Talk:Low self-discharge NiMH battery

Inconsistencies

The article currently contains the following two sentences in the beginning:

...the batteries retain 70 to 85% of their capacity after one year when stored at 20 °C (68 °F), while standard NiMH batteries may lose half their charge in this time period.

...Due to the low self-discharge, they (LSD NiMH batteries) are also suitable for long-term intermittent or low-current uses; they might last up to a year between charges, much better than ordinary NiMH batteries.

If the first sentence is correct, then ordinary NiMH batteries lose only half their charge in a year, so they will surely "last up to a year" which the second sentence says they don't. In my experience, I think the first sentence got it wrong. After a year, standard NiMH batteries that I owned usually lost *all* their charge, not just half. Some measurements I see now at the end of this talk page claims that the standard batteries only return 40% of the charge after just 3 months, coming out to retaining just 3% of the charge after 12 months, which is much similar to my personal experience.

So, I think the first sentence quoted above is wrong. I don't know what to replace it with, though. Nyh (talk) 14:26, 18 February 2009 (UTC)

Another quote from Nickel-metal hydride battery:

The self-discharge is 5-10% on the first day, and stabilizes around 0.5-1% per day at room temperature.

Taking the optimal numbers (5% first day, 0.5% per day), we get 10% of the charge lost after a week, 20% lost after a month, 40% lost after 3 months, and 85% of the charge lost after a year. If we take the pessimistic numbers, then 98% of the charge is lost after a year. So definitely, the sentence in our article saying that "may lose half their charge in this time period" is wrong. Nyh (talk) 14:43, 18 February 2009 (UTC)

Test results

CandlePower Forums seems like the best source of detailed technical discussions.

• Eneloop Self Discharge study
• Eneloop AA are not that good due to reduced capacity
• bulk eneloop deal
• Technical comparison of NiMH batteries

-69.87.204.16 13:51, 23 October 2007 (UTC)

Forums are never reliable sources, and should not be used for references.--Lester 11:13, 18 November 2007 (UTC)

If you are able to find better sources of more detailed, more reliable, independent test information about LSD batteries, please do share them with the rest of us! Manufacturer-furnished info is obviously potentially biased.-69.87.202.164 (talk) 22:57, 8 January 2008 (UTC)

Look at this post from CandlePowerForums for a 3. party LSD NIMH battery test. 6 different manufacturers batteries are tested for 6 months. *LSD discharge test. —Preceding unsigned comment added by 89.239.240.105 (talk) 19:23, 1 October 2008 (UTC)

Article is an advertisement, and should be deleted

Any reasons why this article should not be deleted? I think it should be deleted because:

• It serves only as an advertisement for a Sanyo brandname
• It doesn't carry information that's not also in Sanyo's advertising
• The brand is non-notable (it's difficult to find newspaper coverage of it, despite Sanyo's own claims that it's "revolutionary")
• It's notable that a new battery "separator" has enabled longer life in NiMH batteries, but that can be covered in the Nickel_metal_hydride_battery#Low_Self_Discharge_Batteries article.
• We don't need an article to cover Sanyo's specific brand of this category of battery, as there are other brands that are the same.

I created this discussion to allow a bit more than 5 days of debate, which happens if it is marked for deletion. Thanks, --Lester 00:33, 5 November 2007 (UTC)

The section about Sanyo should be removed. Motoma (talk) 14:05, 8 August 2008 (UTC)

DO NOT DELETE

Please improve the article, don't delete it. There are very few primary makers of LSD NiMH batteries, and Sanyo may be the foremost. Eneloop is their primary badge. Therefore, Eneloop is an important aspect of NiMH. But NiMH is such a big complex topic that these details cannot be adequately covered in that article. LSD batteries are sold as "pre-charged, ready-to-use", but it is clear that many factors influence how much charge they actually have when purchased -- this should be thoroughly explored somewhere in WP.

• It contains info not in any Sanyo advertising. If the tone is wrong, fix it.
• The brand is notable, as described above.
• All LSD NiMH batteries are not necessarily the same. Some would claim these are better. We come together here to try to learn the truth of such detailed claims.

