Fantastic battery?!

[Deleted member 25121]

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

What is the IoT? Everything you need to know about the Internet of Things right now

Updated: The Internet of Things explained. What the IoT is, and where it's going next.

www.zdnet.com

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.

 

[Deleted member 25121]

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.

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 .

 

[Woosh]

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.

 

[Woosh]

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.

 

[Andy-Mat]

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

Measuring State-of-charge - Battery University

Explore SoC measurements and why they are not accurate

batteryuniversity.com

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:-

Battery Monitor Meter Wireless DC 80V 100A VOLT AMP AH SOC Remaining Capacity# | eBay

Entdecken Sie Battery Monitor Meter Wireless DC 80V 100A VOLT AMP AH SOC Remaining Capacity# in der großen Auswahl bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

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

50A coulomb meter Battery Monitor AH SOC CAR RV Remaining Capacity lead-acid 12V | eBay

Finden Sie Top-Angebote für 50A coulomb meter Battery Monitor AH SOC CAR RV Remaining Capacity lead-acid 12V bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

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!!

 

[vfr400]

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

Measuring State-of-charge - Battery University

Explore SoC measurements and why they are not accurate

batteryuniversity.com

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:-

Battery Monitor Meter Wireless DC 80V 100A VOLT AMP AH SOC Remaining Capacity# | eBay

Entdecken Sie Battery Monitor Meter Wireless DC 80V 100A VOLT AMP AH SOC Remaining Capacity# in der großen Auswahl bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

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

50A coulomb meter Battery Monitor AH SOC CAR RV Remaining Capacity lead-acid 12V | eBay

Finden Sie Top-Angebote für 50A coulomb meter Battery Monitor AH SOC CAR RV Remaining Capacity lead-acid 12V bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

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!!

We call them wattmeters. You can buy them from Ebay for £8. Many of us have used them extensively. That's how we learned how batteries and ebikes worked. We didn't try and copy knowledge from Battery University.

If you want to find out about them,use Google to search the forum for "wattmeter".

 

[Andy-Mat]

We call them wattmeters. You can buy them from Ebay for £8. Many of us have used them extensively. That's how we learned how batteries and ebikes worked. We didn't try and copy knowledge from Battery University.

If you want to find out about them,use Google to search the forum for "wattmeter".

Unless they use the Coulomb counting method (which a true Watt-meter does not!), they will only be fully accurate when steady or even better, when no current is being drawn.
So in normal usage they need heavy "slugging/averaging" of the display to try and reduce the effects of varying current usage, on it.
But as they are slightly cheaper, they will find many users.
For good, easily read display, I feel that you may need to possibly give out more money than you suggest, (unless of course a secondhand one can be found), and then you enter the price realm of the "Coulomb counter" power display. Which are completely unaffected by varying current taken, and do not need any form of averaging! So the display will be accurate even when using the motor, plus modern ones re-calibrate themselves at each recharge....A really good feature I find.
I even found a 50 amp version for well under 30 UK Pounds on ebay:-

50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

Finden Sie Top-Angebote für 50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

Or this one:-

100A LCD STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

STN full-viewing angle LCD screen, 360 degrees without dead ends. Clear current function. Power-down data save function, power-off when the battery power, accumulated power, etc. are automatically saved when power-down.

www.ebay.co.uk

But its only worth buying if the accuracy and steady values are really important to you.
On my bike, I just pause using the motor power for a second or so, for my (cheap) SOC meter to steady up its display, read it and carry on riding! I have got used to its readings now!
I have far too much Scottish blood to put money into any sort of "Extra" power meter other than the Chinese LCD display already on my bike!
But each to his own of course!
Andy

 

[trevor brooker]

If I knew my 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?

https://www.pedelecs.co.uk/forum/threads/how-do-i-calculate-watts-used-per-mile.31067/

 

[Deleted member 25121]

Unless they use the Coulomb counting method (which a true Watt-meter does not!), they will only be fully accurate when steady or even better, when no current is being drawn.
So in normal usage they need heavy "slugging/averaging" of the display to try and reduce the effects of varying current usage, on it.
But as they are slightly cheaper, they will find many users.
For good, easily read display, I feel that you may need to possibly give out more money than you suggest, (unless of course a secondhand one can be found), and then you enter the price realm of the "Coulomb counter" power display. Which are completely unaffected by varying current taken, and do not need any form of averaging! So the display will be accurate even when using the motor, plus modern ones re-calibrate themselves at each recharge....A really good feature I find.
I even found a 50 amp version for well under 30 UK Pounds on ebay:-

