ElectricMotorcycleForum.com

Been thinking about this ... I can't quite see how the size of the rear pulley affects the force on the belt. The force is converted to a simple linear tension force by the front pulley, and this reaches the rear pulley the same no matter how big it is. The load is then spread out over the edges of all of the teeth on the rear pulley until it exits at the bottom. The only factor affecting the force experienced at the rear is the size of the front.

Cas

You are right, the size of the rear sprocket on its own doesn't contribute to the force in the belt (at least not from motor torque), however if the system is designed to have about the same ratio as the original gearing, when you make the rear sprocket larger, the front sprocket gets larger too to maintain the same ratio.  And since the peak motor torque will be the same regardless of the sprocket size, the larger front sprocket will impart less force into the belt that a small sprocket, therefore under that assumption, a larger rear sprocket will result in less force in the belt. Example if the motor does 100Nm a sprocket with 50mm radius will result in 2000N in the belt (100Nm / 0.050m = 2000N), if you reduce the front sprocket size to 40mm radius (also adjusting the rear sprocket to be smaller to maintain the same front:rear ratio)  the force goes up to 2500N in the belt when the motor is delivering 100Nm.

That said, the same math is true for when the rear wheel imparts force into the belt through its sprocket, a larger wheel sprocket will impart less force into the belt when the wheel tries to accelerate the motor.  This is easiest to visualize by picturing what happens when the wheel lifts into the air while on throttle. In the air, the wheel will accelerate quite quickly as there is no longer any force from the road preventing the wheel acceleration, then when the wheel hits the ground again the tire's surface speed could be much faster than the ground speed, and the force of the wheel contacting the ground could be high resulting in excellent traction to slow that wheel back down to ground speed very quickly and as the wheel slows down it will create a force in the belt to slow the motor down too. That, combined with the motor probably still delivering forward torque from throttle demand results is a significant shock load and force to the belt.  Also, when the swingarm goes through its travel the belt will also cause the motor to rotate, typically that doesn't cause much motion (the amount of rotation will be approximately equal to the rotation of the swingarm around its pivot), and the nature of the physics around that motion (mainly due to suspension) tends to restrict the motor acceleration caused by suspension travel, so it is generally not a belt design consideration.

-ryan

I had a similar thing occur on my 2013 XU in around 2019.  I think I tracked the problem to the inline fuse / fuse holder that goes from the battery (low power B+) to the DC-DC.  From what I remember I removed the fuse, cleaned the fuse and fuse holder with contact cleaner, then reassembled it and haven't had the problem since.

So are these Caofens real or vaporware?

I think they have been marketed in several different ways, none of which seem to have got much traction:
Caofen F80
Horwin HT5
Ox DUK
GoTrax Everest (supposed to be available at Best Buy)
and the latest is Dimen Dimentro DT ( https://thepack.news/eicma-e-news-dimen-tech-will-present-their-new-subsidiary-e-brand-dimentro/ )

Thanks a lot...
70Nm seems plausible for a M10/10.9 screw. But that torque is very high for an HX6 allan key. Not sure if my PROXXON tool can handle that. So, first I will order a HAZET 986SLG-6. (But always better to damage the tool, as damaging the screw :-))

I think Loctite arround the shaft makes only sense with the "keyed" version of the pulley. It have the pulley with the "teeth" arround the shaft, from 2017 on. Hopefully without Loctite. If so, it would make no sense for me.

Think a "impact screwdriver" is also not a good option cause of the encoder magnet,- rotor magnets, right?

Will see...

The pulley with the teeth (splined shaft) is glued on , it will require fire application along with a gear or bearing pulling tool to remove without damaging the motor.

Are you able to share a photo of the damage to the motor pulley?

-ryan

It really depends on how much power / torque you are talking about, and what kind of traction control system will be implemented.  If you aren't pushing the limits of traction in most conditions issuing equal torque commands to front and rear motors is probably going to work out just fine.  Where you get into trouble is when you are climbing a steep hill (which gives the rear wheel much better traction) and are turning a corner where you need the front wheel to set your course,  if you apply too much torque to the front wheel and it starts slipping just to maintain straight travel, you will have very little control to initiate a turn and could lose balance.  If you are just making a utilitarian vehicle where you want to get the best traction in all cases and maybe the front spins and looses traction sometimes, but isn't that big of deal because you are going slow enough that you just put your feet down to prevent a fall,  like the Ubco 2X2 , you can probably just give equal torque commands to the front and rear and hope for the best.

-ryan

Quote from: Crissa on March 29, 2021, 12:02:38 PM

Because a 14-50 only does 50a.

Only?  What vehicle has an AC charger of more than 12,000 watts (240VAC times 50 amps=12,000 watts)? But perhaps there is a Tesla 14 KW out there as 14KW destination charge stations do exist.