-69.87.199.6 (talk) 17:54, 25 November 2007 (UTC)

There are no newspaper articles or notable technical articles about Eneloop, and nothing to state why Eneloop is different from other Low-Self-Discharge NiMH batteries. Forums can't be used as sources. It seems Eneloop is merely a brand-name of Sanyo, and there is nothing notable that sets the technology of Eneloop batteries apart from other LSD-NiMH batteries. --Lester 21:27, 25 November 2007 (UTC)

I agree that this article should be merged into Nickel_metal_hydride_battery#Low_Self_Discharge_Batteries. Palpalpalpal (talk) 09:08, 21 September 2008 (UTC)

Conflicting numbers

According first paragraph (and NiMH page), after a year the batteries retain 70-85% of their capacity. According to "Charge Retention" paragraph, batteries retain 70% after two years. It should probably be something like 60-70% after two years, but I don't know the accurate numbers.. Mar Garina (talk) 22:07, 28 June 2008 (UTC)

The self discharge of NiMh slows down with time. A LSD type might lose 15% in the first month, but out to two years still have 70% capacity remaining. 66.114.93.6 (talk) 02:39, 16 January 2010 (UTC)

Eneloop - source for "Should be charged in upright position" quote

Can anyone provide a reference for this? 161.58.16.26 (talk) 17:52, 22 July 2008 (UTC)

* "Should be charged in upright position."{{fact|date=July 2008}} deleted 26 July 2008 by 71.99.123.150. 74.208.16.17 (talk) 06:41, 26 July 2008 (UTC)

Eneloop C and D

This August 8, 2008 announcement[1] contains some "interesting" details. It seems odd that the mAh ratings of the new C and D sizes are not higher. There are many questions to ask about the new PTC over-heat protection built-in. It might increase the series resistance, particularly important during peak-surge-loads, where NiMH usually does pretty good. It could cause problems in the very fancy high-end quickest chargers. And they say that the AA and AAA sizes have also been "updated" -- how? Have the mAh ratings changed? Have they added PTC to these sizes? Are the C and D available now in the US, or only in Japan? Their new universal charger is also peculiar. It has 8 charging stations, but only 4 of the 8 fit AA/AAA, each taking one or a pair. If you charge a pair together, apparently in raw parallel, they aren't each going to be treated optimally, esp if their charge states are quite different. -69.87.203.8 (talk) 22:26, 5 September 2008 (UTC)

internal resistance

What is the internal resistance of various types of batteries?

AA cells are the most comparable between technologies. Sanyo AA NiCd are rated at 16-19 milliohms (.016-.019 ohms).[2]

There are 40 actual NiMH AA discharge data sets here.[3] Looking at the middle of the 1 Amp and 2 Amp discharge curves, the difference is generally about .05 V (about 1.20 down to 1.15 volts); the lowest are about .03 V. This implies that the effective total differential internal resistance of NiMH AA under load in the middle of discharge is about 50 milliohm (.05 ohm).

Sanyo Eneloop AA 2000 mAh LSD batteries have unusually high starting voltage under light load (.5 Amp), 1.48 V (compared to about 1.4 V for most NiMH AA batteries), and unusually high voltage under load, 1.25V at 1A and 1.21V at 2A, mid-discharge. So these would be particularly good for replacing alkaline AA batteries in equipment designed for alkaline:

1.0 Amp Test 1.871 Ah, 2.320 Wh, 112.3 Minutes

The RayOVac Hybrid AA 2100 mAh LSD batteries don't seem to have these unusual high voltages. What about other LSD NiMH batteries? -69.87.199.58 (talk) 16:08, 28 September 2008 (UTC)

Self-Discharge comparison

In 2007-2008, archae86 tested sets of LSD AA and AAA NiMH, and normal AA NiMH batteries.[4] Self-discharge was measured for up to 3 months.

These are the data for remaining capacity (mAh) (NB NOT voltage!)

initial - as supplied
1-hour - after a round of breakin cycling, then a standard charge, with a one-hour delay from end of charge to start of discharge
1-week - one-week delay from full charge to start of discharge
4-week - four weeks delay from full charge to start of discharge
3-month - three months delay from full charge to start of discharge
3m/1h% - remaining stored charge after 3 months as % of 1 hour value

AA low self-discharge NiMH
battery initial 1-hour 1-week 4-week 3-month 3m/1h%
IME 1831 2186 2053 2008 1940 89% MAHA IMEDION 2100 mAh
KPC 1723 2124 2021 1950 1874 88% Kodak Pre-Charged 2100 mAh
GRY 1687 2116 1992 1938 1872 88% GP Recyko 2100 mAh
DPC 1515 2010 1906 1857 1821 91% Duracell Precharged 2100 mAH
HYB 1619 2026 1918 1870 1808 89% Hybrio by Ultralast 2100 mAh
AMX 1645 2078 1936 1856 1784 86% Ansmann Max-e 2100 mAh
ENO 1189 2017 1904 1854 1768 88% Nexcell EnergyON 2000 mAh
ENL 1438 1980 1847 1811 1746 88% Eneloop by Sanyo 2000 mAh
RHY 1738 2021 1867 1795 1716 85% Hybrid by Ray-O-Vac 2100 mAh
RSK 1505 2024 1868 1808 1705 84% Radio Shack pre-charged 2000 mAHr
ACC 1737 2022 1899 1790 1696 84% Acculoop 2100 mAh
TPE 1009 1932 1847 1795 1590 82% Titanium Power Enduro 2100 mAh

