Samsung cell options: 40T, 50E, 50S, etc

[InfiniteWheelie]

It’s ridiculous that electric skateboards all use high power cells, yet it’s been uncommon for electric wheels despite needing it for safety more than any other PEV. However simply having more power isn't the full solution...

What I want to see are wheels which are virtually impossible to overpower. Of course no matter how powerful the wheel, they can all be overpowered by exceeding the top speed or accelerating too hard at high speed. The solution is to create the most powerful wheel possible, then hard capping the top speed below what it's capable of.

I think 100 km/h would be a good cap for the following reasons... 1: Very few people want or need to ride any faster. 2: It's fast enough to ride with traffic on any non-freeway road. 3: Due to the exponential nature of air resistance, you won't be able to go much faster anyway, especially while keeping enough headroom to eliminate overpower situations (2x speed = 8x power).

Let's look at the math. The Samsung 50S is rated for 5c continuous, which equals 18 kW for 3600 Wh wheels. 100 km/h requires roughly 13 kW, so we’re good there. However bumps, low battery, cold, headwinds, hills, and hard acceleration at high speeds can all cause much higher peaks. That said, cells can also peak much higher for short durations. As you can see, we're within the ballpark of making this happen.

By using high power cells, combined with slightly larger batteries/motors/controllers, we should be able to create a wheel that's virtually impossible to overpower up to 100 km/h. Of course the exact speed cap could be slightly higher or lower, 100 km/h just happens to be a nice round number which is towards the upper limit.

Edited December 3, 2023 by InfiniteWheelie

[Panzer04]

On 12/2/2023 at 11:34 PM, InfiniteWheelie said:

It’s ridiculous that electric skateboards all use high power cells, yet it’s been uncommon for electric wheels despite needing it for safety more than any other PEV. However simply having more power isn't the full solution...

What I want to see are wheels which are virtually impossible to overpower. Of course no matter how powerful the wheel, they can all be overpowered by exceeding the top speed or accelerating too hard at high speed. The solution is to create the most powerful wheel possible, then hard capping the top speed below what it's capable of.

I think 100 km/h would be a good cap for the following reasons... 1: Very few people want or need to ride any faster. 2: It's fast enough to ride with traffic on any non-freeway road. 3: Due to the exponential nature of air resistance, you won't be able to go much faster anyway, especially while keeping enough headroom to eliminate overpower situations (2x speed = 8x power).

Let's look at the math. The Samsung 50S is rated for 5c continuous, which equals 18 kW for 3600 Wh wheels. 100 km/h requires roughly 13 kW, so we’re good there. However bumps, low battery, cold, headwinds, hills, and hard acceleration at high speeds can all cause much higher peaks. That said, cells can also peak much higher for short durations. As you can see, we're within the ballpark of making this happen.

By using high power cells, combined with slightly larger batteries/motors/controllers, we should be able to create a wheel that's virtually impossible to overpower up to 100 km/h. Of course the exact speed cap could be slightly higher or lower, 100 km/h just happens to be a nice round number which is towards the upper limit.

The issue is you can't hardcap wheel speed. If it were so simple, Manufacturers would hardcap wheel speeds below the cutout point. Instead, they resort to beeps and tiltback, but neither is really sufficient to guarantee no overspeed cutouts. If the user keeps leaning forward, there's not that much you can really do. In practice, I suppose wind resistance might get high enough you'd have to be leaning so low to keep pushing it that you simply can't accelerate?

I suppose it might technically be possible if the tiltback is aggressive enough, so that it's not physically possible to lean forward, but I wonder how safe such a thing would be. In the future it will most likely be more of the same - tiltback, beeps, and increasing power/top speed so that the wheel is capable of going faster than people are comfortable actually riding.

Edited December 3, 2023 by Panzer04

[WheelGoodTime]

A big "thank you" to Jason @ eWheels for commissioning a lab to do the tests on the 50S batteries and providing the results, and thanks to those here who provided the other info and useful graphs which show the 50S compared to other battery types.

 

Edited December 3, 2023 by Rfail1988

[InfiniteWheelie]

@Panzer04 Those are all good points I've also considered, and I agree.

By capping top speed I do mean tilt-back. Sure you may be able to push past, but you'll definitely know you're doing so. Currently we have to be careful when approaching the top speed, both in terms of acceleration and surpassing it (setting lower PWM limits does help).

