Future EUC Wishlist

[Nic]

4 minutes ago, Planemo said:

Standard charge rate for Sanyo NCR18650GA is 1,67A. So even at 10A charge, the MSX used in the example is within manufacturers charge recommendations.

Point being, 10A isn't even 'fast charge', it's 'standard' charge.

This isn't an answer ... its just you making your point ... point taken.

[Mono]

1 minute ago, Planemo said:

Standard charge rate for Sanyo NCR18650GA is 1,67A. So even at 10A charge, the MSX used in the example is within manufacturers charge recommendations.

Point being, 10A isn't even 'fast charge', it's 'standard' charge.

I was surprised, but in the above linked article 1h30 (0.67C) seems still to count under fast charging with damaging effects on the battery. But then, never trust a single news article.

[Planemo]

6 minutes ago, Nic said:

https://www.theregister.co.uk/2019/06/05/liion_battery_scan_charging/

 

Sure, the batteries are getting bigger, but the miles per watt-hour is still roughly the same so an hour on a slow charger might be enough to make sure you can make it home. This is better than not having a charger don't you think?

You already explained that you don't need a built-in slow charger, that is fine. Others may have a different view. We don't all have to agree on what we would like to see on our wishlist.

Make it home, maybe. But a 1 hour charge at 1.5A would mean such a low mile per watt-hour return that you could probably walk it anyway. And in less time than the 1 hour you spent charging. And your point would assume you had the charge lead with you. I guess I am saying that I would just plan things better or have a bigger capacity wheel.

I am not saying we all have to agree, far from it. I am just putting my point across, as you did yours.

 

[Planemo]

4 minutes ago, Nic said:

This isn't an answer ... its just you making your point ... point taken.

I wasn't trying to answer anything. Just letting you know that in our MSX example, charging at 10A is within manufacturers spec. Thats not my point, thats fact, and won't damage the cells as you suggested it would.

Not sure why you seem to be taking offence at everything I post so I will bow out of this one now.

[Mono]

17 minutes ago, Nic said:

What additional costs? A simple board that is easily replaced would probably cost less.

I assume that a charger that is highly reliable under strong mechanical distress is much more expensive than one which shows low reliability even without any mechanical distress. I don't know any specifics.

17 minutes ago, Nic said:

And why not both?... built-in slow charger plus external port for fast charge?

Cost and weight are the two disadvantages which come immediately in my mind. While being on the disadvantages, the necessary cable will also be a constant point of annoyance for sure.

I also don't like to always carry chargers, but that is how it seems to be for all portable devices, namely phones and computers and EUCs. I have the feeling that there must be some good reasons for why this is so?

Edited November 18, 2019 by Mono

[Nic]

18 minutes ago, Planemo said:

Make it home, maybe. But a 1 hour charge at 1.5A would mean such a low mile per watt-hour return that you could probably walk it anyway. And in less time than the 1 hour you spent charging. And your point would assume you had the charge lead with you. I guess I am saying that I would just plan things better or have a bigger capacity wheel.

I am not saying we all have to agree, far from it. I am just putting my point across, as you did yours.

 

My v8 can fully charge in 4.5 hours and its range lets say is 14 miles. I can go visit a friend 10 miles away and watch a movie and chat while I put some charge in to get me home. Or if I already have enough charge, I can have extra miles to take the scenic route home.

 

10 minutes ago, Mono said:

I also don't like to always carry chargers, but that is how it seems to be for all portable devices, namely phones and computers and EUCs. I have the feeling that there must be a good reason for why this is so?

Maybe its because many devices now charge using USB port and charging points can be found almost everywhere as many people have phones and computers as well as USB chargers. One day maybe we will be in the same position with chargers for PLEVs.

Edited November 18, 2019 by Nic

[Nic]

10 minutes ago, Planemo said:

I wasn't trying to answer anything. Just letting you know that in our MSX example, charging at 10A is within manufacturers spec. Thats not my point, thats fact, and won't damage the cells as you suggested it would.

Being within specification says nothing about cycle life other than this will meet the specifications under those conditions.

Edited November 18, 2019 by Nic

[atdlzpae]

49 minutes ago, Nic said:

You do realise that the datasheet says nothing about cycle life for different charging rates? ... its just data for discharge rates.

It's actually the worst case scenario, essentially if you ride like crazy maniac, always discharge until the wheel cuts off on you to 0% and always fast-charge to 100%.
And even if it's 82% after 6000km, I'll be happy.
 

