S18 - only 45km range? Last 30% only last 5km!?!

[reach]

Hi,

Today I rode my S18 for the first time from 100 to 0% battery. As much as I love the S18 this was a very disappointing experience:

not having a battery indicator, after some 35km I checked the app for the first time, just out of curiosity and was pretty shocked to see only 47% left. 

5km later, after 40km I reached 30% battery and it started to beep and tiltback constantly and early. Apparently it beeps also when I'm going slow, as a reminder. After 44km I was at 15% and some 500m later it was at 5%. It tilted back until I stopped. When holding the wheel on the handle it slowly, really slow motion tilted forward and backward and forward and backward. Even while walking it. I shut it down, switched it on again and then I could continue to ride home the missing 300m at walking pace with the wheel constantly peeping.

Back home I waited 1 hour before I plugged in the charger. Before that I checked the battery with the app and it said not 5, but zero %(!!) 

When plugging the chanrger, it threw an error, saying the voltage is too low. Luckily it charged nevertheless and now it seems to be fine.
(I'm using the eunicycles smart charger which has its own webserver)

I weigh 80kg and I had an average speed of 22km/h - which is more than it sounds. I was pretty much going as fast as I could all the time (however, I'm not so skilled, so I have limited it to 46km/h and for sure I can't use all it's acceleration potential eiher)
My Inmotion V11 reaches easily 90km without throtteling. I never drove it past that, but it seems to reach easily its specified range.

So my question is: is this normal?? Both, the disappointing range and the ridiculously and dangerously fast battery drain after 30%?

Edited June 12, 2022 by reach

[Funky]

Seems kinda low.. And definitely odd behavior.

Try charging to 100%. When it get's to 100% plug in "original" charger. Keep charging for 1-2hrs more. And repeat the test.

Does the "smart" charger automatically stop(turn off) charging, when it gets to 100%? Or does it keep charging. (If it goes off right at 100%, you don't really balance the cells..) So might be ducked up batteries. Ofc i'm just guessing.. It shows 84V at 100%?

How old is the wheel, mileage?

Also which battery pack it has? New one or old one?

[meepmeepmayer]

Hard to say if it is normal or odd.

45km from 1110Wh and fast riding... sounds very plausible.

And voltage goes down fast near the end. I consider 30% (at rest) nearly empty because then the beeps start as soon as you push a little. Your 65.85V is 3.2925V per cell, and 3.3V is a typical 0% voltage. So far, so normal.

The percentage drop near the end seems very sudden, though.

28 minutes ago, reach said:

My Inmotion V11 reaches easily 90km without throtteling.

Now that is the real surprise here! 90km from 1500Wh? Did you ever ride it as fast as the S18?

[reach]

10 minutes ago, meepmeepmayer said:

Now that is the real surprise here! 90km from 1500Wh? Did you ever ride it as fast as the S18?

Can't say, currently it's broken, again, and still waiting for the spare part from China.
I also mostly rode it "as fast as I can". However, the S18 provided so much more confidence from the first second onwards, that I reached higher speeds and slopes than I ever did with the V11. Still, I think in terms of range the difference in riding style should be negligible.

So, when you say this sounds reasonable, is this just paper figures, or also your personal experience?

15 minutes ago, Funky said:

How old is the wheel, mileage?

Also which battery pack it has? New one or old one?

The wheel is brand new, battery has maybe 4 cycles. In Europe we only have one type of battery pack, so that's what I have. 1110 Wh

You seem to distrust that charger. Fair point. I think it's really good. It charges fast up to a adjustable threshold and then slow. Wheel was connected mayn more hours after reaching 100%. Also the app confirmed 100%. So, despite the appropriate doubts, I'd rule out the charger. (I don't have the original one. If you go for the smart one, eunicyles swaps them before shipping)

[Funky]

24 minutes ago, meepmeepmayer said:

Now that is the real surprise here! 90km from 1500Wh? Did you ever ride it as fast as the S18?

On my 18xl i get 50km and battery is at 50% 72-73V. And i weight 127kg, so for lighter rider maybe it's possible.  

Heck my dad weights 70kg and on his ks16s he can do over 50km. On one charge 840mah battery pack. < He rides 15x times more than me..

