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25% range loss after just 1170 kilometers ?


HermanTheGerman
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Hi mates, I have a question, but first the facts.

In August this year I did a rangetest with my KS16 (680 Wh, fully loaded, charger shows green LED):

I could drive 42 real kilometers until battery was nearly completely empty, which I think is fine (80 kg rider, flat asphalt terrain, average speed around 20 km/h).

Now, as you can see below, I did the same test again, and results are quite different: 32 km only!! (Shown on the left screenshot. Height difference shown is wrong, it is only 60m)

The only differences between these 2 measurements are the temperature (in August it was around 33 centigrade for the battery, and now 23 (see right screenshot)), and also the age of the battery (in August  it was driven between 200 and 300 km, and now (middle screenshot) 1458/1,25 ~> 1170 real km).

What do you think, where does this massive range loss (25% !) come from ?

Can it be the temperature difference (10 degrees), or is it really possible that the battery became so much weaker after just 1170 kilometers ?

Any thoughts welcome.

Cheers, htg

PS: Don't misinterpret the right screenshot, you can drive at maximum 1-2 kilometers with that, and I also had this remaining charge in August.

 

RangeLoss.jpg

Edited by HermanTheGerman
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@HermanTheGerman from what I read on this forum, it could be one or more of the battery cells have gone bad, does the battery still show the same voltage at full charge as before?  Also is the tire pressure the same as before, what pressure do you ride on?

I think it is more likely that the charger might be going bad and not loading the batteries as much.  Maybe you could check the charger output voltage against the specifications on the charger, and if it is lower, adjust the potentiometer to the proper voltage, just guessing here.

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If you are riding 40 per charge, the difference in range (800 km) equates to approximately 20 battery cycles. It is too early for the battery to lose 25% of its performance ( even if you charged it full and discharged to zero) . If you had done about 100 cycles id say its quite possible to lose 20-25%. 

By the way, did you discharge the battery to the very end, or do you normally plug it in when it still has juice?

also, are you confident that the mikeage in the app is correct? Did the app aleays track you when you were riding? How many battery cycles do you think you had?

in any case i recommend you repeat the test. Some range test resukts are quite different from others. A lot of things can come into play, - riding surface, wind, additional weight you are carrying, frequency if accelerations and braking, etc

Edited by Cloud
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Hy, 

your 42 km...you measure them on the KS app only???

Then it is easy...there was about a 20% fault on the range measurement of the KS app in ealier version....

So that would be why it was so much in August...

it is way to early to get such a batterie sag!

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11 hours ago, steve454 said:

@HermanTheGerman from what I read on this forum, it could be one or more of the battery cells have gone bad, does the battery still show the same voltage at full charge as before?  Also is the tire pressure the same as before, what pressure do you ride on?

I think it is more likely that the charger might be going bad and not loading the batteries as much.  Maybe you could check the charger output voltage against the specifications on the charger, and if it is lower, adjust the potentiometer to the proper voltage, just guessing here.

I check the tire pressure before every ride, it is always quite a bit above 3 bar. I prefer a hard tire for several reasons.

Battery per se looks good, I don't think one cell is bad, that would be expressed in more asynchronous behaviour from charge point of view (full to empty).

 

8 hours ago, Cloud said:

If you are riding 40 per charge, the difference in range (800 km) equates to approximately 20 battery cycles. It is too early for the battery to lose 25% of its performance ( even if you charged it full and discharged to zero) . If you had done about 100 cycles id say its quite possible to lose 20-25%. 

By the way, did you discharge the battery to the very end, or do you normally plug it in when it still has juice?

also, are you confident that the mikeage in the app is correct? Did the app aleays track you when you were riding? How many battery cycles do you think you had?

in any case i recommend you repeat the test. Some range test resukts are quite different from others. A lot of things can come into play, - riding surface, wind, additional weight you are carrying, frequency if accelerations and braking, etc

Hmm, I would estimate around 20 per charge, then that would be 40 charging cycles. I try to keep the battery mostly between 20 and 90 percent, I only charge it fully when I intend to do a long ride (30 km+). Maybe it is often above 80%, but rarely above 90%, and very seldom below 20% (the latter only if I do a test or when I changed plans while riding. I would say that it was at maximum 5 times below 15%, and never completely empty).

The mileage on runtastic app is correct, I confirmed that several times with a Garmin 64s, where the differences were only +/- 1%.  Thats also the reason why I know that I need to divide the mileage on the Kingsong app by 1.25 to get the real distance, this factor is quite accurate for all distance values on the KS app (at least for the KS16).

