My Sherman Trials, Tribulations, and Triumphs

[Planemo]

The manufacturers should simply take a completely different look at this situation. I appreciate that in general there is only so long that something can last at max power, but we are so far from that scenario it's not funny. Work out how much power the batteries can supply and the motor can take, then design and build your hardware around that. Massive PA sound systems don't meltdown after 10 seconds at max volume, road cars and motorbikes don't self destruct in minutes at full speed, you just need to build your design with enough headroom. Yes we can argue that Overheat Hill to some would seem 'outside of operating design parameters' but I would disagree. Road vehicles are tested to extremes of temperature and conditions for extended periods before making it to production, a failure on a steep hill is not acceptable IMO. If a person can physically ride it, the EUC should take it.

As I say, I appreciate that everything has a limit, I would not expect an EUC to make it to the top of mount Everest, but I do expect more than a couple of minutes. If they cant manage to make the hardware, stop putting out wheels with such monstrous battery and motor specs because it becomes pointless. No, I would never tackle anything like overheat hill but given the destruction seen there after such a short period of time, I cant help but wonder how much heat would be generated at extended 40+mph rides (which I may do if I had a Sherman).

These EUC manufacturers need to employ someone from Tesla, Marshall Amps or hell even the Eurostar to understand how to heat manage and build headroom. Failing that, simply stop making wheels where two thirds of the wheel is capable of 5x what the other third can take.

[FullTilt]

10 minutes ago, Planemo said:

. Failing that, simply stop making wheels where two thirds of the wheel is capable of 5x what the other third can take.

 

[Planemo]

Brilliantly accurate 

[Chriull]

1 hour ago, Planemo said:

I cant help but wonder how much heat would be generated at extended 40+mph rides (which I may do if I had a Sherman)

At 64+ km/h (40+ mph) the motor already generates noticable voltage. If the lift cut off speed is somewhere about ?100 km/h?(1), This would be about 100.8V / 100km/h * 64km/h~64V!

So by the "reduced" voltage difference of 100.8V-64V~47V between battery and motor only "reduced" max current can flow! 

At the speed the motor produces only 6.8V (~7 km/h if my lift cut off assumption is right) the voltage difference between battery and motor is twice as high and so twice the max current could flow!

And cooling by air drag gets better at high speeds, too.

But still with 47V difference at 64km/h by the batteries pack internal resistance of only ~0.1Ohm and a motor coil resistance in about this range some whooping max current in the range of roughly 200A could flow!

Edit: rethinking this i assume/hope the motor has a "higher" coil resistance as such currents get too high for to247 package limits.... ..although after the overheat hill test most legs of the mosfets were gone, so who knows...

So maybe time for some volunteer to find an high speed overheat hill! 

1 hour ago, Planemo said:

These EUC manufacturers need to employ someone from Tesla, Marshall Amps or hell even the Eurostar to understand how to heat manage and build headroom. Failing that, simply stop making wheels where two thirds of the wheel is capable of 5x what the other third can take.

Although heat managment/design should have enough possibilities  for improvement, these burdens cannot be handled within the size of an EUC.(2)

So imho the only feasable solution for this should be wisely placed temperature sensors and according power throttling in firmware. 

Allowing some short time peak burdens and warn in time before throttling occurs.

Identifying the weakest spots, monitoring their temperature and simulating near future burden in firmware is no rocket science...

(1) likely even higher? Have no real idea and did not find numbers googling...

(2) the battery packs already have a power dissipation of ~4kW delivering 200A...

Edited July 17, 2020 by Chriull

[Patton250]

2 hours ago, Planemo said:

The manufacturers should simply take a completely different look at this situation. I appreciate that in general there is only so long that something can last at max power, but we are so far from that scenario it's not funny. Work out how much power the batteries can supply and the motor can take, then design and build your hardware around that. Massive PA sound systems don't meltdown after 10 seconds at max volume, road cars and motorbikes don't self destruct in minutes at full speed, you just need to build your design with enough headroom. Yes we can argue that Overheat Hill to some would seem 'outside of operating design parameters' but I would disagree. Road vehicles are tested to extremes of temperature and conditions for extended periods before making it to production, a failure on a steep hill is not acceptable IMO. If a person can physically ride it, the EUC should take it.