Edited June 12, 2022 by Funky

[meepmeepmayer]

47 minutes ago, reach said:

Can't say, currently it's broken, again, and still waiting for the spare part from China.

47 minutes ago, reach said:

So, when you say this sounds reasonable, is this just paper figures, or also your personal experience?

Going around 30kph (beeps at 35) on my 1300Wh ACM, I (80-85kg on the pedals) get about 55-60km (Wheellog distance) before the annoying beeps start, which I consider the end. So getting 45km on a much faster wheel with 1110Wh seems not out of the ordinary. (The ACM ends at 3.3V per cell, too, just like the S18 apparently does.)

Whether the rapid percentage (and voltage?) drop at the end is normal, I can't say. Would not surprise me, with the "small" (3p) battery, but might not be normal as well. Someone with an S18 must say.

Don't ever believe manufacturer range claims, these are pure fantasy.

46 minutes ago, Funky said:

On my 18xl

Yea the 18XL gets a lot of range. Part of that is that it has 3V per cell as 0% voltage, part of that might be the relatively sluggish firmware (I rode it and found it a bit sluggish, so this is subjective), and part of that might just be magic.

You guys must be going slow for these ranges, though. 50km on a 16S? Not bad! (Though, with lower weight, the range rises surprisingly rapidly.)

Edited June 12, 2022 by meepmeepmayer

[The Brahan Seer]

The range you experience is reasonable. Bear in mind the battery capacity is 36% less than your V11.  It does throttle you down from 30% onwards. Which is normal and the limitations of this wheel unfortunately unless you use Molicel 42A or equivalent batteries. Of course the range will vary a lot due to weight, speed, incline, decline, temperature, and wind. If you are street or off roading too. Obviously the more opportunity it gets to regenerate the greater the range.  Now you understand the expectation of the wheel hopefully you can enjoy it more. 

[Funky]

17 minutes ago, meepmeepmayer said:

You guys must be going slow for these ranges, though. 50km on a 16S? Not bad! (Though, with lower weight, the range rises surprisingly rapidly.)

Dad rides at 30kph.(He rarely goes to 30.. because no gear..) I at ~35kph my alarm is set at 40kph.  

Edited June 12, 2022 by Funky

[Whalesmash]

At my weight of 145 pounds geared (66kg), I have managed to smoke my S18 battery in 28 miles (40km) on a trail run I did a few weeks ago. Off the top of my head, I also had a street commute that was 17 miles (27km) that took the battery from 85% down to 17%. It is important to take into considering other factors that were at play during your ride as the others mentioned, but that being said, your numbers are possible though definitely on the lower end. 

[RetroThruster]

I've yet to get an S18 to charge to 100% so consider yourself lucky (both molicel), just getting my money back if they'll return my email...

[Ksmack]

I’ve got the S18 Molicel version. I’ve ridden it down to 0% battery before pushing it pretty hard. I get about 8.5km from 30% to 0%. From 100% (what the KS app reports) to 30% I get 39.5 km. For most of this trip I rode at 23-29mph. This works out to about 49 km total riding pretty hard on streets. There were some big hills involved as well. I’m about 195lbs with gear. 

[reach]

Molicell is this special battery which only the US importer offers, right? I guess that's not compareable, but thanks anyway - your numbers are indeed similar to mine.

Two more questions: 

1) check out those screenshots from today's ride. Here you see how quickly it drains in the end. Essentially, the wheel isn't really usable any more after reaching 30%. It throttels massively and the remaining range is unpredicatable and tiny. Do you experience the same?
(never mind the total range - I accidently left home with only 67%)

2) check these stats: according to these I only got 754Wh out of my 1110Wh battery. Is this a normal figure? 

[Tawpie]

4 hours ago, reach said:

I accidently left home with only 67%

If this is true

4 hours ago, reach said:

I only got 754Wh out of my 1110Wh battery

Then this makes sense (67% of 1110 is 737)

 

This points out how difficult (or impossible) it is to equate a reported state of charge to remaining range. It is not linear, which is why EUCWorld has that special algorithm developed based on a lot of data. In spite of a great deal of effort, the special algorithm isn't accurate enough for me to rely on.

One thing about Li Ion batteries—when they're nearly depleted, they go down very very quickly. This characteristic is what you've documented.

