C9000 Question

[donn_]

I'll be finishing my first break-in on a set of Eneloop XX cells tomorrow morning, and need to know if I'm supposed to leave the cells on the charger for the '2 hours after DONE' that is recommended on normal charges.

Thanks in advance.

 

[VidPro]

A break-in charge is defined by being a long slow charge, that will always include "slow overcharge" , so there would be no reason whatsoever to have topping included. You could say topping is already included, and then some.

Which brings up another question I have.
Really what is a good Break-in MaH ammount to use for This charger and Eneloop 2000mah batteries?

If the actual rate is 2Amp pulsed very short, to do this C9000 (psudo) break-in, why would I need 16 hour? The original Idea of 16 hours, was at a Slow Rate (actual rate) , the charge acceptance is lower, or the charge efficency is low. But if the real rate is 2amps pulse, then there is no slow rate, no low charge efficency.
Why are we shooting for 60% over, when we dont have low charge efficency here?

Because I have Other chargers, i have not applied the Break-in on the c9000 yet. I cannot bring myself to do it "normal" when there is nothing normal about the break-in method used in the c9000.

I am thinking (oh no) That I can adjust the Total MaH that I input to the break-in on the eneloop cells for these reasons.
1) The eneloop has a good charge acceptance at many rates anyway.
2) Why would there be low charge acceptance at a Pulsed 2A.
3) Everybody knows that 16hours at c/10 is probably overkill in this situation.

So I am sorta looking for a break-in number to put in, that would be relative (for this charger) for what is actually needed, to reduce the overcharge or the crasy in this situation for unnessiary 3200Mah totals? some number that would be more relative to the actual charge efficency?

 

[walterwitt]

A break-in charge is defined by being a long slow charge, that will always include "slow overcharge" , so there would be no reason whatsoever to have topping included. You could say topping is already included, and then some.

Which brings up another question I have.
Really what is a good Break-in MaH ammount to use for This charger and Eneloop 2000mah batteries?


If the actual rate is 2Amp pulsed very short, to do this C9000 (psudo) break-in, why would I need 16 hour? The original Idea of 16 hours, was at a Slow Rate (actual rate) , the charge acceptance is lower, or the charge efficency is low. But if the real rate is 2amps pulse, then there is no slow rate, With low charge efficency. Why are we shooting for 60% over, when we dont have low charge efficency here?


Because I have Other chargers, i have not applied the Break-in on the c9000 yet. I cannot bring myself to do it "normal" when there is nothing normal about the break-in method used in the c9000.


I am thinking (oh no) That I can adjust the Total MaH that I input to the break-in on the eneloop cells for 2 reasons.
1) The eneloop has a good charge acceptance at many rates anyway.
2) Why would there be low charge acceptance at a Pulsed 2A
3) Everybody knows that 16hours at c/10 is probably overkill in this situation


So I am sorta looking for a break-in number to put in, that would be relative (for this charger) for what is actually needed, to reduce the overcharge or the crasy in this situation for unnessiary 16Hour?

I'm a bit confused by what you mean by this question but I'll try my best to answer it.

First about the 2 amp pulse, I'm not sure where you got that from or how accurate it is. I assume you think this because of the switching power regulators the charger uses to charge the batteries. In the case of a charger, the batteries themselves operate similarly to how the capacitors work in normal regulators, where they take the high frequency pulses and filter them into an average voltage. So really the fact that it isn't really a constant voltage/current doesn't effect it that much because it averages out to the proper current.

Now as to why the 16 hour charge at 0.1C, that is actually the IEC standard for testing the capacity of batteries (Section 7.2.1 of the IEC61951-2 document on rechargeable NI-MH batteries). The 16 hour 0.1C charge is used to account for energy lost in the from of heat so that there is no doubt that the battery is fully charged before the discharge test. This test also makes a good break in because it forces the maximum safe capacity into it twice to make the battery chemically active again.

Hope this helps answer the questions you had and thanks for reading. :)

 

[VidPro]

Oh please dont start on the "standards" thing, because those paperwork discussions go on for--ever, and they rarely help.

I will just mention, that the bal bla bla standards, are bla bla bla "Constant Current" , and somone else can debate that till the cows come home :-)

I get the information on the rate, from the OsillyScope pictures, and the general way it acts now, on all the other modes. no information I have seen would indicate that the break-in is different. Sure there are some things i assume, and assumptions made from viewing operation, but i couldnt state it was fact. . . just yet.