As I say, I appreciate that everything has a limit, I would not expect an EUC to make it to the top of mount Everest, but I do expect more than a couple of minutes. If they cant manage to make the hardware, stop putting out wheels with such monstrous battery and motor specs because it becomes pointless. No, I would never tackle anything like overheat hill but given the destruction seen there after such a short period of time, I cant help but wonder how much heat would be generated at extended 40+mph rides (which I may do if I had a Sherman).

These EUC manufacturers need to employ someone from Tesla, Marshall Amps or hell even the Eurostar to understand how to heat manage and build headroom. Failing that, simply stop making wheels where two thirds of the wheel is capable of 5x what the other third can take.

You make an interesting point. I have a question for you. My Mercedes-Benz has a six cylinder TwinTurbo engine in it. It can go 190 mph give or take 5 mph. Let’s say I find a spot where I can go that fast for as long as I want. How long do you think that car could go 190 mph before something catastrophic would happen to the engine? Do you feel the German engineers knowing the made it able to go 190 mph they also should have designed the car to be able to go that fast indefinitely? 

Edited July 17, 2020 by Patton250

[travsformation]

13 hours ago, Shield said:

Isn't that a bit reductionist? No one here is hating on the Sherman, if we hated it we wouldn't be participating in this discussion, which is focused on finding the weak points so they can be addressed and the Sherman can become the (near) perfect wheel we all want it do be.  

I think you're mistaking hating with being critical of what ones loves, the purpose of which is to be able to love this wheel with all our might, without holding back and no nagging "but it..." or "what if..." in the back of our mind. Tough love is still love 

Or maybe I'm just reading too much into a meme. Am a bit sleep-deprived these days...😅

Edited July 17, 2020 by travsformation

[travsformation]

2 hours ago, Planemo said:

The manufacturers should simply take a completely different look at this situation. I appreciate that in general there is only so long that something can last at max power, but we are so far from that scenario it's not funny. Work out how much power the batteries can supply and the motor can take, then design and build your hardware around that. Massive PA sound systems don't meltdown after 10 seconds at max volume, road cars and motorbikes don't self destruct in minutes at full speed, you just need to build your design with enough headroom. Yes we can argue that Overheat Hill to some would seem 'outside of operating design parameters' but I would disagree. Road vehicles are tested to extremes of temperature and conditions for extended periods before making it to production, a failure on a steep hill is not acceptable IMO. If a person can physically ride it, the EUC should take it.

As I say, I appreciate that everything has a limit, I would not expect an EUC to make it to the top of mount Everest, but I do expect more than a couple of minutes. If they cant manage to make the hardware, stop putting out wheels with such monstrous battery and motor specs because it becomes pointless. No, I would never tackle anything like overheat hill but given the destruction seen there after such a short period of time, I cant help but wonder how much heat would be generated at extended 40+mph rides (which I may do if I had a Sherman).

These EUC manufacturers need to employ someone from Tesla, Marshall Amps or hell even the Eurostar to understand how to heat manage and build headroom. Failing that, simply stop making wheels where two thirds of the wheel is capable of 5x what the other third can take.

 

[Shield]

.

Edited July 20, 2020 by Shield
Irrelevant Drivel

[Patton250]

1 hour ago, travsformation said:

 

I’m thinking why don’t you guys get together and purchase one of these companies? I’m getting the feeling that you could make these wheels infinitely better than Inmotion, Gotway and King Song. 

[Planemo]

2 hours ago, Patton250 said:

How long do you think that car could go 190 mph before something catastrophic would happen to the engine?

A helluva lot longer than our EUC's do at full power output that's for sure.

It's this headroom that I am talking about. The same headroom that Toyota built into their own 6 cylinder twin turbo engine. The same one I modified to twice it's original power and still ran the stock crank/rods/pistons/oil pump/bearings in fact the entire bottom end. For many 1000's of miles.That's headroom.

