Setting bellow 90% charging ratio? (s22)

[RoboFixIt]

Hi please see attached screenshot of the KS charging ratio option. I have been looking into this for a few weeks now, asking experienced professionals and learning more about batteries to try and get a clear answer but it's like there's some kind of debate about this... I tried searching the forums but it seems the search feature is not working very well, I hope that could be adjusted someday? I know there's been past discussions on this because of some of the sources I found on this topic are referring to electricunicycle.org.

There's definitely something not right about the BMS in the s22 or maybe the software because no one is getting nearly the kind of range that's been advertised (200km+). The range feels like it's almost the same as the 16x and that's just disappointing. I bet with the right set up we could possibly get at least twice the range out of the s22. I wonder if anyone has tried to overcharge the s22 for a few hours?

I tried digging a bit deeper into the battery's used in the s22 (LG M50LT 21700 5000mAh 14.4A) and I found some sources recommend not to charge above 80%...? 
How are we supposed to get anywhere with that? With an 80% charge you may get you about 70km of range if your lucky. Sometimes you just want to go out, run a few errands, grab lunch, ride with some friends and not have to worry about charging within the first hour.... So you kind of need to charge to 100% or you could risk having to call a cab because your batteries are out of juice.

At this point I am not charging my iPhone to 80%, I'm not charging my MacBook to 80% or GoPro etc.... So why should I charge an EUC to 80%? I'm wondering if anyone could shed more light onto this at all or even post links to past discussions regarding charging ratios in the forums. Thank you!

 

[Tawpie]

There's more than a bit of discussion about charging... but here's the tl;dr. Highly recommended, must watch IMO

https://youtu.be/pgr7-b3eBm0

[plentora]

Always charge to 100% because there isn't any practical reducement of battery capacity happening. (*)

The other reason is that 99% of the wheels are using passive balacing meaning they balance ONLY when charged to full. Not at 80%, not at 90%. Full. If you don't charge to full, your battery will become ticking time bomb as it gets very unbalanced.

 

[Chriull]

17 hours ago, ElectronxCycles said:

At this point I am not charging my iPhone to 80%, I'm not charging my MacBook to 80% or GoPro etc.... So why should I charge an EUC to 80%? I'm wondering if anyone could shed more light onto this at all or even post links to past discussions regarding charging ratios in the forums. Thank you!

As the others stated this potentially leads to much more problems as one could gain.

This tip is irresponsible and one could claim kingsong wants to push their battery business ;(

However - if one knows what one is doing (mainly periodically checking the reported single cell group voltages before and after balancing) this feature can be a support to increase battery life. So many generations could enjoy this batteries

If one is not sure or just want to enjoy his wheel the only sensible and responsible advices are:

Fully charge the wheel (until charger changes to green light)

Keep it somewhere very, very roughly around 50-70% for storing.

Be sure ones wheel does not noticable drain the battery during storage!

Don't store the batteries at high temperatures (in a shed in the summer head...)

So for storing this feature could be used - after the "last" ride just charge it to ~70%.

Or for "optimizer" (having fun to fiddle around) - after a ride one charges to some 9x% and half hour to hour until the charger light turns green is charged before each ride.

 

[alcatraz]

That's a good feature. I'd use it for when I don't need max range which is most of the time. I wouldn't hesitate to pull that to 100% when needed. I'd just pay attention to the cell group voltages which the S22 displays. You want to stay under 4.25v.

[mrelwood]

 

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

no one is getting nearly the kind of range that's been advertised (200km+).

The small print is not easy to find, but EUC manuals generally have the announced range measured with a 60kg rider riding at a steady 20km/h pace at 25•C without wind. If you recreate the test you should get pretty close…

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

The range feels like it's almost the same as the 16x and that's just disappointing.

1554Wh on a max 45-50km/h wheel vs 2220Wh on a max 70km/h wheel. Makes sense. Ride the S22 like you’d ride a 16X and the ranges should be in the same ballpark, minus the added weight of the S22.

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

I bet with the right set up we could possibly get at least twice the range out of the s22.

That wouldn’t make much sense. It’s a 2220Wh wheel, and it can only get a range that resembles it’s capacity, the combined weight of the rider and the wheel, riding style, and other environmental factors.