I would say since I own the wheel I had 60 to 80 charging cycles, but as mentioned most of them between 20 and 80%.

You may be especially right with your last remark: Although there was no wind at both tests, maybe I drove faster at the last one, and for sure I was a few kilos heavier.

 

3 hours ago, KingSong69 said:

Hy, 

your 42 km...you measure them on the KS app only???

Then it is easy...there was about a 20% fault on the range measurement of the KS app in ealier version....

So that would be why it was so much in August...

it is way to early to get such a batterie sag!

No, I believe the 42 km were measured on a Garmin 64s - but now, because you said that, I'm not completely sure anymore. Maybe that were still the times were I trusted the distances on the KS app. I will check that, thats a good point.

----- edit ----: Checked it meanwhile, no the distance in August was also measured with the Garmin, not with the app, so it should be accurate. ---- edit ----

BTW, the riding distances on the app and wheellog are still wrong, they are reported that way from the wheel. At least for my KS16 I need to divide the app values by 1.25 to get the real distances.

 

 

 

 

Edited by HermanTheGerman
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5 hours ago, HermanTheGerman said:

Hmm, meanwhile I discovered, that at the August test my average speed was a little bit above 16 km/h, and now it was 20,8 km/h.

Maybe that explains the range difference.

I'll repeat the test next week setting a beep at 22 km/h, so keeping the maxspeed artificially down.

Let's see what the distance will be then.

Speed will have a very significant effect on range and so will temperature. Higher temperatures improves the chemical reaction but does impact the lifespan of the cells, however as @Cloud has said it probably isn't that the range has dramatically reduced yet.

However the problem with individual cells, especially when there are a large number of them, is that it is a bit like the half life of an isotope. On average the cells will last so long but one cell could fail at anytime. So it is alsways possible a cell or two might have started to fail and With 4 cells in parallel A few poor cells may drop the range by 25%. Definitely worth doing like for like tests to see what is really happening.

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You should do the two tests with the same speed, and you should also keep the speed constant throughout each test (or alternatively have the same speed profile in the two tests). Wind resistance is proportional to the square of your speed. There are lots of unknowns here (your wind drag coefficient, rolling friction, internal losses in the wheel), so how much your range will be reduced due to higher speed is not known, but it might account for a large part of your observed range reduction, if not all of it.

:D

Have fun!

 

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Hi All,

thanks for the ideas and recommendations.

After todays test I saw that it's really mainly dependent on average speed and head wind. I attached both tests below for easier comparison.

However, today it was that cold that I couldn't stand more than the 27 km mentioned. It can be seen that the battery is still 38% full, which means I could still drive for approximately 11 to 14 km (from my experience). So even if I add the worst case (11km) to the already driven 27, that would mean 38 km range, which is fine for me for today.

Though I set Alarm1 to 21 and Alarm2 to 22 km/h, I only could manage the average speed going down to 19.2 km/h  (because it was so cold, I wanted to go back home fast :) ) from the former 20.8, but not to the 16 from my first test in August.

But these 1.6 km/h difference were enough to get a longer range today, though there were stronger winds today than last time (but because I drove the same way back, headwind and tailwind should approximately even each other out).

RangeLoss.jpg

RangeLoss2.jpg

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  • 2 weeks later...

I didnt read all here but how was the outside air temperature ?

I wonder if all the battery packs have an BMS because I also noticed that even after charging the whole night and chargers green indication the app shows not 100% full more like 96%.

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On 7.12.2016 at 11:50 PM, Adlers83 said:

I didnt read all here but how was the outside air temperature ?

Around 5 centigrade at the first and around -2 centigrade at the second attempt. But battery temperature was always above 20 centigrade.

On 7.12.2016 at 11:50 PM, Adlers83 said:

I wonder if all the battery packs have an BMS because I also noticed that even after charging the whole night and chargers green indication the app shows not 100% full more like 96%.

At my KS16, if I really keep it on the charger until it is green, then also the app shows 100%.

Edited by HermanTheGerman
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  • 8 months later...

Old thread, but I haven't seen this mentioned and this is a relevant thread.

I have noticed that I can extend the range of my wheels significantly by taking the time to crawl the battery to as empty as possible, waiting for a few hours, then charging to full including balancing. Best to leave in charger for 9 hours or more.

My Lhotzs' usable range increased from 14 to 17, that's 20%!

I don't know the tech so I don't know if the increase happens on the battery side or just BMS calibrating itself.