[Patton250]

1 minute ago, Planemo said:

A helluva lot longer than our EUC's do at full power output that's for sure.

It's this headroom that I am talking about. The same headroom that Toyota built into their own 6 cylinder twin turbo engine. The same one I modified to twice it's original power and still ran the stock crank/rods/pistons/oil pump/bearings in fact the entire bottom end. For many 1000's of miles.That's headroom.

I don’t know. LOL. It’s an interesting question. It seems some of you guys think the Mercedes should be able to go 190 mph for as long as you want it to go that fast. Maybe it can for all I know. I’m too scared to find out. :-)

[Planemo]

20 minutes ago, Shield said:

I am not trying to start anything, I just fail to understand the need for some to point out flaws on a wheel they have no intention of getting in order to feel better about the one they did get. 

I'm not sure if that's aimed at me or not because I will happily point out the flaws in my MSX and believe me theres plenty of them  My issue with underrated or simply woeful hardware is aimed at most if not all the manufacturers at the moment. What has prompted me to flag up the Sherman is simply because its the best example out there of having hardware which is nowhere near up to par of the batteries and motor. All manufacturers have the same problem albeit to varying lesser degrees.

[Planemo]

3 minutes ago, Patton250 said:

 It seems some of you guys think the Mercedes should be able to go 190 mph for as long as you want it to go that fast. 

I don't know where you got that from. I thought I made it clear that I didn't expect a Veteran to get to the top of Everest and my comment "I appreciate that in general there is only so long that something can last at max power " I do however expect it to get to the top of a hill. So what I expect from the manufacturers is somewhere inbetween those scenarios. Pick any point

[Shield]

6 minutes ago, Planemo said:

I'm not sure if that's aimed at me or not ...

No, it wasn't. 

[Patton250]

7 minutes ago, Planemo said:

I don't know where you got that from. I thought I made it clear that I didn't expect a Veteran to get to the top of Everest and my comment "I appreciate that in general there is only so long that something can last at max power " I do however expect it to get to the top of a hill. So what I expect from the manufacturers is somewhere inbetween those scenarios. Pick any point

I totally agree with that

[Hansolo]

7 hours ago, Chriull said:

As  @Alj wrote insulation will be needed, too! Some ceramic/mica plates. And don't forget insulation for the screws.

If this is made in a proper way it will increase the burden the wheel can take, but for sure not make it safe for all "possible burdens"

 

I tested with ceramic plates (a resistance in TO220), with thermal grease in addition it is much more efficient than the original silicone pad.

But I did not equipp my motherboard because the ceramic is britter and I fear that during a fall ...

[winterwheel]

This is *the site* for discussing points, good and bad, of every aspect of wheeling, including the features and faults of new wheels. 
There are other places to go to for those who want to hold hands and sing com-by-yah 24x7.

 

[Chriull]

10 minutes ago, Hansolo said:

But I did not equipp my motherboard because the ceramic is britter and I fear that during a fall ...

It's fixed between the mosfet body and the heatsink - i could not think of anything that could happen?!

[Boogieman]

18 hours ago, travsformation said:

That makes a lot of sense, looking at that re-fried, charcoal-grilled board. But why did some MOSFET connection points burn and others didn't? 

 

The capacitor that shorted probably drives the row of mosfets that ALL burnt (legs burnt off).

The capacitor that DID NOT short, probably drives the other stack of mosfets that were all fine.

[erk1024]

17 hours ago, Alj said:

Any design has a bottleneck somewhere. Ideally this bottleneck should be just user, but that is not something you can control, so once user is out of question you just want this bottleneck to be in a proper place. From what it seems the bottleneck appear to be in heat dissipation (very bad place) and they are moving it to a software (better place, but seems not ideal). What other choices they have? Lets see:

I guess it's just time for Veteran to make their lower speed High Torque Wheel. Gotway MSX --> MSP.  Veteran Sherman --> ??? 

[Marty Backe]

1 hour ago, Boogieman said:

The capacitor that shorted probably drives the row of mosfets that ALL burnt (legs burnt off).

The capacitor that DID NOT short, probably drives the other stack of mosfets that were all fine.

