Rechargeable AA battery shoot out

[davidefromitaly]

ciao davide!! sono teo_92 di cpfitalia....per favore contattami via mail che non so più cosa fare per entrare nel forum italiano e mi serve un e-mail di un utente dato che sono interessato ad una sua inserzione...la mia mail è: [email protected]
fammi sapere al più presto per favore....grazie mille!!

i'll send you a PM

here and on the first post the links for the updated datas... the shoot out go on

uncompressed file

http://www.speedyshare.com/files/20922732/ultimate_battery_shoot_out.xls

compressed file

http://www.speedyshare.com/files/20922733/ultimate_battery_shoot_out.xls.7z

 

[davidefromitaly]

i have start to charge the powergenix ni-zn

during charge at 1A the voltage rise istantly at 1.9V, i have dropped the current gradually during charge for stay under 1.9V, during the charge the battery remain really cool

i have also try to overcharge the battery, i give around 150-200mAh more and the voltage raise at 2V and the battery leak a bit

so, like li-ion/poly batts, they don't absorb the overcharge, this mean that is dangerous a serial charging but is absolutely safe a parallel charging

 

[berry580]

Re: Ultimate AA battery shoot out

hi, thank you for all your efforts in this AA shoot out. For the people who has trouble understanding the technical figures, can you make a brief conclusion with your findings?

So what's not and what's not?

thank you alot! =D

 

[Linger]

Re: Ultimate AA battery shoot out

+1 How have the ni-zn cells held up for your tests?

(beside the topic rant re: methodology - If everyone tests under the industry standard why does David need to repeat them? surely all these cells have already been tested under the IEC so in interest of completleness some one else's results (battery station's?) could be posted as an additional table. But spare David the trouble of all those 16h charges and lets praise the man for documenting performance in quick charges, long wait times, and rapid(ish) discharges. Yes to replicate flashlight use some down-time could be used between bursts - this could be highly illuminating if some recover to a markedly higher rate.
Yes David made up his methods, and if he applies them accurately and consistently then I feel a lot of good comes from the work he's put into it.)

 

[MattK]

Re: Ultimate AA battery shoot out

My 'beef' is that David has repeatedly made any number of perjorative posts about various cells not attaining their rated capacity - under his testing. Since he is using an entirely different test methodology than the ones used by the factories to generate their specifications, a standardized, published and universally used methodology, I believe his claims to be unfair and innacurate.

You might want to read the entire thread. I addressed this very clearly early on:

It's fine and even desirable to do other tests but it's irresponsible and dishonest to claim cells do or do not make their rated capacities, as you have done in other threads, based upon a methodology of your own creation when the factory rated capacities are based upon an accepted STANDARD which is in use industry wide.

Again, your posts are misleading using the term 'real' since you aren't using the 'real' standard for battery capacity measurement.

Real: 'You keep using that word; I do not think it means what you think it means.'

 

[davidefromitaly]

i think to end the first part of the test in 15-20 days. i will post some reasuming tables with the original datas

btw some batts that i have don't match the rated capacity, i don't think is a my error, i can't do the same error for 4 batteries... maybe i have some damaged cells and other people have them in good condition with 100% capacity. some cells was deep discharged out of the blister, may be this can had damaged them

 

[snakebite]

what keeps prompting for a login?

 

[Linger]

Matt K,
You're totally right. Initially I had read the whole thread, from beginning on through to the end. But I didn't take notes and some details (like unsubstanciated references to a 'real') were forgotten when I got to posting 3pgs later.
My original post edited.

I take the middle - True it is hard to counter a manufacturer's claim with-out replicating her/his methodology. 'Actual capacity' of cells cannot be stated with-out reference to the testing conditions that those capacities where derived under. But the manufacture rated specs are almost a red herring as rating by the IEC standard may not be reflective of cells performance in the wild.
As such I feel the info the OP produces here may be qualitatively more useful than the official specs (I'll give him benefit of the doubt on internal validity of his study and presume accurate / reliable methodology. It would take independent replication for external validity to be established)
I rank my own cells by their performance in my applications (which places a '2000mah' rated cell above a '2650mah' rated one)

 

[Black Rose]

what keeps prompting for a login?

old4570's picture host (post #8)

 

[MattK]

Linger - As I stated above I have no problems with other testing methods; my issue is using those results to declare a capacity real or fake. Inevitably the standards used here will be much more demanding; much higher discharge rates, less than perfect charge rates, etc, and I'm fine with that so long as the results are not used libelously.

