the joint between the pedal and the post, or the post to axis?

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11 hours ago, zlymex said:

This is an very important piece of information. However, because I cannot see video on youtube, can you attach a photo to indicate which part is loosening. Is that the joint between the pedal and the post, or the post to axis?

I will post a picture

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  • 3 weeks later...
On 10/30/2016 at 4:31 PM, logos122 said:

 

Please check you EUC to make sure this does happen to you.

So it was just a question of tightening the bolts on each side? What was the piece that fell out there?

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1 hour ago, Shoe73 said:

So it was just a question of tightening the bolts on each side? What was the piece that fell out there?

That's one of the metal wedges that binds against the shaft to hold it tight. 

At around 7 minutes into this video, you'll see what it's about. 

 

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