Eneloop - Performance Details for Experts

[Bones]

The Sanyo Europe website has recently evolved into a trove of information on the Eneloop including plenty of graphs and diagrams.

Here are hyperlinks to a some of the most relevant pages:

Cover - an Overview

Capacity - Nominal, Stored and Under Discharge

Self-Discharge - Capacity, Voltage and Higher Temperatures

Discharge Currents - Performance at Higher Currents

Low Temperature - Discharge at Low Temperatures

Voltage - Operating Voltage and DSC Settings

Cycle Life - Cycle Characteristics and Comparison

Technology - Construction and Self-Discharge Reduction

Q & A - Eneloop Questions and Answers

A very detailed .pdf document entitled 'Development of Low Self-Discharge Nickel Metal Hydride Battery' from the Sanyo Technical Marketing Department:

http://www.eneloop.info ... editors.article.pdf

But one of the available graphs; this one compares the cycle life of 3 regular NiMH cells and 3 Eneloops which were basically flogged to death, albeit not to anywhere near the degree exercised by SilverFox:

I can't help but contrast the exceptional amount of information that Sanyo has disclosed about the Eneloop with the dearth of information disclosed by virtually every other brand of low self-discharge cell.

This, combined with the thus far exemplary performance, quality and consistency of the Eneloop, does seem to reflect a company that's actually deserving our business.

Here's hoping the merger with Panasonic doesn't screw this up.

 

[Cydonia]

This is quite amazing really, when you think about it, this overabundance of information in contrast to the... paucity offered by the "other" manufacturers.

But being the rotten cynic that I am… I can't help but suspect we have seen the high water mark of quality LSD NiMh cells embodied in the Sanyo Eneloop. A retrenchment into dubious and sporadic quality equivalents is all but assured in the future according to my pessimists outlook :ironic:
In other words this is all too good to last.

 

[Black Rose]

Wow, what an amazing amount of information.

Yeah, lets hope that Panasonic sees fit to keep the Eneloop alive.

 

[45/70]

Interesting links, Bones, thanks. I didn't look over everything yet, but some of the graphs are surprisingly similar to Tom's (SilverFox). Thanks to him, we've been aware of a lot of this, due to his efforts. That's not to exclude a lot of other members findings, as well.

Re: the graphs again, I always am amazed at how well the eneloop's hold up their voltage under load, as opposed to other NiMH's, including other LSDs. That, to me, is one of the best features of the eneloops. I don't think a lot of people notice, or appreciate, how this affects a battery's performance. In this respect, the eneloop's kill even Sanyo's own NiMH's.

Dave

 

[coppertrail]

Yes, thank you ,great info. Love some of the grammer "they can be used in mouses . . ."

 

[lctorana]

Quote from this website:
Even if you discharge eneloop with 4.000 mAh...

Amusing. Even the real battery professionals make this boo boo.

Fabulous website. Thanks for the links - we can fully design on paper to our heart's content now!

 

[UnknownVT]

The Sanyo Europe website has recently evolved into a trove of information on the Eneloop including plenty of graphs and diagrams.
Voltage - Operating Voltage and DSC Settings

WoW! thank you very much for the heads up on this information.

There are some pretty silly typos "accellerated"(sic) in the graph you posted, and in the link above for the Voltage "The voltage makes the differene"(sic)

Anyway all that is trivial when compared to the wealth of information.

The information at the Voltage link was very relevant for what I had been discussing over at the Pentax dSLR forum on eneloop voltage maintenance - K200D Battery Meter Problem

I'll paste what I said below -

..... by careful measurement it was determined that the cutoff voltage threshold in the Pentax K200D dSLR was about 1.15V with a max current demand of ~1.5Amps

conventional high capacity NiMH batteries will outperform eneloops if they are recently charged (ie: not stored for too long before actual usage).

Here are the comparisons - again using the discharge curves by SilverFox taken from NiMh Battery Shoot Out

I drew the same horizontal 1.15V threshold cutoff red-line
then noted the points at which the 2Amp and 1Amp discharge curves crossed that red-line and found the mid-point between those (this should approximate where a 1.5Amp curve would cross the 1.15V red-line - not exactly right but probably close enough for this look-see comparison)
and dropped a vertical red-line to the horizontal axis to note the actual Amp-Hours delivered.

eneloop

Energizer 2500 mAh

Duracell 2650 mAh

those readings were approx

Sanyo 2700mAh = 2.265 A-h
Duracell 2650mAh = 1.881 A-h
eneloop = 1.66 A-h
Energizer 2500mAh = 1.61 A-h
GP ReCyko = 1.54 A-h
RoV Hybrid = 1.43 A-h

So the high capacity Duracell 2650 mAh (and Sanyo 2700mAh) do beat the eneloop when they are recently charged and in good condition.
But the Energizer 2500mAh is lower than the eneloop even when recently charged.

However when aged high capacity NiMH are notorious for developing high rates of self-discharge and can lose their capacity (eg: Ref1 Ref2 Ref3) - so that the LSD (Low Self-Discharge) batteries eventually will cross-over and perform better in longer storage before use situations.

To be fair when one is going to use the K100D/K200D a lot - then charging up a set of those better performing high capacity NiMH on the day or night before probably will show better performance from eneloops under the same conditions.

But if the batteries are stored or partially used for anything over a month or 2, then the eneloops are probably going to do better at that point.