That is what makes J-1772 so stupid, IMO. Unnecessary limitations, IMO. Most of them are probably fed using a 50 amp (or more) source.

Yeah, they need the pilot because of the limitations of it that would NOT be there if the J-1772 didn't exist at all and we could simply get to what is feeding it.

IOW, tell the J-1772 that your 12 KW vehicle AC charger  can only accept  6.6 KW because the J-1772  is only capable of 6.6 KW. But if the J-1772 didn't  exist you could then get the full 12KW. That's what makes J1772 so stupid, IMO.

Notice Tesla Destination did NOT go that stupid route and they have  14KW AC stations all over. The nice thing is that even our Zeros can use them with an adapter. None of that needing two charge stations BS. Doesn't  matter what Telsa or non-Tesla is using it, get up to 14KW, at least with some. And that is fine even with your bike. It will only draw what your bikes AC charger  is capable of. No need to tell a 14-50R (or whatever)  anything.

BTW, I am not sure if any Teslas have a 14KW AC charger. I have not yet heard of such, but I do wonder why some of the Tesla Destination stations  are 14KW of AC capable.


-Don-  Reno, NV

Don, I agree that replacing  J1772 stations with NEMA 14-50 plugs would be good for some people.  The problem is that like Carissa indicated using J1772 makes things more compatible.  A lot of the J1772 stations aren't capable of 50A, I would say most of them aren't, so that basically ends the conversation about replacing J1772 stations with 14-50 plugs.   Requiring that every charging station has 50A capability, and access to reset the breaker if it trips, is cost prohibitive. A lot of places have shared stations, so if only one charger is being used, you get 32A,  if the other station nearby starts getting used, your current will drop to 16A, and the other station will use 16A too.  You can't do that without some sort of communication, and for better or worse, the industry has determined that J1772 is the standard. 

-ryan

As far as traveling and providing your own energy, it is possible to do on a motorcycle, you just need to consider average power consumption, and power production.  Typically an electric motorcycle is about 100Wh/mile, so you go about 10miles per kWh, if you travel around 45-55mph.  or 10kWh will get you about 100miles.  If you have good sun and a 1kW solar array (I think that would be a reasonable size to be able to store and transport in a motorcycle trailer) you might be able to travel 100miles every couple days.  I think a 1kW wind turbine would probably be too awkward to transport, but also I think wind is even less predictable than sun, and in some places you simply wouldn't have wind to charge.

If you are interested in "travel on solar power" check out these adventurers:
https://www.routedelsol.com/
their youtube channel: https://www.youtube.com/channel/UCEqGj33c8pwpcjiT093W-5A/featured

Watching through their content you will learn a lot about what it takes to travel on solar power.  I think the number one take away I got is don't plan too far ahead because most likely nothing will go to plan, and just enjoy the journey, because the journey is going to take a long time.
-ryan

motorcycles are light, so the total amount of energy to move the bike up the hill is typically insignificant.  If the destination is 1000m (3300ft) higher than the starting point, that is  300*9.8*1000 = 2.94MJ of energy (about 0.8kWh) assuming total bike+rider weight is 300kg (660lbs)  Assuming 85% efficiency of converting battery energy to potential gravitational energy, that would use about 0.94kWh of battery to lift the bike up that evlevation change, so it takes such a large hill to become significant. 

Assuming going down the hill to the beach you "recover" potential energy at 100% efficiency, the difference of battery usage to get down the hill vs going up the hill would be about 1.75kWh. So if you make it to the bottom of the hill with 1.75kWh left in your battery, and you charge up to full while you are there, you should be able to make it back traveling at the same speed.  If you have less than 1.75kWh when you get to the bottom of the hill, you will want to travel up the hill more slowly than you came down, to spend less energy moving the air around you.

Again, that assumes a 1km (3300 foot elevation change). Also note this calculation assumes the elevation at the start and the end of the trip,  any increase / decrease in elevation between those two points roughly balances out and doesn't influence energy consumed that much (as long as you have enough energy to make it to the top of the highest point between the start and end).

Another thing to consider is prevailing winds and air temperature, which will both affect aerodynamics.  I believe typically, winds blow off the ocean, so you may have a prevailing tail wind going up the hill, since the bottom of the hill is a beach.  A 7-10kph wind can have significant impact on your range, especially if it is against you going one way, and with you going the other.  Also air temperature has a significant impact on range,  a study I read about bicycle racing and the effect of temperature on aerodynamics suggest that for every 10C temperature increase, the aerodynamic drag decreases by 3%.  And depending on your speed, the most significant influence is your riding position.  If you need to extend your range by 10-15% you can simply tuck to reduce your total cross section area,  the faster you go the more tucking will affect your range.

If you want an adventure, go for it, do some math to prepare yourself to adjust your riding style if you find it necessary, and have a backup plan should things not work out the way you hoped. Without adventure life is boring.

-ryan