Perhaps it'd be better to monitor the battery voltage and know at 64V is basically: you'll be walking very soon. You can set EUCWorld to use custom 'full' and 'empty' settings based on battery voltage, that's what I do!

Edited June 19, 2022 by Tawpie

[reach]

7 hours ago, Tawpie said:

Then this makes sense (67% of 1110 is 737)

No, the 754Wh were from a trip where I started at 100% (actually 97% according to the stats)! So I really only got 754 out of 1110.

I found an older V11 ride: there I consumed 972Wh AND finished with 60% battery left(!!!!)
 

 

7 hours ago, Tawpie said:

One thing about Li Ion batteries—when they're nearly depleted, they go down very very quickly. This characteristic is what you've documented.

Hmm, yes, but my V8 reaches the fully specified 30km and the V11 reaches at least 100km. They give me 100% of the capacity. I rode both until the very end and, while I might have gone slower towards the end just as a safety measure, the wheels behaved normally. The S18 becomes useless after 70%. From there it feels like a "limp home" mode. That's quite a massive difference.

 

7 hours ago, Tawpie said:

Perhaps it'd be better to monitor the battery voltage and know at 64V is basically: you'll be walking very soon. You can set EUCWorld to use custom 'full' and 'empty' settings based on battery voltage, that's what I do!

that's interesting, thanks. Will check it out.

 

 

[yoos]

2 hours ago, reach said:

So I really only got 754 out of 1110.

The problem is you never had 1110Wh to begin with. EUC manufacturers simply multiply the "rated" energy capacity of a cell by the number of cells. You might get this "rated" energy out of your cells only if you let them down to around 2.75 (or whatever the cells are allowed to go down to by the spec sheet). For safety reasons EUCs don't let it sink that far down. Moreover, to get the full energy you have to leak it out at very low currents, otherwise much will be lost to heat. 

Another problem is that battery % is reported linearly in voltage, i.e. battery state = (V-V_min)/(V_max-V_min). However, energy stored is not linear in voltage. Therefore, at lower voltages you get less energy per increment in voltage. In other words, the lower "30%" of your battery hold much less range than the top "30%".

I will illustrate with a graph for LG 18650 MJ1 cells (which are used in KS16S, KS18L, KS18XL). The nominal capacity is 3500mah. Multiplying by nominal voltage 3.7V we get 12.95Wh. A KS18L holds 80 such cells for a total of 12.95Wh*80=1036Wh. This is indeed what Kingsong advertises. However, from experience I feel that I have closer to 800 Wh available in my wheel. 

Indeed, here is an energy-voltage graph pulled from here.

This illustrates how much energy is harvested at each voltage for different set currents. You see that at best they got 12Wh from the cell, when draining at a low current of 0.2A. Next, they drain down to 2.8V, while the Kingsong EUC will shut down at 3.0V (iirc). That's  around 11.7V. Finally, in real life you draw higher currents. In my typical commute (41kph max speed, 28.3kph average riding speed) my typical cruising current is 10A. That's in a 4p20s battery so we have 2.5A per cell.  That's between the yellow and blue curves on the plot, so I can only hope for around 10.8Wh per cell in calm commute mode. Multiplying by the 80 cells I have I get ~860Wh in total instead of the advertised 1036Wh! 

Now to illustrate non-linearity: My typical commute is roughly 160Wh of energy consumed and around 8.5km travelled. To compare with the plot I'll divide by 80 and get 2Wh per cell. I'll take the lightblue curve (2A per cell or 8A total on the 4p battery) and find

start: 

4.20V, 100% battery, 0Wh consumed, 0km travelled
3.93, 77.5% battery, 160Wh, 8.5km
3.76, 63% battery, 320Wh, 17km
3.60, 50% battery, 480Wh, 25.5km
3.45, 37.5% battery, 640Wh, 34km
3.30, 25% battery, 800Wh, 42.5km
3.00, 0% battery, 880Wh, 47km

See how I made 5 trips and had "25% left" reported by the EUC? Should be enough for another trip but in fact only gives me half a trip with voltage dropping very fast.

Edited June 20, 2022 by yoos

[The Brahan Seer]

2 hours ago, reach said:

The S18 becomes useless after 70%. From there it feels like a "limp home" mode.