25 minutes ago, Nic said:

What additional costs? A simple board that is easily replaced would probably cost less.

You can McGuyver an external charger for your unicycle for $20 even in the most remote town in Syberia.
Hell, taking 5 laptop chargers, removing ground and connecting them in series to make 90V would charge a unicycle.
An internal charger would cost $200 to replace because it's made by Gotway... It wouldn't be any smaller. And be at a risk of getting wet in the rain.

[Nic]

12 minutes ago, atdlzpae said:

It's actually the worst case scenario

Only under the stated conditions.

[mike_bike_kite]

Is it worth getting back on topic?

I was finding the future ideas quite interesting.

[soundkite]

Built in motion and tamper alarm.  EUCs already have the gyroscopes to detect movement, so seems like a no brainer to me.  Also, I need some sort of key to render my EUC useless.

[Mono]

2 hours ago, Nic said:

Maybe its because many devices now charge using USB port and charging points can be found almost everywhere as many people have phones and computers as well as USB chargers.

All of these devices came with a charger long before USB even existed or public charging points were a thing.

[Nic]

11 minutes ago, Mono said:

All of these devices came with a charger long before USB even existed or public charging points were a thing.

I think I may have misread your post ... its because of USB that you now don't always need to carry a separate charger with you for many (low powered) devices. Separate chargers are no longer supplied with many of these and often they just come with a charging cable.

[Mono]

That would suggest the trend going even further away from an onboard charger. Just put 2 USB-C ports which then can be used for both, charging the wheel and charging any other device from the wheel?

[Nic]

18 minutes ago, Mono said:

That would suggest the trend going even further away from an onboard charger. Just put 2 USB-C ports which then can be used for both, charging the wheel and charging any other device from the wheel?

Ultimately yes, but EUCs are not quite ubiquitous yet. The idea was to achieve the same degree of freedom until we get there.

Edited November 18, 2019 by Nic

[xorbe]

USB-C is only rated to 20V@5A peak though.

[Shad0z]

9 hours ago, Nic said:

Who said anything about destroying the battery? And is this just your 'opinion' or do you have some figures to back up your assertions? Current is what causes heat and that is greater when fast charging is it not? Are you certain 100% that your battery is perfect? Does it remain in perfect condition throughout its life? If everything is so great with fast charging they why isn't this the new normal? Some facts please. 

If you read the battery spec sheets. You will see that these batteries can take a lot of current. Fast charging is definitely not a new thing lol

[zeke]

About the fast charging debacle debate...

Going down a steep hill at speed, regen charges the cells faster than any fast charger on the market. For example, a 100kg rider+EUC descending at 1m/s (corresponding to 20km/h down a 10% grade) will generate 1kW, approximately 250W of which will go to drag and other loss and the remaining 750W into charging the battery. By contrast, most of the fast chargers provide <500W. So if you're concerned about battery health, descending long steep hills at speed should be your first point of concern.

The main reasons for not integrating a fast charger into the EUC would be its cost, size, weight, and reliability. Some of us wouldn't mind that, some of us would.

Maybe the best compromise would be if these chargers could be attached outside the shell of the EUC, with a slick compartment to stow the cable. Then you could leave it attached during all your casual rides and plug in wherever you found yourself.

[Nic]

50 minutes ago, zeke said:

About the fast charging debacle debate...

Going down a steep hill at speed, regen charges the cells faster than any fast charger on the market. For example, a 100kg rider+EUC descending at 1m/s (corresponding to 20km/h down a 10% grade) will generate 1kW, approximately 250W of which will go to drag and other loss and the remaining 750W into charging the battery. By contrast, most of the fast chargers provide <500W. So if you're concerned about battery health, descending long steep hills at speed should be your first point of concern.

The main reasons for not integrating a fast charger into the EUC would be its cost, size, weight, and reliability. Some of us wouldn't mind that, some of us would.

Maybe the best compromise would be if these chargers could be attached outside the shell of the EUC, with a slick compartment to stow the cable. Then you could leave it attached during all your casual rides and plug in wherever you found yourself.

I never said I was against fast charging ... only that it isn't the best for batteries. If there is no demand to have a built-in charger then the manufacturer won't bother. With a 1600Wh battery it becomes less of an issue, so maybe its best for cheaper small battery EUCs rather than the larger battery enthusiast models? No point in beating a dead horse.

Incidentaly, how did you arrive at those numbers for regen?

