The best ever solution from your help

[mountainsport]

Sorry to all,

But i just can not seem to let go regards to the good and shared BATTERY ADVICE that has been given especially to those on this top site who lack technical knowledge.

On this particular site there are so many people to name who are packed with valuable information and experiences, all combined can go as far as opening up a new PEDELECS PHASE TWO WEB SITE.

The point that i am making is, can anybody answer this difficult question for me? Right,still on the subject of batteries, is there any posibble way for us amateurs out there when just bought or planning to buy a new battery,is there anyway or meter to test the quality/integrity/capacity at present and what it has lost due to improper storage etc,to give you a basic idea to what you have?

I certainly don't mind to go as far as to removing the battery case if needed. It would be so nice to hear from you all to say, YES it is possible please help someone or two or three or even maybe four the more info the stronger i become Cheers!!!

Mountainsport. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

 

[103Alex1]

Lol. May ye grow ever stronger as knowledge is both enlightenment and empowerment. Dunno what I'd do without the members of this forum and their imparted wisdom and guidance - certainly wouldn't be sat truing a wheel at ten to two in the morning, that's for sure .

 

[smudger1956]

I have much knowledge of the energy storage and delivery system container.....

But there will be a charge for it............

 

[Jeremy]

The answer is yes, you can check the capacity of a battery, but to be a meaningful measurement it needs either a bit of patience or a special bench test rig. Either way a decent wattmeter is really needed.

The first way is to fully charge the battery, connect it to the bike via a wattmeter (Cycle Analyst, Watts Up, Turnigy or similar, with known to be good accuracy) and then go for a ride until the battery reaches its low voltage cut off point. The wattmeter should then tell you the capacity of the battery. If you fit the bike with a calibrated Cycle Analyst (and bear in mind that only the stand alone version is supplied calibrated) this becomes an easy check to make, as the Cycle Analyst has a non-volatile memory and so can keep track of capacity used over several rides. With one of the others you need to do this test in one go, noting the readings as you go, as disconnecting the power will lose the displayed data (and the battery BMS low voltage cutoff will also cause loss of data).

The other way to do it is to charge and discharge the battery using a test rig on the bench. Some RC battery chargers will do this in a very limited way, but usually don't allow discharge at a representative rate, which isn't much use practically. The bench test method will give better results, but does require a fairly hefty load. I use an alloy pot filled with oil into which I dangle an array of big power resistors, but can easily get the oil to near boiling point after an hour or so at chucking a few hundred watts into it from a battery under test. The bench test does allow data to be logged through the charge/discharge cycle though, which is useful as you can tell a fair bit about the state of a battery pack by the way things like internal resistance change with time (increasing internal resistance is a pretty good indicator of pack calendar age).

Every type of lithium cell I've tested has shown a strong age-related degradation in useful capacity, usually between 5 and 10% per year. This applies even to cells that have only a few cycles. Some cells seem to degrade very much faster, for example the first Headway LiFePO4 cells I bought lost around 15 to 20% capacity in the first year. The best cells I've seen for low age related degradation have been 18650 laptop cells, but they, unfortunately, suffer from having a high internal resistance from new.

I'd certainly be wary about buying a battery that's been sat on a shelf for a year, as you can be sure it will have lost some capacity. Proving this would be hard, though, as in practical terms loss of battery capacity doesn't really show unless you're in the habit of riding right to the point where the battery is fully discharged. Few do this, as it shortens battery life, so few would ever notice a 20% loss of capacity, for example.

 

[NRG]

MountainSport, as Jeremy posted unless there is some sort of serial number or date code scheme in place for the battery and bike you are about to purchase the only way to check capacity is to use one of the charge / discharge methods as described. There's no push button test for the majority of batteries out there, however, the Panasonic / Kalkhoff batteries do have a such a feature the Bosch may do as well...

 

[Old_Dave]

Mr Kirchhoff says... what goes in goes out, (or was it what goes out goes in) lol

So to save a bit of faffing... the "wattmeter Cycle Analyst, Watts Up, Turnigy or similar, with known to be good accuracy" can be connected in between the charger and battery

Ride the bike until discharged then charge through the wattmeter and that's 'kinda' the answer...

RC Lipo is great in this respect as the charger displays the relevelent data

 

[Jeremy]

Mr Kirchhoff says... what goes in goes out, (or was it what goes out goes in) lol

So to save a bit of faffing... the "wattmeter Cycle Analyst, Watts Up, Turnigy or similar, with known to be good accuracy" can be connected in between the charger and battery

Ride the bike until discharged then charge through the wattmeter and that's 'kinda' the answer...

RC Lipo is great in this respect as the charger displays the relevelent data

The snag with this method is that it will give an answer to within maybe 5 to 10% for a low internal resistance battery pack with a low Peukert factor, but an answer that maybe optimistic by 10 to 15% or more for a high internal resistance pack with a high Peukert factor.

Say, for example, that you have one of the small 10Ah bottle packs. We know that the very best of these (those with the high capacity Sanyo/Panasonic cells) have an internal resistance of at least 0.17 ohms when fully charged, perhaps two or three times this when nearly fully discharged. If charged at, say, 3A, then the internal resistance would absorb around 3 or 4% of the charge shown on the meter, and with an assumed Peukert factor of, say, at least 1.05 (for a pretty good LiCoO2 cell) then another 5% error will occur from this.

As a reasonable rule of thumb then I'd suggest that you might be able to estimate that a battery true capacity is around 10% lower than that shown by the total charge measured. This does depend very much on getting every cell in the pack to its minimum state of charge first, though, something that will be quite difficult to do in practice.