I would also like to remind that 100% is not 100%. Meaning, if you stop the charge as soon as the device shows 100% battery, it is not yet full. The cell balancing charge has about just begun, and will take a long time to complete. All this time the device shows 100% and the charger light is green.

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4 hours ago, mrelwood said:

Old thread, but I haven't seen this mentioned and this is a relevant thread.

I have noticed that I can extend the range of my wheels significantly by taking the time to crawl the battery to as empty as possible, waiting for a few hours, then charging to full including balancing. Best to leave in charger for 9 hours or more.

My Lhotzs' usable range increased from 14 to 17, that's 20%!

I don't know the tech so I don't know if the increase happens on the battery side or just BMS calibrating itself.

would also likIe to remind that 100% is not 100%. Meaning, if you stop the charge as soon as the device shows 100% battery, it is not yet full. The cell balancing charge has about just begun, and will take a long time to complete. All this time the device shows 100% and the charger light is green.

I've noticed that if I leave the Ninebot on green for an extra hour or two, it will still show 100% even after 2 miles of riding.  But sometimes I take it off charge while it is still red, and the app shows 100% , even thought it was only close to being fully charged.  And then after 2 miles of riding it will show something less than 100%.  But it seems to me also to be good to leave on charger for extra time.  I think you are right about leaving it on the charger longer to get more range.  

I only went below 20% battery one time, just to see what would happen, and got the speed restriction.  I never went down as empty as possible, I might try that one time to see what happens.  

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It has been advised that the wheel should be left to the charger for extended time every 10 charges or so. This will complete the balancing of individual cells. Other than that it is beneficiary to battery life to stop the charging at 80-90%.

I'm all for extending charge cycles and all, but I don't think many of us are willing to take the hit on the max distance. Cost of a bigger battery vs reaching the end of battery life sooner... I already have the largest battery available for this model.

I wouldn't deflate the battery to 0% every time, not even every 10 charges. But perhaps every 50 charges.

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On 24/11/2016 at 11:25 PM, HermanTheGerman said:

Hi mates, I have a question, but first the facts.

In August this year I did a rangetest with my KS16 (680 Wh, fully loaded, charger shows green LED):

I could drive 42 real kilometers until battery was nearly completely empty, which I think is fine (80 kg rider, flat asphalt terrain, average speed around 20 km/h).

Don't the KS16's have more range than that? Or only the K16S? This is the same range as my Inmotion V8.

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Realistic ranges are taking away 12wh/km(slow driving) to 16-18wh/km (fast)on a batter y.

There the Ks16 is about the same as a V8...so nope, even if the V8 might be a bit more effektive, realistic is that with the same person and same speed you only have about 3/5 of range on an V8...

Unfortunatly the range is mostly announced with about 10wh/km...here 50km for v8 and 80kmh for ks16 from the producers....but these numbers are totally unrealistic, they dont take into account the real consumption and also not that you have to leave at least 10-20% in the batterie before stopping.

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10 minutes ago, KingSong69 said:

Unfortunatly the range is mostly announced with about 10wh/km...here 50km for v8 and 80kmh for ks16 from the producers....but these numbers are totally unrealistic, they dont take into account the real consumption and also not that you have to leave at least 10-20% in the batterie before stopping.

I get about 40km on my V8. But I am not a heavy rider :) 

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12 hours ago, Keith said:

I think you may be confusing two different events and making 2+2 = 5

...

Perceived and well documented wisdom is that it is a very bad idea to regularly cycle Lithium batteries all the way to empty and even doing it occasionally will still negatively impact battery pack life. I.e. It should be done ONLY when absolutely necessary and maximum range is needed.

...

  • Flattening the pack deliberately to improve range, is not only a bad idea due to ageing, but on wheels other than IPS you risk possibly taking some cells low enough to damage them, particularly if your battery is either not of the highest quality or is more than (say) 2 years old. 

This is very important info Keith, thank you. May I ask for clarification on:

"it is a very bad idea to regularly cycle Lithium batteries all the way to empty"

Do you mean device reported 0% (3.0-3.2V per cell on an EUC) or beyond that, to actually truly empty? 

What still puzzles me is that it was normal for me to leave the Lhotzes charging over night, so the cell balancing had surely happened before I did the zeroing. The Lhotz #2 was only a month old and my brother had kept it at 70-100% charge over his learning perioid. After I first charged it full over night, the range was very low. Zeroing the battery had a huge effect. The Lhotz #1 I had used for 1000km (2 months), leaving it over night for every other charge. Zeroing did a clear improvement in that also.