[zeke]

20 minutes ago, Nic said:

I never said I was against fast charging ... only that it isn't the best for batteries. If there is no demand to have a built-in charger then the manufacturer won't bother. With a 1600Wh battery it becomes less of an issue, so maybe its best for cheaper small battery EUCs rather than the larger battery enthusiast models? No point in beating a dead horse.

Incidentaly, how did you arrive at those numbers for regen?

Downward force of gravity F = mg = 100kg × 9.8m/s² = 980N.

Power is the product of force and velocity (at least, the component of velocity that is parallel to the force). Assuming 1m/s downward descent rate, the power being extracted from a the rider's descent P = Fv = 980N × 1m/s = 980W ≈ 1kW. A rider traveling at 20km/h is traveling at 5.6m/s, so a descent rate of 1m/s means the grade is arcsin(1m/s ÷ 5.5m/s) = 10.4% grade. 

According to this online calculator, a bicyclist traveling at 20km/h dissipates ~180W into drag. I'll just hand-wavy bump it up to 250W because EUC riders are more upright, EUCs have more rolling resistance, and there's some efficiency loss in the motor drive circuit.

So net resulting power that must be absorbed by the battery is ~750W.

[zeke]

3 minutes ago, zeke said:

Downward force of gravity F = mg = 100kg × 9.8m/s² = 980N.

Power is the product of force and velocity (at least, the component of velocity that is parallel to the force). Assuming 1m/s downward descent rate, the power being extracted from a the rider's descent P = Fv = 980N × 1m/s = 980W ≈ 1kW. A rider traveling at 20km/h is traveling at 5.6m/s, so a descent rate of 1m/s means the grade is arcsin(1m/s ÷ 5.5m/s) = 10.4% grade. 

According to this online calculator, a bicyclist traveling at 20km/h dissipates ~180W into drag. I'll just hand-wavy bump it up to 250W because EUC riders are more upright, EUCs have more rolling resistance, and there's some efficiency loss in the motor drive circuit.

So net resulting power that must be absorbed by the battery is ~750W.

Oops, I meant to say degrees instead of % grade. The angle of inclination is 10.4°.

1m/s downward velocity out of 5.6m/s total velocity corresponds to a 1m/s÷5.5m/s = 18.3% grade.

 

Nonetheless, I'm sure you can find scenarios where you can exceed this level of regen power.

[xorbe]

Why don't wheels use resistive forces instead when the battery is greater than 90% full?  (ie, coils open, then close and pull the magnets back after passing.)  Just like changing direction, I mean.

Edited November 19, 2019 by xorbe

[Mono]

1 hour ago, zeke said:

Nonetheless, I'm sure you can find scenarios where you can exceed this level of regen power.

Or it might be that the controller limits the regen current. Not at all unlikely, IMHO.

Edited November 19, 2019 by Mono

[Mono]

36 minutes ago, xorbe said:

Why don't wheels use resistive forces instead when the battery is greater than 90% full?

How do you know what the wheels do (not) use (it's a serious question)? We have reasonably good evidence that wheels not only do regen braking. To my understanding in particular for hard braking, the current flow is reversed.

Edited November 19, 2019 by Mono

[Nic]

1 hour ago, zeke said:

Downward force of gravity F = mg = 100kg × 9.8m/s² = 980N.

Power is the product of force and velocity (at least, the component of velocity that is parallel to the force). Assuming 1m/s downward descent rate, the power being extracted from a the rider's descent P = Fv = 980N × 1m/s = 980W ≈ 1kW. A rider traveling at 20km/h is traveling at 5.6m/s, so a descent rate of 1m/s means the grade is arcsin(1m/s ÷ 5.5m/s) = 10.4% grade. 

According to this online calculator, a bicyclist traveling at 20km/h dissipates ~180W into drag. I'll just hand-wavy bump it up to 250W because EUC riders are more upright, EUCs have more rolling resistance, and there's some efficiency loss in the motor drive circuit.

So net resulting power that must be absorbed by the battery is ~750W.

Interesting ... shouldn't the downward force due to gravity for 10 degree slope be the vertical component of F = m * g * Sin(slope) = 100kg * 9.8m/s² * sin(10^o) = 170N

Therefore P = FV = 170N * 1m/s = 170W that is available for regen.

I'm not sure if this is correct, but it seems more reasonable to me as my bicycle brakes don't catch fire when going down hill.

Edited November 19, 2019 by Nic