My Sherman Trials, Tribulations, and Triumphs

[EUChristian]

11 hours ago, Chriull said:

Yes - that was one translation i used googling and dictionaries which meant something different than i meant. Your explanation of cogging torque is nicely explaining it's meaning and showing it's irrelevance here. As it is also described as "no current torque" in the second link of my post - i wanted to remove it than from my post but forgot this before submitting it...

As described (or at least how i understood it) in the first paper i linked, the main portion of "torque ripple" comes from the current changes by the different commutation phases. By the difference in the commutation pattern and the back emv of the motor (winding characteristics). Of course this "maladaption" is proportional to the value of the phase current.

Just "measured" the main harmonics of @Marty Backe's last bit of hill climbing - seems to be at ~150Hz. Taking the formula (6) from the paper 

"f i th = i*k*p*n/ 60 (6) where th i f is the th i order harmonics of the motor commutation frequency, i is the number of the harmonics order, k is the number of steps of commutation in one electrical cycle, p is the number of stator pair of poles, and n is the rotational speed (r/min). In the CV-mode and VV-mode k = 6. Thus, the fundamental commutation frequency 1 th f is 0.1pn ."

gives for the veteran (54 coils -> 27 pole pairs, 20 inch tire ~ 1.6 m circumference) for 150 Hz as the first harmonic 55 rpm ~ 1,5 m/s ~ 0,4 km/h.

Which seem to fit quite well with the video.

The "150 Hz" are, for me surprisingly high - i would have estimated the frequency much lower. As the "stuttering noises" while hard acceleration and braking. Some years ago this stuttering noise while acceleration was explained from a gotway representative to arise from their ?120 A? firmware current limiting. Will have to measure such stuttering braking noise once too if this corresponds to the "main torque ripple" frequency - current limiting occurs "within the commutation pattern" and hence increase the maladoption or sets in independently...

Edit: .... And this numbers could be just about fitting but are maybe just some "initial starter". Just looked at the video linked in https://forum.electricunicycle.org/topic/18545-tesla-motor-noise-and-battery-charge-questions/ . Here by a loose motherboard caused oscillation of about 120 Hz. And @Marty Backe reported some strange vibrations of this wheel before. Something a bit loose caused vibrations (oscillations) via the gyro sensor... Beeing stimilated/induced by torque ripple?

 

 

I believe you 100% since I have zero clue what you are talking about. 

[Violinfun]

Vee's review video is only other one I have seen that has the same grinding noise appear briefly.   It was also struggling to get up a hill.  I am somewhat surprised at this being a weakness of this wheel given the pedigree of the engineers and the success of some of the Gotway hill climbing wheels.  Or is it just an issue of the unit being too heavy for the engine?

 

[Marty Backe]

4 minutes ago, Violinfun said:

Vee's review video is only other one I have seen that has the same grinding noise appear briefly.   It was also struggling to get up a hill.  I am somewhat surprised at this being a weakness of this wheel given the pedigree of the engineers and the success of some of the Gotway hill climbing wheels.  Or is it just an issue of the unit being too heavy for the engine?

It's not the weight of the wheel. 220 pound guys can ride up very steep hills on the MSP, a much lighter wheel, without the same struggles.

The motor/control board are tuned for speed not torque.

[Violinfun]

12 minutes ago, Marty Backe said:

It's not the weight of the wheel. 220 pound guys can ride up very steep hills on the MSP, a much lighter wheel, without the same struggles.

The motor/control board are tuned for speed not torque.

OK that makes sense.  I was seeing they sold speed vs torque versions of the msp's.  Are all the differences just firmware or is physical engineering differences between the two types of EUC's?  I'm just waiting on the Shermans to arrive at eWheels..impatiently.  I am just hoping I won't have issues around Atlanta which is a surprisingly hilly city.

[Marty Backe]

19 minutes ago, Violinfun said:

OK that makes sense.  I was seeing they sold speed vs torque versions of the msp's.  Are all the differences just firmware or is physical engineering differences between the two types of EUC's?  I'm just waiting on the Shermans to arrive at eWheels..impatiently.  I am just hoping I won't have issues around Atlanta which is a surprisingly hilly city.