50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

Finden Sie Top-Angebote für 50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

Or this one:-

100A LCD STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

STN full-viewing angle LCD screen, 360 degrees without dead ends. Clear current function. Power-down data save function, power-off when the battery power, accumulated power, etc. are automatically saved when power-down.

www.ebay.co.uk

But its only worth buying if the accuracy and steady values are really important to you.
On my bike, I just pause using the motor power for a second or so, for my (cheap) SOC meter to steady up its display, read it and carry on riding! I have got used to its readings now!
I have far too much Scottish blood to put money into any sort of "Extra" power meter other than the Chinese LCD display already on my bike!
But each to his own of course!
Andy

Why do you keep on and on about state of charge when several of us have pointed out that there is only a loose correlation between this and range, which is what the OP is asking about? Do you not understand our posts?

 

[Andy-Mat]

Why do you keep on and on about state of charge when several of us have pointed out that there is only a loose correlation between this and range, which is what the OP is asking about? Do you not understand our posts?

I feel that you are not reading what I write, your choice of course.
It was all explained.
At the end of the day, apparently some people (not me) want to know more accurately, exactly what capacity they have left in their battery, e.g. aproximate distance left to ride before a charge is required.
What are you looking for?
Andy

 

[Deleted member 25121]

At the end of the day, apparently some people (not me) want to know more accurately, exactly what capacity they have left in their battery, e.g. aproximate distance left to ride before a charge is required.

You've done it again, battery capacity (as measured by charge alone) does NOT give even an approximate measure of distance left to ride before a charge is required.

What are you looking for?

I'm looking to answer the question that the original poster posed, namely how to relate the readings on his (voltmeter) display to range.
What's your agenda?

 

[John F]

I'm out on the bike right now. I have a basic meter at home. When I take the battery off is it obvious which terminals to connect to? I assume there are only 2 clearly marked terminals. Stupid question but I want to be clear!

 

[Andy-Mat]

You've done it again, battery capacity (as measured by charge alone) does NOT give even an approximate measure of distance left to ride before a charge is required.


I'm looking to answer the question that the original poster posed, namely how to relate the readings on his (voltmeter) display to range.
What's your agenda?

You appear to feel that we all "need an agenda" for posting here.
I feel that apparently some here have an "agenda" of being rude to other members.....
The original poster has been answered by several here already (go back and check), that the cheaper so called SOC meters/displays are sadly very often badly affected by changes in current, making them difficult to make sense of while riding.
Mostly due to their being a simple voltmeter, with no correction for current drawn.
Also, due to the almost flat discharge rate for most of the capacity of modern battery types, that also makes the display difficult to interpret for some.
But as pointed out by several, it is possible to get an "idea" of remaining capacity by "getting used" to the enigmatic display over several complete discharges of the battery!
But for anyone possibly wanting a more exact and reliable (steady?) indication of capacity, even when the normal display may wildly indicate, certain types of meter can achieve a repeatable indication, with a possible 1% accuracy, of capacity. But cost more!
How come you did not appear to understand that?
Please do have a good day, mine is really GREAT!
regards
Andy

 

[vfr400]

I'm out on the bike right now. I have a basic meter at home. When I take the battery off is it obvious which terminals to connect to? I assume there are only 2 clearly marked terminals. Stupid question but I want to be clear!

If you want to measure the battery's voltage, you stick your probes in the two outer terminals. The battery needs to be switched on.

The matter is made more complicated by voltage sag. When you use power from the battery, the voltage goes down roughly in proportion to how much power you draw, so your LCD might show the segment gone, and then it reappears when you're not drawing as much power. Also, when you stop and let the battery rest, it's voltage climbs a bit. Finally, LCD normally have a damping factor in them, so they show the moving average voltage over a period of time. That makes them behave a bit more like a fuel gauge than a voltmeter, but as long as you understand that, you can get some meaning from its display.

If you're really interested to say at which voltages your battery display loses segments, a better way id to get a 5.5mm jack, like the one in your charge socket and wire it to your voltmeter, then go out for a bike ride with your meter taped where you can see it. That will give you a real-time indication of the battery's voltage and a much better understanding of what's going on.