 

[JimmyM]

The problem with different discharge rates used for calculating results is that the effect of Peukert's Exponent (PE) is something I haven't seen discussed. Ideally, batteries would have a PE of 1.0, however they do not. The PU varies between batteries of different design even if they have the same chemistry. Therefore capacities derived using different methodologies cannot be compared to each other with anything other than anecdotal correlation. Tests done by one method are no more "real" than tests done using another method. If my testing method only discharges cells at 0.01C, the delivered capacity will be higher than those done with a 1C rate. Are they Real? Sure they are. But can't be correlated to other tests done with different rates. The ONLY way to compare results between tests is to perform the EXACT same test on the cells every time. That's what the IEC standard is for.
I gotta side with MattK on this. His results are valid, per his methods, but results derived using them cannot be compared, nor judgments made, regarding even the same cells using another testing method.

 

[davidefromitaly]

http://www.speedyshare.com/files/22376163/brand_new_test.xls

finally i have concluded the first part of the test. here you can find the datas about the first 4 charge/discharge cycles. i have left in spreadsheet format so you can sort datas as you want

next step will be to test them after 17 cycles so they will be perfectly formed

ps
don't take in count the datas for ni-zn cells, there is an error and i must correct it. the other cells are correct

 

[beamis]

Linger - As I stated above I have no problems with other testing methods; my issue is using those results to declare a capacity real or fake. Inevitably the standards used here will be much more demanding; much higher discharge rates, less than perfect charge rates, etc, and I'm fine with that so long as the results are not used libelously.

I don't believe it's libel to state the battery X does not hold Y capacity when used in typical fashion. If a car company advertised that their car got 50 miles to the gallon on a flat track at 6 mph with a tailwind, I wouldn't endeavor to reproduce those conditions to test their claims. I would drive the car in conditions that were typical and see what the results were. If it turned out that the car got 15 miles to the gallon in real world driving, I would rate it as a dud and it wouldn't be libelous to say so.

His results are valid, per his methods, but results derived using them cannot be compared, nor judgments made, regarding even the same cells using another testing method.

I don't believe that was his intention (to compare with other methodologies). I believe the intent was to say, "battery X is rated at Y in their 'lab' conditions, but in real world use they are more like Z."

 

[davidefromitaly]

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[Paul_in_Maryland]

3-way rechargeable AA battery shoot out at Engadget

Engadget today reports on its shootout between Eneloop NiMH, Energizer NiMH, and PowerGenix NiZn AAs. Tested in electronics--camera flash, keyboards--the three brands were found to be more similar than different.

 

[JaguarDave-in-Oz]

Re: 3-way rechargeable AA battery shoot out at Engadget

That's an awful lot of work testing all those batteries Davide. Good on ya, well done.

 

[MattK]

I don't believe ...

Please read the entire thread.

 

[JimmyM]

I don't believe it's libel to state the battery X does not hold Y capacity when used in typical fashion. If a car company advertised that their car got 50 miles to the gallon on a flat track at 6 mph with a tailwind, I wouldn't endeavor to reproduce those conditions to test their claims. I would drive the car in conditions that were typical and see what the results were. If it turned out that the car got 15 miles to the gallon in real world driving, I would rate it as a dud and it wouldn't be libelous to say so.



I don't believe that was his intention (to compare with other methodologies). I believe the intent was to say, "battery X is rated at Y in their 'lab' conditions, but in real world use they are more like Z."

Define "Typical use", Define "Real world driving" You're actually proving my point for me.

 

[davidefromitaly]

these are datas after 30 days from the last charge, the percentual isn't calculated from the labeled capacity but from the capacity i have read after 24h from the charge at 1A of load

please note that the first four batts give some strange datas... i think cause they are still in forming condition

 

[beamis]

Define "Typical use", Define "Real world driving" You're actually proving my point for me.

Typical use in my mind is a use that more closely reflects the load placed on batteries in devices like flashlights, radios, headlights, and other relatively high-current, intermittent use devices. That along with more typical charging regimens like 1A or 2A and then sitting for a day or a week before use. It doesn't have to be spot on, just MORE close than a 0.2C discharge within an hour of a 16-hour dumb charge.

Perhaps your point is that not everybody uses their batteries in the same way? If that's the case, no testing regimen is more accurate than any other. All you can do is find one that more closely resembles your pattern of usage. I suppose if you only use dumb chargers for a 16-hour charge and run a TK40 with 32 AA batteries to keep the discharge down to 0.2C the industry standard ratings will give you the information you need. My point is that if everyone only tests batteries in one regimen we'll never really have a good idea how they'll function in our various devices, and it's ok to say battery X sucks because it's rated as Y mAh, but only delivers Z mAh at 3A.