I am surprised you are feeling such a big difference then. In my experience the power is certainly best from 100%-70%. As stated above the first few percent used has a great impact on range.  I leave at full charge on a longer ride ie at 100% not 97 or less. 70%-30% seems to be the next level down but you can still travel relatively quickly. After 30% is as you say pretty much useless if you want to go quicker. 

My stats are 75Kg rider with gear. Max speed 27Mph, mostly between 15-27 if on street with some hills/ bit of wind. I get around 30 miles till 30% going at these speeds. 

If I go much slower say 5-27Mph, mixture of tricks, trail, pavement, road etc get around 40 miles.

 

 

[reach]

4 hours ago, The Brahan Seer said:

I am surprised you are feeling such a big difference then. In my experience the power is certainly best from 100%-70%.

Sorry, I think this was mis-leading: I didn't mean it's useless with 70% capacity, but AFTER 70%, =with 30% capacity. 

I'm not a native speaker, so maybe that was poorly worded.

Your range figures are compareable to mine indeed. I'm heavier and I'm usually going Vmax (never managed to go slow on the S18 - it's just such a great wheel to drive :-)) Can you also confirm the drainage towards the end? Not only the throtteling, but also that the last 30% only last 4-5km?

 

4 hours ago, yoos said:

The problem is you never had 1110Wh to begin with.

That's why I asked the question.
I studied electronics (a long time ago), so I know the basics. However, real life interestingly tells a different story: electric vehicles (I have one) pretty much give you what the battery capacity is telling. There is some throtteling, but minimal compared to the S18. Also, as said, my Inmotion wheels behave very different. They reach their specified range AND they don't throttle. The S18 reaches HALF its specified range(!) and throttles like crazy.
Also, as said, the V11 gets many many more Whrs according to the very same app (EUCworld)

I think the key here is the battery management. It knows, or at least it should know, the battery's characteristics and report figures accordingly =non linear.
Either KingSong is doing a terrible job here, or my battery is broken. Still not sure what's the case. 

[yoos]

41 minutes ago, reach said:

The S18 reaches HALF its specified range(!) and throttles like crazy.

The S18 has only 3 parallels which is not enough when using high-capacity cells (the V11 and 18L have 4p). The cells are forced to operate at higher currents which leads to less efficiency (more energy lost to ohmic heat dissipation). Moreover, there is voltage sag (which I didn't even mention above): if you are drawing current the battery will exhibit lower voltage. This is seen on the plot: this very quick drop in voltage once the experiment commences. The drop is proportional to the current, as it should.

7 hours ago, reach said:

972Wh AND finished with 60% battery left(!!!!)

Your V11 (and/or EUC World) is misleading you. No way can you squeeze more than 1500 Wh out of the V11. Possible explanation: EUC World only calculates how much energy you consume when consuming but does not subtract regenerated energy. Example: you go uphill and spend 1000Wh, then you go down the hill and regenerate 600Wh. EUC World reports "1000Wh consumed" while the actual net balance is -400Wh). This should be easy to check integrating VdI for a given tour, or better yet we just ask @Seba  Does "consumed energy" in EUC World account for energy restored when braking? 

Edited June 20, 2022 by yoos
grammar

[Funky]

Same for my 18xl at 100% charge - i can do 20km ride and my battery will drop down to ~90%.

If i do the same ride from 50% - it will drop down to 25% after those 20km.

More empty battery - it will drop faster. (Doh i didn't notice any speed drop at 25% battery. Still was going ~35kph speed.)

Also most people don't like to ride under ~40% battery. As wheel loses power, it loses performance. Sure you could keep going till 0% battery. I personally count really only first 60% as the "real" battery. Last 40% are simply there for "safety".   Same as car - you don't ride till you have empty gas can.

 

 

Little bit off-topic. Does someone knows how many cells are in ks18xl? 120? And how many are connected in row in battery pack? (How many batteries connected in row.) If wheel has 120 cells - 2 packs, each 60. That's 20x3 so it's 3x1 in row?