The motors are physically different. Not just (if any) firmware.

Seriously, the Sherman was beautiful on all the mountain roads that I was riding (climbing 6000-feet - do you have those in Atlanta?). I contend that there will be zero issues even with the current design on any roads traveled by cars. Just don't use it on 4x4 type roads 

[MrRobot]

What speed will we be able to charge first batch wheels up to? 

Edited July 28, 2020 by MrRobot

[Marty Backe]

43 minutes ago, MrRobot said:

What speed will we be able to charge first batch wheels up to? 

I don't understand the question 

[MrRobot]

I see reports saying that the first batch will only have two wires per charging port and will be upgraded to 4 wires on later batches to handle higher amps. 

So what's the most amps you can charge up to on the first batch with two wires? And can the ports be upgraded relatively easily to 4 wires by end users? 

[Will R]

3 hours ago, MrRobot said:

I see reports saying that the first batch will only have two wires per charging port and will be upgraded to 4 wires on later batches to handle higher amps. 

So what's the most amps you can charge up to on the first batch with two wires? And can the ports be upgraded relatively easily to 4 wires by end users? 

2 wire versions can charge at 8A per port, 10A maximum. 4 wire versions can charge at 10A per port, still with 10A maximum. The only difference is the 4 wire versions can be charged at 10A without needing to use a port splitter. For the sake of 10 bucks for the port splitter, just get one and leave it on and you won't need to rip the wheel apart to replace the ports. They would be relatively straightforward to replace however if you really wanted to; plenty of people have done it with their GWs, just make sure to use the correct charger or you've made a bomb!

[Marty Backe]

13 hours ago, MrRobot said:

I see reports saying that the first batch will only have two wires per charging port and will be upgraded to 4 wires on later batches to handle higher amps. 

So what's the most amps you can charge up to on the first batch with two wires? And can the ports be upgraded relatively easily to 4 wires by end users? 

According to the manual, the Sherman can be charged at 10-amps. It doesn't say explicitly but I assume the intention is to use one 5-amp charger for each charging connector. So if you had a single 10-amp charger then I would use a splitter.

If you wanted to upgrade the charging connectors, it's doable but will require a lot of work. You'll have to remove the control board which means totally disassembling the Sherman (including splitting the shell).

[FreeRide]

22 hours ago, Marty Backe said:

According to the manual, the Sherman can be charged at 10-amps. It doesn't say explicitly but I assume the intention is to use one 5-amp charger for each charging connector. So if you had a single 10-amp charger then I would use a splitter.

If you wanted to upgrade the charging connectors, it's doable but will require a lot of work. You'll have to remove the control board which means totally disassembling the Sherman (including splitting the shell).

Can you check with Veteran or ewheels, there was a message in another thread quite a while ago that said that although they had 2 charge ports, the max charge current was in fact only 8A.  I believe ewheels was quoted in the message specifically saying not to plug in two 5A chargers.   Maybe there was some miscommunication, but it would be good if the next time you talked with them you could confirm.

[Violinfun]

9 hours ago, FreeRide said:

Can you check with Veteran or ewheels, there was a message in another thread quite a while ago that said that although they had 2 charge ports, the max charge current was in fact only 8A.  I believe ewheels was quoted in the message specifically saying not to plug in two 5A chargers.   Maybe there was some miscommunication, but it would be good if the next time you talked with them you could confirm.

FWIW, the guy from Speedy Feet (Ian I think) who just finished the 1k review of the Sherman has stated that he charged it with two 5 amp chargers without issue.

[HippoPig]

Just wondering if the current numbers etc mean anything to anyone on here.

Honestly - not sure what it should be generating (max momentary I guess), what it can take and what to look out for in my data.

 

We stopped for coffee with a friend and left the Gps running 🤷🏼‍♂️ Used darknessbot.

 

Edited August 1, 2020 by HippoPig

[Delmeekc]

Marty, what's the current status of the Sherman unless I missed it. You was waiting for 2 control boards. Have you got them, have you tested them and are you going to revisit overheat hill with both?

Edited August 13, 2020 by Delmeekc
Site duplicated text three times.

[null]

He is waiting for a new motor as the cables startet melting.