With high power cells, we should be able to keep the same top speed as the fastest wheels now (or slightly higher) without tip toeing while approaching it. You could simply accelerate as hard as possible right until you feel the top speed tilt-back, with plenty of spare power and time to backoff. The goal I'm advocating for is to have more torque than you’re able to use within the capped speed. I think that's probably possible with speeds up to 100 km/h, which would cover 99% of riders and roads. Even if that number turns out to be only 80 km/h, so be it. I want safety and peace of mind above absolute top speed.

Sure, in theory there may be a point where wind resistance limits even the best riders from leaning any harder to gain speed, but battery technology isn't there yet.

Edited December 4, 2023 by InfiniteWheelie

[dimos15]

10 hours ago, Panzer04 said:

I suppose it might technically be possible if the tiltback is aggressive enough, so that it's not physically possible to lean forward

This is possible , freestyler did some tests with a custom firmware. I might have the videos , if you want i will search for them. He found out that with high capacity batteries like the 50e you have to use the tilltback at low pwm for someone to not overpower it . I think it was 70% or 60%. This is another reason why we need high discharge batteries. With high discharge batteries you are actually using less pwm at the same speed because they sag less

[InfiniteWheelie]

@dimos15 I’d like to see that if you can find it. Having tilt-back that you can’t overpower is a major plus for safety. Especially because alarms can be unreliable. It’s possible to not hear the beeps coming from the wheel itself, or if using an app, there are many points of possible failure (bluetooth disconnection, app crash, phone/earbuds die etc).

———————————————

After reflecting upon my earlier posts, I’ve realized that in practice, wheels with much higher power would still fundamentally function the same as they do now. Rather than a hard speed cap like I described, they’d still have adjustable PWM tilt-back, which could still be set near 100% to achieve the true top speed if desired. The real differences are: 

• You could choose to set the PWM much lower for the same top speed (larger safety margin).

• You’d be able to maintain much higher speeds on low battery.

• Huge torque increase, which could give you virtually unlimited usable torque up to a high speed. In fact, it seems that no wheel is currently capable of this at any speed. From what I’ve seen, Adam from WrongWay has been able to dip every wheel he’s ridden, even at the lowest speeds. Imagine a wheel that no matter how hard you jerk or lean, cannot be overpowered up to a very high speed (outside of extreme combinations of inclines/headwinds).

Edited December 5, 2023 by InfiniteWheelie

[dimos15]

On 12/5/2023 at 6:19 AM, InfiniteWheelie said:

@dimos15 I’d like to see that if you can find it. Having tilt-back that you can’t overpower is a major plus for safety.

 

You can find most of the videos in these two threads

Edited February 7 by dimos15

[dimos15]

So i heard that the new leaperkim wheels charge their battaries above 4.2 volts per cell. Is it true?

I found a nice video that explains why high nickel batteries like the 50s degrade faster when you charge them at 100%+

We need an option to start balancing before 4v per cell like kingsong and i think inmotion have

 

Edited February 7 by dimos15

[I2x2]

If you had a choice which battery would you run on a master v4 : p42a molice or a 50s?

[KAY GEE]

1 hour ago, I2x2 said:

If you had a choice which battery would you run on a master v4 : p42a molice or a 50s?

P45B...... 👍

[macgyvercanada]

Quote

So i heard that the new leaperkim wheels charge their battaries above 4.2 volts per cell. Is it true?

Seems to be; I've seen some screenshots showing over-charge.  I'd love to see software-based charge limiting like most electric cars seem to have.  Notionally, I'd limit charging to 70% and try to keep the charge above 30% to prolong battery life, but every cell type has different thresholds.

[Panzer04]

On 4/3/2024 at 12:19 AM, I2x2 said:

If you had a choice which battery would you run on a master v4 : p42a molice or a 50s?

Honestly, 50s is a great compromise. Wheels don't regularly hammer the batteries at 3C/8kw or more, usually it's a brief spike up to that sort of power draw. I suspect that overall the great capacity of the 50s and correspondingly higher voltage towards the end of the discharge will probably result in better overall performance.

Between P45A and 50S it's 50S no question IMO.

[alcatraz]

I think it depends on the rider weight and climate. If you're heavier and/or riding in hot temperatures then choose a cell that can handle higher current.

For lighter riders in moderate climate they can ride those 50E cells for an eternity without issues.