Edited June 20, 2022 by Funky

[Ksmack]

The Molicel batteries are only available through eWheels in the US right now. I don’t use EUC World (iPhone user here), and I don’t think DarknessBot tries to estimate the Wh consumed so I can’t compare. I was told by eWheels that the Molicel packs are more efficient (less losses due to dissipation) compared to the standard packs, so even though their capacity is smaller, the loss in range isn’t that big. 
 

I definitely get sped throttled when under 30%. I feel like I get dropped to about 20mph down to about 10% let. Then things fall off a cliff. With a few percent left I’m down to walking speed. This has actually helped me out in the past. I’ve been to far from home if I’d been riding to speed. Instead, the throttling helped me make it back. The wheel nearly died coming up my driveway. The real solution would of course be to have a bigger battery!

I did a much slower ride recently (15-23mph) and I estimate I could have gone about 38miles to empty. 

Edited June 20, 2022 by Ksmack

[reach]

57 minutes ago, yoos said:

Your V11 (and/or EUC World) is misleading you. No way can you squeeze more than 1500 Wh out of the V11. Possible explanation: EUC World only calculates how much energy you consume when consuming but does not subtract regenerated energy. Example: you go uphill and spend 1000Wh, then you go down the hill and regenerate 600Wh. EUC World reports "1000Wh consumed" while the actual net balance is -400Wh). This should be easy to check integrating VdI for a given tour, or better yet we just ask @Seba  Does "consumed energy" in EUC World account for energy restored when braking? 

Damn, you're right!
The referenced ride was on a mountain from 1050 to 1850m hight and back. So there was a lot of recuperation.
I found an older ride with the V11 which was mostly flat - and this proofs me wrong. Even when I said that the V11 reaches the 100k easily. See the screenshot. 

Comparing these 2 rides the S18 doesn't look so bad. 

In my defense: I wasn't lying when I said that the V11 reaches the 100km. I used to go the same 40km route every day for training and I only charged it after 2 days and then the battery was still not in the yellow area (Inmotion features a battery indicator, thankfully!) But looking at the app it might have been more drained than the inducator suggests. Still, it didn't throttle at any time. It must have reached that distance because I was riding slower back then. It took me a while to get used to 18", coming from a 16".

[The Brahan Seer]

6 hours ago, reach said:

Can you also confirm the drainage towards the end? Not only the throtteling, but also that the last 30% only last 4-5km?

Kingsong  recommend not going over 16 Mph (26Kph) @30% battery or less, so I have never gone faster than that at these battery levels.

I do not go below 35% before recharging very often. Actually looking at previous diaries I have done so 4 times since I got the wheel 37% to 5% =9 miles (14.5Kms), 43% to 2%= 9.3 miles (15Kms), 42% to 6%=9.4 miles (15.1Kms), and 50% to 9%=10.2 miles (16.4Kms). These would be travelling at 16MPH or less except for the last entry.

[ijeff]

21 hours ago, The Brahan Seer said:

Kingsong  recommend not going over 16 Mph (26Kph) @30% battery or less, so I have never gone faster than that at these battery levels.

I do not go below 35% before recharging very often. Actually looking at previous diaries I have done so 4 times since I got the wheel 37% to 5% =9 miles (14.5Kms), 43% to 2%= 9.3 miles (15Kms), 42% to 6%=9.4 miles (15.1Kms), and 50% to 9%=10.2 miles (16.4Kms). These would be travelling at 16MPH or less except for the last entry.

Do you have a source for the recommendation? I wonder what their recommendation might be with the Molicel packs.

[The Brahan Seer]

4 hours ago, ijeff said:

Do you have a source for the recommendation? I wonder what their recommendation might be with the Molicel packs.

Yes I got it from @Kuji Rolls Kingsong S18 Review. Details it in the description. [He was involved in the development of the S18] This is the link...

 

[Seba]

On 6/20/2022 at 4:57 PM, yoos said:

Possible explanation: EUC World only calculates how much energy you consume when consuming but does not subtract regenerated energy.

EUC World accounts for both current directions, so the result is energy consumed minus energy regenerated. Reliability of this calculation mostly depends on wheel circuitry and measurement precision, so it's best to take this value with a grain of salt. Anyway, for most of Inmotion and King Song wheels, this value (along with average energy consumption) tends to be calculated suprisingly reliably. I use it for range estimation when I'm out for a long-distance ride on my 18XL and have never yet been disappointed with it.