 

[vfr400]

Unless they use the Coulomb counting method (which a true Watt-meter does not!), they will only be fully accurate when steady or even better, when no current is being drawn.
So in normal usage they need heavy "slugging/averaging" of the display to try and reduce the effects of varying current usage, on it.
But as they are slightly cheaper, they will find many users.
For good, easily read display, I feel that you may need to possibly give out more money than you suggest, (unless of course a secondhand one can be found), and then you enter the price realm of the "Coulomb counter" power display. Which are completely unaffected by varying current taken, and do not need any form of averaging! So the display will be accurate even when using the motor, plus modern ones re-calibrate themselves at each recharge....A really good feature I find.
I even found a 50 amp version for well under 30 UK Pounds on ebay:-

50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

Finden Sie Top-Angebote für 50..400A STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

Or this one:-

100A LCD STN Hall Coulomb Meter Counter Voltage Current Power Capacity Indicator | eBay

STN full-viewing angle LCD screen, 360 degrees without dead ends. Clear current function. Power-down data save function, power-off when the battery power, accumulated power, etc. are automatically saved when power-down.

www.ebay.co.uk

But its only worth buying if the accuracy and steady values are really important to you.
On my bike, I just pause using the motor power for a second or so, for my (cheap) SOC meter to steady up its display, read it and carry on riding! I have got used to its readings now!
I have far too much Scottish blood to put money into any sort of "Extra" power meter other than the Chinese LCD display already on my bike!
But each to his own of course!
Andy

You never listen. We've actually done it! You haven't. Just understand that we know what we're talking about.

This one shows Volts, watts, amps and watt-hours. It's very accurate, though accuracy isn't important, since battery capacity is never as stated. After you've run down the battery a couple of times, you know how many watt-hours the meter says it has. That number is all you need to compare with how many it says that you've used.

 

[Andy-Mat]

If you want to measure the battery's voltage, you stick your probes in the two outer terminals. The battery needs to be switched on.

The matter is made more complicated by voltage sag. When you use power from the battery, the voltage goes down roughly in proportion to how much power you draw, so your LCD might show the segment gone, and then it reappears when you're not drawing as much power. Also, when you stop and let the battery rest, it's voltage climbs a bit. Finally, LCD normally have a damping factor in them, so they show the moving average voltage over a period of time. That makes them behave a bit more like a fuel gauge than a voltmeter, but as long as you understand that, you can get some meaning from its display.

If you're really interested to say at which voltages your battery display loses segments, a better way id to get a 5.5mm jack, like the one in your charge socket and wire it to your voltmeter, then go out for a bike ride with your meter taped where you can see it. That will give you a real-time indication of the battery's voltage and a much better understanding of what's going on.

If the OP's voltmeter is a digital one, and it reacts quickly to voltage changes (as a good one does!), it may be a bit unreadable when drawing current/using the motor - sadly!
An older "needle" volt meter will possibly be easier to read, as they are often damped, and the weight of the needle adds to the "positive" damping effect.
But who has one of those nowadays? Few and far between in my world. I miss them for some jobs!
Regards
Andy

 

[Deleted member 25121]

You never listen. We've actually done it! You haven't. Just understand that we know what we're talking about.

He'll just change the subject when questioned - oh look, he's now on about the response time of the meter.....

 

[vfr400]

If the OP's voltmeter is a digital one, and it reacts quickly to voltage changes (as a good one does!), it may be a bit unreadable when drawing current/using the motor - sadly!
An older "needle" volt meter will possibly be easier to read, as they are often damped, and the weight of the needle adds to the "positive" damping effect.
But who has one of those nowadays? Few and far between in my world. I miss them for some jobs!
Regards
Andy

As I said, there's those that theorise and there's those that have actually done it. I can tell you that he won't have any trouble reading his meter to see what's going on. All you're doing is trying to discourage him by putting fake obstacles in his path. It would be better if you stayed out of this.

 

[Nealh]

From experience John F will get to know how his LCD battery meter will indicate possible range/mileage form riding and using his bike. My KT lcd 2 has four segments and each one is approx. 25% once the last bar goes I know I have approx. 8 -10 miles left in the tank as to speak. They aren't acutely accurate but with usage and noting how many miles you have gone when each bar disappears he will soon get an idea of how to read it, one way is to ride around locally till lvc is hit and then get an idea of the lcd's reading.

 

[John F]

Ok now done 61 miles and the meter is now down by 2 bars so I think I'll check the voltage.

I note the battery has 5 terminals. The identification marks are dificult to read, but if I'm correct they are: In order they are:

TX + RX - V.

A bit nervous as to sticking the meter probes in, so lets hope + and - are in the correct places!

What are the other 3 symbols?

Thanks for evryones help. It's a fascinating subject and I'm learning a lot