It is common to read "expert advice" on phone and laptop Li-ion batteries to do a 0-100% charge once a month or so to "recalibrate" the battery. That too has been clearly effective on some phones I've tried it on.

http://www.techadvisor.co.uk/how-to/mobile-phone/how-properly-charge-phone-battery-3619623/

Am I right in guessing that the guide above only recalibrates the controller and does nothing (good) to the battery cell itself? And that EUC batteries don't have a similiar controller that can be calibrated? If so, I really don't understand why the zeroing worked so well on my Lhotzes.

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7 hours ago, mrelwood said:

Am I right in guessing that the guide above only recalibrates the controller and does nothing (good) to the battery cell itself? And that EUC batteries don't have a similiar controller that can be calibrated? If so, I really don't understand why the zeroing worked so well on my Lhotzes.

You are asking important questions here as this is where you start to get into grey areas - not with batteries, but with electronics.

Firstly, as far as looking after batteries is concerned you probably cannot do better than this article: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries 

However, several articles have suggested electronics can "go out of calibration" and the above article does say: "The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery)".

This would require that the battery charge state display is a "Coulomb counter" and is showing remaining capacity by counting how much charge has already been consumed, As far as I can tell, most EUC's simply report voltage - easily spotted, if accelerating fast results in the EUC reporting a lower battery that, suddenly, is higher again when you stop - it is just voltage it is reading and it should not be possible for that to go out of calibration. If the charge goes down steadily then it might well need calibration occasionally. 

The other point you raise is also very valid 0% on the EUC is really NOT 0% if the display is a voltage reading, it might be if it is Coulomb counting. For example my early KingSong 14C decides that empty is 55 Volts = 3.43V / cell. This would be damn near empty as there is very, very little capacity between 3.4V and 3V (OFF-LOAD), unfortunately it does it under load with the result I always have at least 30% of unusable capacity. Later KS-14C's have this reset much lower (48 or 50V?) However there is usually a healthy 10-20% capacity left to protect the battery - particularly from some cells possibly being lower than others.

Im not sure which way of measuring the IPS uses, but if it does monitor every cell it can allow the battery to drop to nearer 0% as it will report empty on the lowest cell.

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Hi mates,

this is an old thread, I don't have a problem with that any more.

At the time I wrote that I  surfed against strong headwinds and 5 km/h faster on average than with a prior measurement, so it was clear that I had a shorter range.

I also want to mention that I have the 640 Wh variant of the KS16B, not the 820 Wh. I'm also mostly cruising over longer distances, with a high average speed, between 25 and 30 km/h, so I reach a range between 40 and 45 km on average, which is fine for me (the wheel has now more than 3000 km on it).

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17 hours ago, Slaughthammer said:

How fast do you ride on average? That's also a huge factor to take into account, but if you'd read the whole thread before posting, you'd already know that...

Speed limit set in the app to 25 km/h, I usually ride somewhere around 22 when going at constant speed according to the logs.

Makes sense that the range does not scale linearly with speed :) 

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KingSong keeps some % of battery capacity as a reserve, to avoid damaging the battery by draining it to 0%. The % depends on the model (it can be even 20%). However, you should never drain your battery anyway.

If the battery doesn't have a factory flaw, and you don't push your device to cut-offs, it should live long and fine.

Just remember to charge it at least once a month and do not leave for longer periods of time, especially in winter. When you need to store for longer periods of time, keep the charge at least above 50% and charge systematically. It is all required by the manufacturers to keep the battery warranty.

If you follow the rules, bare in mind there are many factors limiting battery performance, such as:

- Weather - lower temperatures can decrease the battery performance significantly. Right now, there are no battery temperature control systems in EUCs (I'm looking forward to it!),

- Weather again - strong winds can drain the battery much quicker,

- Cruising speed - use a mobile app that shows your power usage and you can easily find out what speed is the most range efficient. It's like with cars - the more dynamic the ride, the more fuel is being burned,

- Route - in the same weather you can do 40 km by choosing one route, and only 20 by choosing another one. Any inclinations, bumps, obstacles are draining the battery quicker,

- Weight - carrying heavy stuff in your backpack will also affect the range,

- Lights and music also affects the range, but not significantly. Besides you need lights :D 

When your battery is low, you can try to ride more smoothly, choose better paths and slow down when you ride downhill, to get as much energy as you can (simply brake to ride slower downhills). Obviously it all won't extend your battery for another 10 km, but it may give you 500-1000 more meters to get back home without pushing the device :D 

 

Enjoy your KS16!

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