Also see:

summary post #57 of eneloop vs. Kodak Pre-Charged Voltage Maintenance

 

[Nubo]

Quote from this website:
Even if you discharge eneloop with 4.000 mAh...

Amusing. Even the real battery professionals make this boo boo.

Some countries use a period for grouping thousands.

http://en.wikipedia.org/wiki/Decimal_separator

 

[saabluster]

Some countries use a period for grouping thousands.

http://en.wikipedia.org/wiki/Decimal_separator

That was not the issue. He was referring to the reference to "mAh".

 

[was.lost.but.now.found]

I'd be very curious to know what battery was used as their comparison as the standard (non LSD) NiMH.

 

[Igor Porto]

I'd be very curious to know what battery was used as their comparison as the standard (non LSD) NiMH.

Probably their standard NiMH batteries. Look the pic on this graph:

 

[geek4christ]

Awesome link roundup, Bones. Thanks for posting.

 

[Egsise]

The Sanyo Europe website has recently evolved into a trove of information on the Eneloop including plenty of graphs and diagrams.

Here are hyperlinks to a some of the most relevant pages:

Cover - an Overview

Capacity - Nominal, Stored and Under Discharge

Self-Discharge - Capacity, Voltage and Higher Temperatures

Discharge Currents - Performance at Higher Currents

Low Temperature - Discharge at Low Temperatures

Voltage - Operating Voltage and DSC Settings

Cycle Life - Cycle Characteristics and Comparison

Technology - Construction and Self-Discharge Reduction

Q & A - Eneloop Questions and Answers

A very detailed .pdf document entitled 'Development of Low Self-Discharge Nickel Metal Hydride Battery' from the Sanyo Technical Marketing Department:

http://www.eneloop.info ... editors.article.pdf

But one of the available graphs; this one compares the cycle life of 3 regular NiMH cells and 3 Eneloops which were basically flogged to death, albeit not to anywhere near the degree exercised by SilverFox:

I can't help but contrast the exceptional amount of information that Sanyo has disclosed about the Eneloop with the dearth of information disclosed by virtually every other brand of low self-discharge cell.

This, combined with the thus far exemplary performance, quality and consistency of the Eneloop, does seem to reflect a company that's actually deserving our business.

Here's hoping the merger with Panasonic doesn't screw this up.

Kinda "old" news...:thinking: See My post
My link is to this place, i guess those files have been just waiting there to be "found".

 

[traveler]

Very useful!

From the graph, even eneloop drop about 50% of capacity after 300 cycles.

So if you charge/discharge battery everyday (possible if you use high power DSLR to take photos), about 1 year life span is expected.

 

[Black Rose]

Very useful!

From the graph, even eneloop drop about 50% of capacity after 300 cycles.

The charge and discharge rates in that graph are 1C (2000 mA), which is harder on the cells than what most people do; 1000 mA charge, 500 mA discharge.

 

[jhellwig]

This is quite amazing really, when you think about it, this overabundance of information in contrast to the... paucity offered by the "other" manufacturers.

But being the rotten cynic that I am… I can't help but suspect we have seen the high water mark of quality LSD NiMh cells embodied in the Sanyo Eneloop. A retrenchment into dubious and sporadic quality equivalents is all but assured in the future according to my pessimists outlook :ironic:
In other words this is all too good to last.

I would also be suspicious considering that sanyo made junk tv's for walmart for years. They even acknowledged that they were junk. They had a seperate number you called when the thing to a crap.

 

[was.lost.but.now.found]

I would also be suspicious considering that sanyo made junk tv's for walmart for years. They even acknowledged that they were junk. They had a seperate number you called when the thing to a crap.

I have a Walmart Sanyo tv from college that is 12 years old and still going strong.

 

[Muse]

Wow, what an amazing amount of information.

Yeah, lets hope that Panasonic sees fit to keep the Eneloop alive.

Panasonic (and Matsushita in general) is known for quality, durability, long product life. Consumer Reports surveys bore this out some years ago, I don't know about recent studies. Of course, in this economic climate who knows what's going to transpire? However, I just ordered 2 packs of AAA Eneloops (not to predate the Panasonic effect, but because I need some good AAA rechargables).

 

[Bones]

Very useful!

From the graph, even eneloop drop about 50% of capacity after 300 cycles.

So if you charge/discharge battery everyday (possible if you use high power DSLR to take photos), about 1 year life span is expected.
-

When you consider that those poor cells went through a complete 2 Ampere charge and a complete 2 Ampere discharge every 2 hours and 40 minutes for over 40 days and 40 nights, I think they did amazingly well.

This is especially so when you consider that they did it in an ambient temperature of 25°C, with a DeltaV of +/- 10mV, and with a measly 20 minute rest period after charging and an even more measly 10 minute rest period after discharging.

In fact, it's too bad the graph of the test results doesn't also chart the internal temperature of the cells throughout the test. It would be interesting to know the highest and average temperatures the cells had to sustain.

Anyway, as noted on the graph, this was a (grossly) accelerated test, and while it certainly proves the Eneloop can take a beating, I don't think it can be considered in any way indicative of its true cycle life. Except, of course, in an application that somewhat duplicates actual the conditions of the test.

 

[LuxLuthor]

A great resource thread. Thanks Bones and others. Including all the information at that unprotected file resource: http://www.eneloop.info/fileadmin

I love the violations of the Important ReadMe File point "B" !!!

http://www.eneloop.info/fileadmin/IMPORTANT_README.txt