Mabey what I should instead be asking is : What is the lowest MAH setting you can set the c9000 for on Break-in, and still "fully" charge a eneloop 2000 that was fully discharged (with some slight overcharge assumed).

scope is here http://www.candlepowerforums.com/vb...age-measured&p=3581455&viewfull=1#post3581455
Luckily he also has a scope of the break-in. I assume these scopes are showing voltage (not current). I cross compare the peaking, and make assumptions.

 

[Mr Happy]

The 0.1C charge current is the average current. It really doesn't matter if this is a continuous low current or if it is made up of pulses. Both amount to the same thing.

When you do a break-in on an eneloop you can set the capacity to 1900 mAh or 2000 mAh. I would probably go with 1900 mAh, just because.

 

[Russel]

[...]I assume these scopes are showing voltage (not current).[...]

That is correct, the oscilloscope screen captures are showing voltage over time. In the first post there are some current measurements from a graphical multimeter.

 

[VidPro]

c9000 Break-in 160% Overkill or not?

Ok i got some first results.

The Victoms:
4 eneloops that seem to be manufactured year 2009, colored light blue, discharged and charged only ONE time before. The testing of them then was the relative ~1950mAh to the .9V cutoff with about 50mAh still left (if i discharge lower). variations between cells were very small.

Hold on there partner:
Because the cells were charged, I realised that starting a break-in on the 9000 would mean that it would charge FIRST, so I first discharged them ON the same 9000 (this time) at 500mAh, before starting the break-in. An obvious move , but that changes the ammount of times these were discharged (cycled).

The Device:
a MAHA c9000 bought way late, so it would be a later revision.
Different Break-in mode on 4 cells done all at the same time.

Break-In mAh| total | Displayed result (of capacity held same device)
1) 2000mAh | 3200 | 1965mAh
2) 1800mAh | 2880 | 1924mAh ALL display 1.44V
3) 1600mAh | 2560 | 1909mAh
4) 1400mAh | 2240 | 1879mAh

Differences from one to the next:
1) normal settings
2) 320mah less with a -41mAh change
3) 320mAh less with a -15mAh
4) 320mAh less with a -30mAh

Differance from 2000mAh setting to 1400mAh:
4) 960mAh less with -86mAh change

So from that I am assuming that 1500mAh is the number I am looking for to put in to the break-in to have a better balance of the overcharge ammount. They will then get another cycle while doing this next test.

If anyone would like to figure about the charge efficency when putting in ~2240 , outputs ~1879 , AT the known and assumed cutoff points and parameters , that would be cool. (i dont know which way to calculate it). That the capacity show on this machine, if I discharge on the hobby charger to .4V it would give me different results as to the total, and there is always the limitations of the measurements of any of the devices.

Assumptions: I assume that being fairly new (oops unused older) and not cycled or used much, that the minor difference in results when overcharged more is inconsequential, running them through a second break-in (yawn) might not show so much change from overcharges.

Where are they at now?:
As a matter of Time (available) that the charger would be parked, I ran a single cycle of the same cells, instead of just a discharge.
C9000, Cycle, all at a 1000 charge, 500 discharge.
1) 1927 mAh
2) 1900 mAh All showing 1.45V
3) 1902 mAh
4) 1912 mAh

Now that i found my magic number, and can test 4 using the same break-in numbers (1500). I can also stop and discharge them lower (in something else) to see how much "actual capacity" exists still when discharged lower.
So that means I gotta discharge them all again (yawn) before starting the break-in.

 

[VidPro]

Re: 160% Break-In overkill or not

Oh the web is so helpfull :-)
A culmination of data from different sources, claimed that charge efficiency for ni-mh is lower when the rate is lower. They were using that as one reasoning behind the 160%. some claim the efficiency to be around 60%. That is the number that bounces around my brain just from seeing that so often. Trying to find more data....

The wiki, shows one cell item (on the right of the page in the picture) http://en.wikipedia.org/wiki/Nickel–metal_hydride_battery as being 66% , and points to powerstreams data page, which says:

http://www.powerstream.com/NiMH.htm
""The coulometric charging efficiency of nickel metal hydride batteries is typically 66%, meaning that you must put 150 amp hours into the battery for every 100 amp hours you get out. The faster you charge the worse this gets.""
(might be better said, the faster you charge WHEN it cant accept the charge, the worse it gets)

BatteryU tosses this out http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride
""Below 70 percent, the charge efficiency of an industrial NiMH is close to 100 percent""
Which is logical, because in that situation/area, you have most stuff to charge still, and no overcharging occuring.

BatteryU also still has this data http://batteryuniversity.com/learn/article/Nickel_based_batteries
""NiMH also has high self-discharge and loses about 20 percent of its capacity within the first 24 hours""
With that, an assumed 10+% would dissapear just while charging for 12-16 hour, another piece of data that doesnt apply the same way to a LSD cell.

