How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloops?

[Viking]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

After reading my comment about the 2100 cycles, i didn't realize that DoD % could factor into how many cycles you get out of the battery. They could be 2100 cycles and you would only be discharging them to about 50% while draining them to near death may have less cycles but as you said would be more robust than the 1500 cycle Eneloops.

Yes many things come into play. That's the reason I think it's not that simple just to transfer the test results made under laboratory conditions with real life conditions.
It's no secret I personally am a little sceptical with those cycle numbers. But as said I find them useful nevertheless.

If you wanna know how they come up with the numbers. You can see it in the link below under section 7.4.1.1 ( Table 9 ).

As you can see both charge and discharge are done under gentle rates followed up by a break-in every 50 cycle. The airflow around the cells is probably better since forced ventilation is permitted to keep temp. under 35°C if necessary. The voltage will never come below 1.0 volt during discharge.

On the other hand. There isn't much resting time like there would be in almost any cases under real life conditions. And the cells will probably get overcharged before they regularly get drained down to 1.0 volt every 50 cycle. However whether this is actually damaging under these low charging rates combined with the limited period of time I think is questionable. But I'm not sure about this.


http://www.cnlumos.com/lumos/Battery Knowledge/Battery Standards/IEC61951-2-2003.pdf

 

[MidnightDistortions]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

Interesting. Yeah in real life conditions Eneloops are probably overcharged over time making them weaker, usually refreshing them remedies that problem. I'm not too worried about that as i will take Eneloops off the charger once -dV hits.

 

[Viking]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

I think it will more likely be the higher temperature , charge and discharge rates , as well as the deeper discharges and and lack of regularly break-ins , that will be the cause for poorer performance.

For example will the cells under real life conditions be inserted in a little closed compartment , very tight next to each other with no room for the heat to escape , unlike in the laboratory test.

Overcharge shouldn't be much of a problem with the right charger. Actually it should rather be less than under the IEC test I would say.

 

[MidnightDistortions]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

Yeah, that makes sense. I was reading an older post on proper care of Eneloops, here: maintaining Eneloops and seeing how leaving Eneloops sit for a few years could cause poor performance as well. Just like any other NiMHs it's best to use them. You could probably get away with using them at least once a year (refreshing/break-in) but you'd probably be better to use them a little more frequently. Regarding needing them as emergencies, most of my set is charged and ready to go and i am still getting use out of my crap cells, which i haven't used my Eneloops other than one set in my 2D Maglite.

 

[WalkIntoTheLight]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

Yeah, that makes sense. I was reading an older post on proper care of Eneloops, here: maintaining Eneloops and seeing how leaving Eneloops sit for a few years could cause poor performance as well. Just like any other NiMHs it's best to use them. You could probably get away with using them at least once a year (refreshing/break-in) but you'd probably be better to use them a little more frequently.

I have not seen any testing that would confirm that, nor any official statements from Sanyo that mentions that.

Why would an unused cell accumulate any more permanent damage than a used cell?

 

[MidnightDistortions]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

I have not seen any testing that would confirm that, nor any official statements from Sanyo that mentions that.

Why would an unused cell accumulate any more permanent damage than a used cell?

I worded that wrong, should have stated that Eneloops left unused need to be break-in/refresh to restore peak performance.

 

[WalkIntoTheLight]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

I worded that wrong, should have stated that Eneloops left unused need to be break-in/refresh to restore peak performance.

Okay, that could be. I've never checked that myself (to see if a refresh is needed for LSD cells), but I usually do it for cells that have been sitting for 2 or 3 years. At the very least, it lets me know that the cells are still good.

 

[theilluminati]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

Interesting thread; got too advanced for me (

 

[tripplec]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

I am sure you'd find Eneloop in distribution for years before being sold. Same thing and if they were not performing to spec's when purchased there would be a big problem. Especially those packaged with the dumb chargers some come with. At their price I doubt they're flying off the shelves that fast.

 

[MidnightDistortions]

Re: How does the discharge curves of Eneloop Pros compare to standard AA & AAA Eneloo

Okay, that could be. I've never checked that myself (to see if a refresh is needed for LSD cells), but I usually do it for cells that have been sitting for 2 or 3 years. At the very least, it lets me know that the cells are still good.

Yeah, i have no idea if they need it but it's one of my things anyway to fully deplete the battery yearly or so to keep them in good shape or at the very least letting me know whether they are good (makes me wish all chargers come with a fancy LCD screen and shows the mA capacity). I think it mostly depends on how often you use them and the level you discharged them at.