[zege]

I am also a bit concerned, is the Sherman maybe of lesser interest to you @Marty Backe after the over heat hill test failing and after you have tried riding V11 seated? Many many thanks for all your great videos over the years btw!

Edited August 13, 2020 by zege

[Marty Backe]

8 hours ago, Delmeekc said:

Marty, what's the current status of the Sherman unless I missed it. You was waiting for 2 control boards. Have you got them, have you tested them and are you going to revisit overheat hill with both?

 

7 hours ago, null said:

He is waiting for a new motor as the cables startet melting.

 

7 hours ago, zege said:

I am also a bit concerned, is the Sherman maybe of lesser interest to you @Marty Backe after the over heat hill test failing and after you have tried riding V11 seated? Many many thanks for all your great videos over the years btw!

 

New control board installed and a new motor installed. The wheel works, but I then discovered that the LCD panel was also destroyed on Overheat Hill.

I can ride the Sherman but cannot configure it or monitor the status. Tilt-back is stuck at 18-mph so the wheel isn't very usable.

Waiting for a new LCD panel to be sent from Veteran.

[Delmeekc]

1 minute ago, Marty Backe said:

 

 

 

New control board installed and a new motor installed. The wheel works, but I then discovered that the LCD panel was also destroyed on Overheat Hill.

I can ride the Sherman but cannot configure it or monitor the status. Tilt-back is stuck at 18-mph so the wheel isn't very usable.

Waiting for a new LCD panel to be sent from Veteran.

Pretty bad then for the hill. Hope it all gets sorted ready for another test. Did you ever find out what the difference is on the two control boards.

[Marty Backe]

Just now, Delmeekc said:

Pretty bad then for the hill. Hope it all gets sorted ready for another test. Did you ever find out what the difference is on the two control boards.

No, they never told me 

But the new motor looks great 

[Delmeekc]

1 minute ago, Marty Backe said:

No, they never told me 

But the new motor looks great 

That's a bit shite, so you have to try both and not know what the difference may or may not be.

[Marty Backe]

2 minutes ago, Delmeekc said:

That's a bit shite, so you have to try both and not know what the difference may or may not be.

At this point I have no intention of trying the 2nd board unless I'm given a compelling reason to do so. Changing the board on the Sherman entails a complete tear-down of the wheel.

[Delmeekc]

1 minute ago, Marty Backe said:

At this point I have no intention of trying the 2nd board unless I'm given a compelling reason to do so. Changing the board on the Sherman entails a complete tear-down of the wheel.

Flip a coin then for which one to install.

[Marty Backe]

1 minute ago, Delmeekc said:

Flip a coin then for which one to install.

Oh, the wheel is already rebuilt. I'm waiting for the new LCD Panel.

They did tell me which board to use first. I just don't know why 

Edited August 13, 2020 by Marty Backe

[Shield]

41 minutes ago, Marty Backe said:

No, they never told me 

But the new motor looks great 

What is the difference between the new and old motor? I hear there were changes.

Edited August 13, 2020 by Shield
Grammar

[.....]

On 7/17/2020 at 3:42 PM, Marty Backe said:

Absolutely. I'm still first in line to get a Sherman. Absolutely fantastic wheel, in broad strokes. I've learned that it won't be the best for hilly off-road riding (which I suspected from the beginning) but it's great for cruising and more mellow off-road adventures.

This is what i needed to hear. This wheel is planned to be a street cruiser/mile eater for me. At such a weight, I had no intention of making it into anything offroad, more than a leisure climb. So long as Veteran puts throttling or warning in it, that save the hardware, I can be okay with having to stop and rest on tough climbs. I can also be okay with not flying at speed up the mountain. Sustained higher speeds on a typical street with standard road inclines is my concern. I'd imagine the speed aids in cooling. Since the NYC boys are speed demons and some weigh more than I, my preorder is still safe. Exciting wheel with a likely chance I won't be upset. I honestly think that my plans for this wheel are within what they intended it to do. Hope springs eternal anyhow. Hey Veteran: Double check mine to see that it at least has the screws in it, that you designed it to hold.

Edited August 13, 2020 by ShanesPlanet