 

[banbury frank]

Hi The simple test anybody Can do

Run the battery flat so bike stops running then time how long it takes to Charge If you do this from NEW you will Know how the battery is performing as time goes on

to test your battery you need to know the Charging amps off the charger this is normal written on it most are 2 amps so if your battery takes 1 hour to charge then the capacity is 2Amp hours if it takes 5 then it is 10 AH this is off usable energy before low voltage cut off on BMS cuts in

Frank

 

[Old_Dave]

The snag with this method is that it will give an answer to within maybe 5 to 10% for a low internal resistance battery pack with a low Peukert factor, but an answer that maybe optimistic by 10 to 15% or more for a high internal resistance pack with a high Peukert factor.

I concur ... which is why I said "that's 'kinda' the answer..."

Its a tricky old sum

 

[Jeremy]

Hi The simple test anybody Can do

Run the battery flat so bike stops running then time how long it takes to Charge If you do this from NEW you will Know how the battery is performing as time goes on

to test your battery you need to know the Charging amps off the charger this is normal written on it most are 2 amps so if your battery takes 1 hour to charge then the capacity is 2Amp hours if it takes 5 then it is 10 AH this is off usable energy before low voltage cut off on BMS cuts in

Frank

Not really. As I mentioned above, charging losses alone mean that this method over-estimates battery capacity by at least 10%, maybe more. Add in that you can't easily ensure that all cells are equally discharged to the same SOC point before you start charging and the accuracy is undoubtedly worse.

I guess it's a good way for dealer to advise, though, as it will always make a battery seem to have a greater capacity than it really has

 

[muckymits]

Ive wondered about this for a while. Like how accurate is the gauge on the Turnigy and how much can you really expect from the battery pack. My charger will tell me I have put 8AH back in to my 12AH, so I just work it on having 10AH so will always have that l bit left to get up the last hill for home. Wish there was some easier and more accurate way of doing it.

 

[Jeremy]

Ive wondered about this for a while. Like how accurate is the gauge on the Turnigy and how much can you really expect from the battery pack. My charger will tell me I have put 8AH back in to my 12AH, so I just work it on having 10AH so will always have that l bit left to get up the last hill for home. Wish there was some easier and more accurate way of doing it.

The Turnigy meters aren't great, although the older ones could be calibrated to improve them a fair bit (they had a couple of trim pots inside). Even when calibrated the Turnigy meters tend to be a bit inaccurate at low current levels, as their internal resolution isn't great (for 120A maximum the real resolution inside the meter (not the display) is 0.117A). The Cycle Analyst is a lot better, as it has a finer resolution internally. It can resolve down to 0.01A in low current mode, although is still only OK to 0.1A in high current mode.

I designed and built a fairly simple "fuel gauge" that records battery capacity used and displays the capacity remaining on a simple meter. The resolution of the meter is only about as good as a car fuel gauge, but internally the circuit keeps track of capacity remaining in amp seconds, so has better resolution and accuracy than the Turnigy, plus it remembers the capacity remaining when you switch the bike off. Here's a picture of it on one of my bikes:

 

[Old_Dave]

Just to add that the 'Speedict' is a great tool for keeping an eye on things.... but can complicate the already complicated.

Maybe just keeping it simple like a yard stick is best

 

[muckymits]

Any build instruction for the fuel gauge Jeremy?

 

[Jeremy]

Any build instruction for the fuel gauge Jeremy?

Here you go: Endless-sphere.com • View topic - Simple ebike 'fuel gauge'

 

[NRG]

I built one with the help of Jeremy: http://www.pedelecs.co.uk/forum/electric-bicycles/7208-e-bike-fuel-gauge.html

 

[mountainsport]

Here you go: Endless-sphere.com • View topic - Simple ebike 'fuel gauge'

Hi Jeremy,

How easy is this basic meter to be installed? Is it much more easier to fit than the turnagy metres?

Mountainsport.

 

[Jeremy]

Hi Jeremy,

How easy is this basic meter to be installed? Is it much more easier to fit than the turnagy metres?

Mountainsport.

It requires a bit of electronics work, both to assemble the fairly simple circuit (NRG's link above gives a good idea of what's involved) plus the firmware needs to be downloaded to the Picaxe microcontroller that this uses.

Actually wiring it into the controller is pretty easy, just a pair of wires across the current sense shunt plus wires to the +5V supply. The hardest part is probably making sure that the ciruit is built small enough to fit inside the controller. I made a very small PCB and didn't use sockets for the ICs, which made mine a fair bit smaller than the one NRG's made, which made it easier to fit into the case.

Fitting to the bike is pretty easy, just a single length of thin 4 core cable from the display back to the controller.

Overall it's a fair bit more work than wiring in a Turnigy, but it does remember how much capacity you used on each ride between charges, even when the bike is turned off and back on several times, so giving you a pretty close equivalent to a "fuel gauge" for the battery.

 

[mountainsport]

It requires a bit of electronics work, both to assemble the fairly simple circuit (NRG's link above gives a good idea of what's involved) plus the firmware needs to be downloaded to the Picaxe microcontroller that this uses.

Actually wiring it into the controller is pretty easy, just a pair of wires across the current sense shunt plus wires to the +5V supply. The hardest part is probably making sure that the ciruit is built small enough to fit inside the controller. I made a very small PCB and didn't use sockets for the ICs, which made mine a fair bit smaller than the one NRG's made, which made it easier to fit into the case.

Fitting to the bike is pretty easy, just a single length of thin 4 core cable from the display back to the controller.

Overall it's a fair bit more work than wiring in a Turnigy, but it does remember how much capacity you used on each ride between charges, even when the bike is turned off and back on several times, so giving you a pretty close equivalent to a "fuel gauge" for the battery.

Thanks Mr J,

I dont know which one to buy now,you've made it so much easier for me to decide and i suppose for other people too.
Can you make up you mind, by just telling me what to do,why are you being so difficult?

Mountainsport.