Here is a chart in this PDF for microchip, that shows a charge efficiency pic https://www.google.com/url?q=http:/...UQFjAG&usg=AFQjCNGO0gYN4Hg1thayglhCTBtn-tmqPg Although it has some odd data if you look close. The chart only shows from 97%eff and UP, and be it 1C or 1/10c it isn't different any ammount that would matter.

and here http://www.candlepowerforums.com/vb/showthread.php?315840-Charging-efficiency-of-Ni-Mh-at-0-5C
we see that nobody showed that any really low charge efficiency existed in most of the testing. Even though web data can be found that is incorrect (at least in the case of LSD)
Oh boy this is gonna be fun :popcorn: Some web data "hasn't changed since ni-cd" (copy paste) let alone since LSD cells came out. So it looks like, if I am going to have something to believe in, i am going to have to test actual low rates (constant current) TOO, and sort some of this info out for myself.

 

[Mr Happy]

Re: 160% Break-In overkill or not

Certainly charging efficiency is not a constant, but depends on the state of charge of the cell. At the beginning of the charge the efficiency will be close to 100%, and at the end of the charge it will close to 0%. For a good battery like an eneloop the charging efficiency will be high all the way up to about 80-90% of charge.

Also, the charging efficiency will be better at low rates of charge and worse at high rates of charge. This is because the internal resistance of the cell causes some current to be converted into heat, and heat is proportional to the square of the current according to this formula: W = I2​R

If the cell has an internal resistance of 0.05 ohms and I charge it at 400 mA, the heat produced will be 8 mW. If I charge it at 1.6 A, the heat produced will be 130 mW. A big difference!

Look at these two graphs:

In the first one at 400 mA charge rate the battery stayed quite cold until near the end. In the second one at 1.6 A the battery warmed up due to resistance heating over the same period. Once again the temperature rose sharply at the end once the battery was full and all the current got turned into heat.

On both graphs we may suppose the charging efficiency was very good until the temperature peaked upwards. The battery wouldn't stay cool if charging energy was being wasted.

 

[VidPro]

Re: 160% Break-In overkill or not

Rate - resistive waste
1600 - 130
0400 - 008
4 times the power, 16 times the waste

""efficiency was very good until . . .""
Which lends the question, what if I charge it only within a small area of high acceptance , using the bench supply (constant) , then discharge it back again, just to test ONE thing, slow vrses fast acceptance, when acceptance is high in general. Still leaves a bit of problem with the wiring in my setup, as the wires will have quite a bit of resistance.

Already done here via the c9000 by Mr. Happy
http://www.candlepowerforums.com/vb...i-Mh-at-0-5C&p=3657852&viewfull=1#post3657852
1000 mA - 97.7% eff
0200 mA - 98.6% eff

So I guess i am gonna repeat the same basic testing, with constant current, instead of the 9000?

 

[VidPro]

Re: 160% Break-In overkill or not Low rate Charge efficency

Stupid preface:
"Charge efficiency" I am using here is not about the curcuits, and how efficient or not they are. I am referring to what Mr Happy said best "Charge supplied vs Charge extracted" for the battery. This test is One battery, and I have a bunch of inaccurate equiptment not a lab.
I rock the cell back and forth a few times, to exercise it, in an attempt to better work with the parameters of ending the discharge at some point. Screwed up the first test, which cycled it again, and works it within the same discharge parameters.

The Test:
Discharge to 1.0V at the same .2A used in discharge during the test.
Charge .1A (aka 100mA) for 17 hours 1700mAh
Discharge at .2A to 1.0V
Capacity displayed on tenergy hobby charger 1641mAh after discharge

The other factors:
charge can be off by -+ 1%
Tenergy is optomistic in display of discharge
There is ~18mV loss across the wiring in charge (because of added meter)
There is a ~18mV loss across the wiring on discharge
Voltage when charging Max was ~1.47V
Voltage average during charge ~1.35V
There is some point where the discharge is ended 1.0V

Uhh basically, so far I see no reason to think that there is any really low cell acceptance at a low (constant) rate, with no overcharge, in the sweet area for charge and discharge.
It took about 104% more current, than the battery releaced back again in current. So when it comes to setting the current ammount only, i do not see a good reason to WAY overdo it.

But Wat about the Watts? One revelation I had about this was , I had forgot that "power is power" and if I figure the Voltages at charge and discharge , instead of blindly looking only at some Miliamp numbers, There is a pretty big "power" loss there. Take a .1V differance in charge Vs Discharge and that is . . . oh dang, i still dont know how to calculate it.