From memory, maybe 1 or 2 of the 12 MOSFET didn't have their legs burned off. So you're observation about the capacitor is wrong 

[erk1024]

Something to keep in mind is that Gotway, Kingsong, InMotion and now Veteran (LeaperKim whatever) are all small entrepreneurial companies. The one big company, Segway/Ninebot has stopped making new wheels in favor of going after a more lucrative market: scooters. These companies don't have big budgets for R&D, testing, or long, mature development cycles. The wheels are one step removed from being prototypes. The benefit of this approach is rapid innovation. The downside is possibly product reliability.

The hope is that as the community grows, the companies will grow with it, and with the community's input the products will improve. And they HAVE improved. Just look at wheels from a few years ago. Boosted arguably made the best electric skateboards, and they just went out of business. Ninebot has essentially abandoned us. We're lucky that a handful of companies are willing to work in this risky, niche market. And of course we should keep pushing for fixes and improvements.  

 

Edited July 17, 2020 by erk1024

[Bvoland]

45 minutes ago, erk1024 said:

Something to keep in mind is that Gotway, Kingsong, InMotion and now Veteran (LeaperKim whatever) are all small entrepreneurial companies. The one big company, Segway/Ninebot has stopped making new wheels in favor of going after a more lucrative market: scooters. These companies don't have big budgets for R&D, testing, or long, mature development cycles. The wheels are one step removed from being prototypes. The benefit of this approach is rapid innovation. The downside is possibly product reliability.

The hope is that as the community grows, the companies will grow with it, and with the community's input, the products will improve. And they HAVE improved. Just look at wheels from a few years ago. Boosted arguably made the best electric skateboards, and they just went out of business. Ninebot has essentially abandoned us. We're lucky that a handful of companies are willing to work in this risky, niche market. And of course we should keep pushing for fixes and improvements.  

 

I have been watching this thread going all over the place and I have been hoping that someone would bring up these exact points. I am happy that Veteran has pushed the envelope and I am sure they will continue to make improvements and this will help push the other companies forward. It would be unfortunate especially in the current environment if they all went out of business and we are looking for a new hobby.

[Planemo]

1 hour ago, erk1024 said:

Something to keep in mind is that Gotway, Kingsong, InMotion and now Veteran (LeaperKim whatever) are all small entrepreneurial companies. The one big company, Segway/Ninebot has stopped making new wheels in favor of going after a more lucrative market: scooters. These companies don't have big budgets for R&D, testing, or long, mature development cycles. The wheels are one step removed from being prototypes. The benefit of this approach is rapid innovation. The downside is possibly product reliability.

I don't think anyone is under any illusion that the majority of wheels are made by small backstreet companies. Hence the issues. I'm certainly not surprised at the hardware issues, doesn't mean I am happy with it, or indeed that I will expect it will get sorted anytime soon. It is what it is.

24 minutes ago, Bvoland said:

 It would be unfortunate especially in the current environment if they all went out of business and we are looking for a new hobby.

Never going to happen. The Chinese found money in wheels many years ago when virtually zero people were buying them. The market has only got bigger since, and will continue to do so. That's not to say some won't fold (Boosted for example) but there will be many more waiting in the sidelines.

[Ben Kim]

8 hours ago, Patton250 said:

You make an interesting point. I have a question for you. My Mercedes-Benz has a six cylinder TwinTurbo engine in it. It can go 190 mph give or take 5 mph. Let’s say I find a spot where I can go that fast for as long as I want. How long do you think that car could go 190 mph before something catastrophic would happen to the engine? Do you feel the German engineers knowing the made it able to go 190 mph they also should have designed the car to be able to go that fast indefinitely? 

The engine would throw a light and go limp if something went awry which would still enable you to stop and operate the vehicle in a limited state; something a self balancing PEV doesn’t have the luxury of doing. 

You can’t make an EUC go into limp mode on failure because it’s simply the way these things are designed. When you have an EUC with no limits it is up to the user to determine what those limits are and ride accordingly. For everyone else, there’s Kingsong and Inmotion. 

Edited July 17, 2020 by Ben Kim