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

I wonder if anyone has tried to overcharge the s22 for a few hours?

If the balancing feature works as it does on almost all other wheels, it should just keep balancing the cells, slower and slower. Although, I’ve heard about a lot of inconsistencies in the displayed voltage between the S22’s BMS, mainboard, charger, and a multimeter. So the system might not be optimized at all to actually even balance the cells.

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

I found some sources recommend not to charge above 80%...?

When you have an active cell balancing system like they have in e-cars, this is the way to achieve around 1000 charge cycles instead of the regular 300. But on EUCs the charge cycles are significantly less. On the S22 300 full Li-ion charge cycles would mean something like 30’000km before your capacity reaches 80% of its original. So there’s rarely need to try to extend it any further. Other things matter so much more.

On 10/30/2022 at 7:14 PM, ElectronxCycles said:

So why should I charge an EUC to 80%?

You absolutely should not! I agree wholeheartedly with the creepy guy in the video @Tawpie linked to! (Thanks @Tawpie!)

 So yeah, like @Chriull said, unless the balancing feature on the S22 works differently than we’ve been able to see, the misleading description of the feature is an irresponsible move from KS. In which case I would be hell bent in making them change the text, if they were like Inmotion and actually listened.

[Tawpie]

It turns out that there are a lot of settings for the S22 BMS that mere mortals don't have access to, and some of those settings hint that the balancing algorithm has a number of different settings the factory can invoke. I'm not sure if "balance at this voltage" is in there, but if it is indeed a setting, and if it actually works (that's a huge, giant if), then it might be possible to short-charge and still have the pack balanced. If and If and IF then maybe the statement wouldn't be inaccurate.

Verification one way or the other would be helpful. But when you short-charge you give up range-on-today's-ride for (maybe) more range at 30,000 km.

Edited November 1, 2022 by Tawpie

[mrelwood]

If it indeed did balance at a lower voltage, that would be über cool! But I have a really hard time to believe they would successfully do that, already based on the reports on conflicting voltage readings.

[RagingGrandpa]

On 11/1/2022 at 11:15 AM, mrelwood said:

balance at a lower voltage

That's difficult, because this "S22 charging ratio" is managed by the controller and does not affect the charger. So the charger will continue full-current charging, right until the moment the controller disconnects it. 

Voltage-balancing in the presence of a (5A?) charging current is a bad idea, because of the natural variation in cell resistance.

A valid approach would be "balancing during rest" - after the charging has been stopped and no current is flowing. But this has its own problems, requiring some time-out logic to prevent it from draining the pack to 0% during storage, and reducing final state-of-charge (bleeding energy without a charger connected to supply it). 

A test would be lovely, and could be as simple as:

1. Measure imbalance: after resting the EUC for an hour, inspect cell voltages with the S22 app and record the voltage difference between the lowest and highest cell.
2. Go for a ride.
3. Before the next ride, recharge using the 90% setting.
4. Go for a ride.
5. Recharge to 90%.
6. Repeat for 3 more rides.
7. Measure imbalance: after resting the EUC for an hour, inspect cell voltages with the S22 app and record the voltage difference between the lowest and highest cell.

After a week of this, we suspect the "imbalance" in step 7 to be notably larger than step 1. 
(If that's the case, cell balancing isn't working, so quit using 90%!)

[mrelwood]

46 minutes ago, RagingGrandpa said:

That's difficult, because this "S22 charging ratio" is managed by the controller and does not affect the charger. So the charger will continue full-current charging, right until the moment the controller disconnects it. 

Ah, good point! Seems very improbable that the feature would do anything else but to abruptly cut off the charge at the given charge level.

 Wasn’t KS mainly a BMS manufacturer before EUCs?? How can they fail this bad??

[alcatraz]

The S22 has a smart bms and can display individual voltages. Why can't the S22 owners just take a screenshot before hitting the charge stop and compare with a while after? Then we'd know if it balances or not.

Setting it higher, like 90-95% should be better than lower, for testing purposes. This because the individual voltages deviate more at the extreme charge levels. It's easier to hit the balancing trigger with a greater delta.