Tack on the ~.1V losses also ~2.3W in ~2.0W out at most I get ~115% in . So even when trying to figure the total possible power losses, it is nowhere near 160%. Total power is not what were setting in these chargers usually. It is important though, when talking about how efficient the cell itself is.

Other factors still not tallied: The loss on the wiring is close to the same Volts ammount, but if the resistive losses are calculated, during charge it was for 2X as long of time. The current through the charge (curcuit) is the same, because mAh setting was Via a Ampmeter in between, so that should not matter. The current loss over the wiring during Discharge is not part of the discharge ammount shown though, because the loss is before the hobby chargers metering.

 

[VidPro]

Re: 160% Break-In overkill or not

Results are in of the 1500mAh setting for break-in on 4 X 2000mAh eneloops.
This is a completly different set of eneloops, that has only been cycled once before, then again for the first test results.
as before all the ways that the C9000 act are involved.

1) test at normal rates 1000charge 500discharge
2) break-in with a 1500mAh setting
3) test again at normal rates.
4) completly discharge singularly on PR2 type bulbs to mostly flat then run 1500mAh break-in again

Test1 | Brea | Test2 |2nd break-in from flat
1906 | 2036 | 1991 | 1961
1908 | 2014 | 1971 | 1911
1880 | 1993 | 1941 | 1910
1866 | 1987 | 1942 | 1900

Why was it so high , compared to the other tests? Now I forget if I fully discharged them DUHH. so its back again. i will flatten them out completly and start again, with the break-in being first.

Added: 2nd break in with flat batteries (mostly completly discharged even beyond .9v)

 

[VidPro]

I fixed my post 11, with the "improved" metering, and attempted efficency calculations.

 

[VidPro]

Fixed post 12 with second break-in from fully discharged. More like i would have expected.

As always the more cycled they are when they are not being used or cycled, the more things change up. Assuming a break-in is done early, I attempted to do it earlier with few cycles, but it isnt the first cycle from package.
Honestly i dont really see the point to a break-in with the time it takes, although I do like fuller cycles. And i have always liked slow charging, as long as there is no overcharging over specs.

That brings up the probabilty of another test. to run this "PWM slow overcharging" at the 2000mAh (3200 total) over and over again, for days and days on end, and see if it could even hurt a eneloop. there is no indications so far that 2000 hurts anything.

 

[B-52]

On the Eneloop 2500 XX's and using Break-IN Mode:

Can you Use the standard Charge / Discharge rate i found on MaHa's help Page. 2500 mAh batteries it Showed ( Charge: 1200mA / Discharge: 600mA ) But on the Discharge Rate is it possible to Drop the Rate even Lower to say like 100mA and get even better Results or would that be a little over the top on the Battery.

What ever the best solution suggested is what i will Go with thanks a bunch B :tinfoil:

 

[SilverFox]

Hello B-52,

The Break-In mode only allows you to set the charge rate. You want to set a 0.1C charge rate. With 2500 mAh cells you would use 250 mA.

The Charge/Discharge allows you to set separate charge and discharge rates.

Using a lower discharge rate allows the cell to maintain a higher voltage during discharge. Since the program terminates upon low voltage, you will get more capacity at lower discharge rates.

The best solution is to charge your cells and use them. If you want to record an estimate of where your cells are starting at you can do a charge followed by a 500 mA discharge. Note the charge and discharge rate and figure out a way to identify the cell. Down the road when you are wondering if the cell is still good you can repeat the test and compare.

Some of us are more "interested" in battery technology than others. We would first discharge the cell using 500 mA, then follow that with an additional discharge at 100 mA. This would be followed up with a run using the Break-In function. The capacity from this would be noted and identified with the cell for future comparison.

Tom

 

[B-52]

Sounds like allot Work Tom but i understand to get the Best out of my batteries & having a Charger like the C9000 i have to learn the different processes of Battery charging.

I was so Un-Aware! of the different ways to charge these Cells when i Got my Scanner back a couple Months ago i thought you get a Charger you get Batteries put them in the Device your using say like my scanner you charge the Batteries you run them down and do the Process :whistle: all over again! But with this Forum and another Forum's help i have learned Some really neat things in a short time all that i'v tried putting together).

I'm still kind of in that i'm not sure what the hell i'm doing faze :duh2: since buying my Charger's and Batteries but again taking notes and reading these threads have helped a bunch i know i will have More Questions as i learn this New and Exciting Craft but that's why these great forums Exist..

Thanks again for all the Info you provided Tom and the info other Folks have as Well on here B :thumbsup: