Just bought a new bike with a 17amp Panasonic battery. Previous bike had a 15 amp battery which performed as I expected.

 

So far done 46 miles and only gone down one bar out of five (20%) I estimate say 30% down. That would mean something like 140 miles total range which can't be right? The meter is a King meter KM529LCD

 

Usage so far: mid power setting. Cruising speed mainly on flat roads (York) in fairly calm conditions. My weight is 88kg

 

I conclude that my battery is fantastic or the meter is misleading me?

 

Any thoughts?

Just bought a new bike with a 17amp Panasonic battery. Previous bike had a 15 amp battery which performed as I expected.

 

So far done 46 miles and only gone down one bar out of five (20%) I estimate say 30% down. That would mean something like 140 miles total range which can't be right? The meter is a King meter KM529LCD

 

Usage so far: mid power setting. Cruising speed mainly on flat roads (York) in fairly calm conditions. My weight is 88kg

 

I conclude that my battery is fantastic or the meter is misleading me?

 

Any thoughts?

You'll have a better idea of its range after you've done some more miles....

Just bought a new bike with a 17amp Panasonic battery. Previous bike had a 15 amp battery which performed as I expected.

 

So far done 46 miles and only gone down one bar out of five (20%) I estimate say 30% down. That would mean something like 140 miles total range which can't be right? The meter is a King meter KM529LCD

 

Usage so far: mid power setting. Cruising speed mainly on flat roads (York) in fairly calm conditions. My weight is 88kg

 

I conclude that my battery is fantastic or the meter is misleading me?

 

Any thoughts?

I personally like Panasonic cells in my battery, (just by luck) I have never had anything else, or seen anything better.

Also, when going from a smaller to a larger capacity battery, of course the larger one (naturally!) has more capacity, its a simple given, as you know, or you wouldnever have bought one!

Also, the SOC will "vary less" because of that, which makes the bike I feel, "nicer" to ride IMHO, no cutting out on hills with a nearly empty battery....

Maybe some SOC meters are a bit "fooled" by that (a design problem possibly!), and possibly indicate far more capacity than they should?

The only way to find out is to go out there and empty the battery!

Then let us know your results!

Enjoy the new Panasonic battery! :)

Andy

I personally like Panasonic cells in my battery, (just by luck) I have never had anything else, or seen anything better.

Also, when going from a smaller to a larger capacity battery, of course the larger one (naturally!) has more capacity, its a simple given, as you know, or you wouldnever have bought one!

Also, the SOC will "vary less" because of that, which makes the bike I feel, "nicer" to ride IMHO, no cutting out on hills with a nearly empty battery....

Maybe some SOC meters are a bit "fooled" by that (a design problem possibly!), and possibly indicate far more capacity than they should?

The only way to find out is to go out there and empty the battery!

Then let us know your results!

Enjoy the new Panasonic battery! :)

Andy

Sorry SOC ?

Sorry SOC ?

"State Of Charge", sorry, I should have mentioned it.....

Andy

You can't go by the meter on any electric bike, though some are better than others. On your bike, all it is is a voltmeter and it goes down with the battery voltage. The battery voltage always accelerated downwards as you use up the battery because you are using watt-hours of energy. When the battery is full, you have 42v and when it's empty, you have 31 v, so you only get 75% as many watt-hours per volt when its empty. Also, as lithium battery discharges, it follows a more or less flat ramp-down line until around 35V, then it accelerates downwards.

 

The end result is that your last two segments will disappear a lot quicker than the first two. the only way you can monitor your range is with a wattmeter, though when you've run your battery right down a couple of times, you'll get an idea of how your meter behaves to get a good idea of how far you can go.

You can't go by the meter on any electric bike, though some are better than others. On your bike, all it is is a voltmeter and it goes down with the battery voltage. The battery voltage always accelerated downwards as you use up the battery because you are using watt-hours of energy. When the battery is full, you have 42v and when it's empty, you have 31 v, so you only get 75% as many watt-hours per volt when its empty. Also, as lithium battery discharges, it follows a more or less flat ramp-down line until around 35V, then it accelerates downwards.

 

The end result is that your last two segments will disappear a lot quicker than the first two. the only way you can monitor your range is with a wattmeter, though when you've run your battery right down a couple of times, you'll get an idea of how your meter behaves to get a good idea of how far you can go.

I suspect that the Bosch system is a little more sophisticated than a simple voltmeter. They are monitoring the current, so measuring the charge consumption with a microcontroller is easy. I know that your comments refer to a different brand, ..but ,just putting in a word for the higher priced system

Does anybody know what the voltages are for the various battery charge steps on the KM529LCD?

 

That, together with the results vfr400 posted before (https://www.pedelecs.co.uk/forum/threads/is-the-extra-5-amps-chewing-up-my-range.35664/#post-520066) should really help interpret the meaning of the battery meter.

 

I agree the Bosch is more sophisticated and feels more reliable. (Shame it can't give more sensible readings for range remaining as well, by basing it on a longer history). We have Bosch on our solo and KM529 on our tandem.

"State Of Charge", sorry, I should have mentioned it.....

Andy

I looked around on the IoT for you, and I am hoping this may help your understanding, as it appears to be fairly accurate:-

https://siliconlightworks.com/li-ion-voltage

It is important to note that all Li-ion cells, including the Li-ion cells contained in our Mobile Power Centers, are sensitive to voltage. A Prolonged low voltage condition within a Li-ion cell may cause the dissolution of metals (principally copper). Copper dissolves into the electrolyte solution at open circuit voltages below ~0.7 volts. This dissolved copper is re-plated within the cell upon subsequent charging and can cause undesirable effects and almost certainly will compromise cell performance (e.g. low capacity, poor cycle life, high self-discharge).

 

 

 

Similarly, high voltage can also cause the degradation of Li-ion cells, especially at elevated temperature. When a Li-ion battery is plugged into a charger, charging continues along a prescribed path until a state of charge ("SOC") of 100% is sensed by the circuitry. The charging is then terminated and the battery is allowed to very slowly discharge. It is detrimental to the cells to be kept at 98-100% SOC for prolonged periods of time (i.e. more than 10 days). This is why many cells are allowed to discharge to around 95% SOC or less before charging is re-initiated, even while connected to a charger.

 

The nature of Li-ion cells is such that the relationship between state of charge ("SOC") and voltage is fairly flat throughout much of the cell’s discharge range. A typical discharge voltage curve is shown below:-

The rapid fall of voltage at the end of the discharge cycle provides a relatively accurate means of determining when energy will run out. However, this also means that the SOC drops much more rapidly and can lead to an over-discharged condition if the cell or battery is left to sit for prolonged periods at a low SOC. This is due to the fact that Li-ion cells have an inherent self-discharge rate independent of any circuit load. This self-discharge rate is quite low at room temperatures around 20-25°C or less. Values of around 2% per month are typical. However, this rate can more than double when cells are exposed to high temperatures. Furthermore, ambient temperature can have a profound effect on the discharge voltage curve and must be considered during transportation and storage when the cells may be exposed to extreme high or low temperatures.

Well designed electronics will keep the cell(s) at somewhere between 4.2 and just under 3 volts. This is the safe "working area" for a Li-ion cell.

You can see that the battery discharges faster as it gets to the end of the charge. Just what you are noticing.

Multiply these single cell voltages by the number of cells in series in your battery.

For example, a 36 volt (nominal) battery, will have 10 blocks of series connected cells (number of cells in a block, connected in parallel is variable due to capacity and current design requirements!).

Never leave a discharged battery to its own devices for months, as the safety electronics can and will prevent further charging, and only a "Zer0 Volt Charger" MIGHT recover it, but damage will have been done.

Any questions, just ask please.

Andy

That graph is even flatter along the main segment than the ones vfr400 posted before. It really shows why a voltage based charge meter is so inadequate.

Just bought a new bike with a 17amp Panasonic battery. Previous bike had a 15 amp battery which performed as I expected.

 

So far done 46 miles and only gone down one bar out of five (20%) I estimate say 30% down. That would mean something like 140 miles total range which can't be right? The meter is a King meter KM529LCD

 

Usage so far: mid power setting. Cruising speed mainly on flat roads (York) in fairly calm conditions. My weight is 88kg

 

I conclude that my battery is fantastic or the meter is misleading me?

 

Any thoughts?

The battery is good and the new bike is economical on battery but you need to check the battery's voltage with a multitester to be sure.

The battery capacity is 17.5AH * 36V = 630WH

When the battery is full, it should show 41.5V, totally flat: 31.5V. Each Volt corresponds to 10% of the charge.

After 46 miles, the battery should show about 35V or 35% remaining.

I looked around on the IoT for you, and I am hoping this may help your understanding, as it appears to be fairly accurate:-

https://siliconlightworks.com/li-ion-voltage

that graph is not relevant.

John's battery is made with top grade Panasonic 18650B (3500mAH instead of 3400mAH).

Here is the discharge characteristic of this cell. For the battery, simply multiply the horizontal capacity scale by 5, vertical scale by 10, the pack is made of 10S5P array.

 

http://wooshbikes.co.uk/2019/battery/ncr-18650b.jpg

 

https://www.batteryspace.com/prod-specs/NCR18650B.pdf

Just bought a new bike with a 17amp Panasonic battery. Previous bike had a 15 amp battery which performed as I expected.

 

So far done 46 miles and only gone down one bar out of five (20%) I estimate say 30% down. That would mean something like 140 miles total range which can't be right? The meter is a King meter KM529LCD

 

Usage so far: mid power setting. Cruising speed mainly on flat roads (York) in fairly calm conditions. My weight is 88kg

 

I conclude that my battery is fantastic or the meter is misleading me?

 

Any thoughts?

 

In those conditions I would be doing just around the cut off speed so probably using about 1/3 the average Wh I get on hilly terrain (7.5 Wh/km)

 

So yes, your range estimation is correct in those conditions. Try an alpine pass and you you would probably get a quarter of that range...

Interesting stuff thanks everyone. Two further questions before my brain packs in from overload.

 

1) If the meter is simply a volt meter, and the voltage drops steadily from fully charge, then why do I have to ride 30 miles before it stops saying "FULL"?

2) If I knew ny Wh/mile figure, would that be a way of getting a reasonable idea of range? If so does anyone have some idea of how to calculate my Wh/mile figure?

 

Cheers and goodnight

I suspect that the Bosch system is a little more sophisticated than a simple voltmeter. They are monitoring the current, so measuring the charge consumption with a microcontroller is easy. I know that your comments refer to a different brand, ..but ,just putting in a word for the higher priced system

I said that his bike's battery meter was a simple voltmeter. I never mentioned Bosch and he doesn't have a Bosch because he has a 17ah Panasonic battery. Bosch is equally meaningless, but in a different way.

Edited September 22, 20196 yr by vfr400

I looked around on the IoT for you, and I am hoping this may help your understanding, as it appears to be fairly accurate:-

https://siliconlightworks.com/li-ion-voltage

It is important to note that all Li-ion cells, including the Li-ion cells contained in our Mobile Power Centers, are sensitive to voltage. A Prolonged low voltage condition within a Li-ion cell may cause the dissolution of metals (principally copper). Copper dissolves into the electrolyte solution at open circuit voltages below ~0.7 volts. This dissolved copper is re-plated within the cell upon subsequent charging and can cause undesirable effects and almost certainly will compromise cell performance (e.g. low capacity, poor cycle life, high self-discharge).

 

 

 

Similarly, high voltage can also cause the degradation of Li-ion cells, especially at elevated temperature. When a Li-ion battery is plugged into a charger, charging continues along a prescribed path until a state of charge ("SOC") of 100% is sensed by the circuitry. The charging is then terminated and the battery is allowed to very slowly discharge. It is detrimental to the cells to be kept at 98-100% SOC for prolonged periods of time (i.e. more than 10 days). This is why many cells are allowed to discharge to around 95% SOC or less before charging is re-initiated, even while connected to a charger.

 

The nature of Li-ion cells is such that the relationship between state of charge ("SOC") and voltage is fairly flat throughout much of the cell’s discharge range. A typical discharge voltage curve is shown below:-

[ATTACH type=full" alt="Li-ion Discharge Voltage Curve Typical.jpg]32172[/ATTACH]

The rapid fall of voltage at the end of the discharge cycle provides a relatively accurate means of determining when energy will run out. However, this also means that the SOC drops much more rapidly and can lead to an over-discharged condition if the cell or battery is left to sit for prolonged periods at a low SOC. This is due to the fact that Li-ion cells have an inherent self-discharge rate independent of any circuit load. This self-discharge rate is quite low at room temperatures around 20-25°C or less. Values of around 2% per month are typical. However, this rate can more than double when cells are exposed to high temperatures. Furthermore, ambient temperature can have a profound effect on the discharge voltage curve and must be considered during transportation and storage when the cells may be exposed to extreme high or low temperatures.

Well designed electronics will keep the cell(s) at somewhere between 4.2 and just under 3 volts. This is the safe "working area" for a Li-ion cell.

You can see that the battery discharges faster as it gets to the end of the charge. Just what you are noticing.

Multiply these single cell voltages by the number of cells in series in your battery.

For example, a 36 volt (nominal) battery, will have 10 blocks of series connected cells (number of cells in a block, connected in parallel is variable due to capacity and current design requirements!).

Never leave a discharged battery to its own devices for months, as the safety electronics can and will prevent further charging, and only a "Zer0 Volt Charger" MIGHT recover it, but damage will have been done.

Any questions, just ask please.

Andy

I don't know where that guy got that graph from, but it certainly doesn't represent the type of lithium cells we get in our batteries. It looks like a LiFePO4 one superimposed on normal Li-Iion battery scales.

I don't know where that guy got that graph from, but it certainly doesn't represent the type of lithium cells we get in our batteries. It looks like a LiFePO4 one superimposed on normal Li-Iion battery scales.

They do make and sell cells and batteries, so they should know quite well what they are doing.

Anyway, IMHO the graphic was there so that people could better understand the discharge of a Li-ion battery.....Some obviously do not understand it, sadly!

Please take any queries up with the web site and keep us informed of your progress, OK?

Thanks in advance

There are Li-ion SOC meters, that automatically reset themselves and re-calibrate when charging, I found one here:-

https://www.powertechsystems.eu/home/tech-corner/lithium-ion-state-of-charge-soc-measurement/

Lithium-Ion State of Charge (SoC) measurement made by coulomb counting allow a measurement error of less than 1%, which allows a very accurate indication of the energy remaining in the battery. Unlike the OCV method, coulomb counting is independent of battery power fluctuations (which cause battery voltage drops), and accuracy remains constant regardless of battery usage.

I did not see a price and its getting late, but I will investigate the method used tomorrow.

Andy

Edited September 22, 20196 yr by Andy-Mat

I don't know where that guy got that graph from, but it certainly doesn't represent the type of lithium cells we get in our batteries. It looks like a LiFePO4 one superimposed on normal Li-Iion battery scales.

He found it on "the IoT", the Internet of Things where smart machines communicate with each other. If he'd looked on the web he may have found something that made some sense.

I don't know why he thought that "it appears to be fairly accurate" and then later seemed to deny its accuracy....

But this seems to be his modus operandi, copy, paste & deny.

Andy, I used to feel sorry for you when you were called Smart Ebiker and they all ganged up on you for being proud of that bike, but now you just fill me with despair. Just like the majority of your posts, that graph is completely misleading. Some guys have suggested that you're just trolling us. Maybe you are or maybe you're just misinformed, but it makes no difference - we'd all be much better off if you just kept away from these technical matters.

He found it on "the IoT", the Internet of Things where smart machines communicate with each other. If he'd looked on the web he may have found something that made some sense...

For those interested, there is a reasonable explanation here:-

https://www.zdnet.com/article/what-is-the-internet-of-things-everything-you-need-to-know-about-the-iot-right-now/

I personally find it most useful, usually very informative, and easily understood.

Naturally, the internet as a whole has some very informative articles as well on just about everything, using both, IMHO, tends to give a really good "overview" of up to date hardware implementation, one should never forget that!

Andy

For those interested, there is a reasonable explanation here:-

https://www.zdnet.com/article/what-is-the-internet-of-things-everything-you-need-to-know-about-the-iot-right-now/

I personally find it most useful, usually very informative, and easily understood.

Naturally, the internet as a whole has some very informative articles as well on just about everything, using both, IMHO, tends to give a really good "overview" of up to date hardware implementation, one should never forget that!

Andy

From your link: "The Internet of Things, or IoT, refers to the billions of physical devices around the world that are now connected to the internet, collecting and sharing data. ", as I said the term refers to smart machines communicating with each other. Nothing to do with humans posting technical stuff.

that graph is not relevant.

John's battery is made with top grade Panasonic 18650B (3500mAH instead of 3400mAH).

Here is the discharge characteristic of this cell. For the battery, simply multiply the horizontal capacity scale by 5, vertical scale by 10, the pack is made of 10S5P array.

 

http://wooshbikes.co.uk/2019/battery/ncr-18650b.jpg

 

https://www.batteryspace.com/prod-specs/NCR18650B.pdf

As vfr400 has pointed out though, the chart on the right shows a measure of voltage vs charge used (ie coulombs used), it's not an accurate indication of voltage vs energy used since the voltage drops.

Energy used = voltage x charge used.

As the voltage drops the remaining energy drops more and more. To put it simply, the voltage will drop quicker and quicker as the battery runs out of charge if the power provided by the motor remain the same .

Interesting stuff thanks everyone. Two further questions before my brain packs in from overload.

 

1) If the meter is simply a volt meter, and the voltage drops steadily from fully charge, then why do I have to ride 30 miles before it stops saying "FULL"?

 

yes, it's a simple Volt meter

The first bar is off when more than 20% is used. The remaining charge is more than 60% but less than 80%.

The second bar is off when more than 40% is used. The remaining charge is between 40% and 60%

The third bar is off when more than 60% is used. The remaining charge is between 20% and 40%

The fourth bar is off when more than 80% is used.

The fifth and last bar is off when the battery is totally flat.

 

 

 

2) If I knew ny Wh/mile figure, would that be a way of getting a reasonable idea of range? If so does anyone have some idea of how to calculate my Wh/mile figure?

 

If you post the measure the voltage after X miles, then we can estimate the WH per mile more accurately than the rough estimate of 10WH per mile.

To put it simply, the voltage will drop quicker and quicker as the battery runs out of charge if the power provided by the motor remain the same .

yes, that's correct.

To extract the most miles, you need to reduce the assist level as the battery voltage drops and top up the power when climbing a steep section with the throttle.

I found this, this morning, which may assist anyone interested in finding and understanding a better SOC measurement:-

https://batteryuniversity.com/learn/article/how_to_measure_state_of_charge

Where this can be read, quite far down on that page:-

Coulomb Counting

Laptops, medical equipment and other professional portable devices use coulomb counting to estimate SoC by measuring the in-and-out-flowing current. Ampere-second (As) is used for both charge and discharge. The name “coulomb” was given in honor of Charles-Augustin de Coulomb (1736–1806) who is best known for developing Coulomb’s law. (See BU-601: How does a Smart Battery Work?)

 

While this is an elegant solution to a challenging issue, losses reduce the total energy delivered, and what’s available at the end is always less than what had been put in. In spite of this, coulomb counting works well, especially with Li-ion that offer high coulombinc efficiency and low self-discharge. Improvements have been made by also taking aging and temperature-based self-discharge into consideration but periodic calibration is still recommended to bring the “digital battery” in harmony with the “chemical battery.” (See BU-603: How to Calibrate a “Smart” Battery)

 

To overcome calibration, modern fuel gauges use a “learn” function that estimates how much energy the battery delivered on the previous discharge. Some systems also observe the charge time because a faded battery charges more quickly than a good one.

 

Makers of advanced BMS claim high accuracies but real life often shows otherwise. Much of the make-believe is hidden behind a fancy readout. Smartphones may show a 100 percent charge when the battery is only 90 percent charged. Design engineers say that the SoC readings on new EV batteries can be off by 15 percent. There are reported cases where EV drivers ran out of charge with a 25 percent SoC reading still on the fuel gauge.

 

Guessing a bit, but it looks like a completed unit might be the best way to go, forgetting for the moment that finding a suitable enclosure that is rider and waterproof may make it less attractive!

 

I had a quick look around on ebay for such units and found this, which may possibly be adaptable to e-bike usage:-

https://www.ebay.de/itm/Battery-Monitor-Meter-Wireless-DC-120V-100A-VOLT-AMP-AH-SOC-Remaining-Capacity/123290240242?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57925%26meid%3D2bc2d4da9a734fc7a8431050eace2bb2%26pid%3D100005%26rk%3D1%26rkt%3D12%26mehot%3Dpp%26sd%3D202381149154%26itm%3D123290240242%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851

More expensive meters, with a smaller installation size, are also available for a little more money:-

https://www.ebay.de/itm/50A-coulomb-meter-Battery-Monitor-AH-SOC-CAR-RV-Remaining-Capacity-lead-acid-12V/202381149154?hash=item2f1edb43e2:g:MRoAAOSwEN9bWKgG

I hope that some of you at least are interested, and if anyone "trys one out", do please tell us all about it!

regards

Andy

PS. The second unit is designed to be used on batteries up to 120 Volts, so it will cover most e-bikes. The 12 volts in the title is very misleading!!