AA ordinary NiMH
battery initial 1-hour 1-week 4-week 3-month 3m/1h%
PW20 * 1963 1804 1677 1259 64% Powerex 2000 mAh NiMH
LC20 * 1727 1595 1498 1212 70% LaCrosse 2000 mAh NiMH
KOD  * 2072 1917 1673 1012 49% Kodak 2100 mAh NiMH
SY23 * 2091 1899 1615  888 42% Sanyo 2300 mAh NiMH
TI26 * 2001 1745 1495  781 39% Titanium 2600 mAh NiMH
RAY  * 1579 1471 1273  605 38% Ray-O-Vac 1600 mAh NiMH
NEX  * 1239 1211  978  533 43% NEXcell 2200 mAh NiMH
TI24 * 2109 1859  836    0  0% Titanium 2400 mAh NiMH

AAA low self-discharge NiMH
battery initial 1-hour 1-week 4-week 3-month 3m/1h%
GR8 723 912 846 824 788 86% GP Recyko 800 mAh
IM8 727 870 810 791 758 87% MAHA IMEDION 800 mAh
EN8 600 838 783 765 734 88% Sanyo Eneloop 800 mAh
DP8 622 833 780 757 734 88% Duracell Precharged 800 mAh
AC8 543 779 724 697 632 81% Accupower Acculoop 800 mAh
HY8 593 799 738 696 594 74% Hybrio by Ultralast 800 mAh

Are there other sources of such self-discharge comparison data? It would be good to include such data and graphs in the NiMH articles. -69.87.204.244 (talk) 14:16, 2 October 2008 (UTC)

Self advertising

The external link to "Eneloop Malaysia dealer site" links to a merchant's webstore selling Eneloop batteries and chargers at lelong.com.my - a Malaysian online auction and shopping website similar to ebay. It has nothing to do with the main article besides shameless self advertise. I believe the link is vandalizing wikipedia into a personal advertising tool and should be removed. —Preceding unsigned comment added by 60.50.203.123 (talk) 23:30, 5 July 2009 (UTC)

List of brands

Can I get some opinion on this edit. The editor labeled it as "removed spam", and it's probably true that the sanyo stuff was spam, but should they have removed the list of brand names? I don't think they should, as many (although granted, not all) of the brand names were adequately referenced. I don't see how a comprehensive list of items using a technology qualifies as spam.

Opinions? James pic (talk) 15:21, 20 July 2009 (UTC)

I think the list of brands is appropriate for the encyclopedia article, but we need to be wary of doing original research. I'm hoping that a more reputable (reliable) source will cover the LSD topic, because we're badly in need of some sort of comparison for such a confusing group! LSD cells are not well distinguished from normal NiMH cells by their manufacturers, and their total capacity, self-discharge rate, and life cycle endurance vary wildly between manufacturers. Guess we'll just have to wait for a reliable source for the article, but at least keep the forum pages on the article talk page. -kslays (talk • contribs) 23:11, 27 March 2010 (UTC)

Higher Voltage

A claim about higher starting voltage was reverted. If you follow the technology as closely as I do, and based on actual experience, I'd say the reverted information is true (about the voltage at least anyway). LSD NiMh typically are more like about 1.25v than 1.2v. When stored fully charged, the voltage stays up at 1.3v for months before slowly creaping down to 1.28v. Actually by the time they even hit 1.2v under light load, the battery is 80% discharged by then. Most of the capacity is above 1.2v. 66.114.93.6 (talk) 03:43, 21 February 2011 (UTC)

Unfortunately, your actual experience is Original Research and thus the meterial cannot be included on this and your belief. If you can find a verifiable citation, then fair enough. 109.156.49.202 (talk) 18:42, 22 November 2011 (UTC)

Actually, it wasn't me that wrote it originally. I just support the idea. So that's 2 :) But, if you read the forum on candlepowerforums.com, batteries subforum, they're great knowledgeable people there. In some of their load testing of NiMh cells, there should be evidence of the higher terminal voltage of LSD NiMh cells, among other thing about batteries that should help to verify a lot of sources. 66.114.93.6 (talk) 05:43, 27 July 2012 (UTC)

First-person

"They were rated at 1900 mAh whilst other NiMH batteries from various sources that I use are rated from 2100 to 2450 mAh."

I don't think I need to explain what's wrong with this sentence.

I don't know how important this article is, but I think it's bad to the point where it should receive immediate attention regardless.174.1.201.1 (talk) 00:55, 30 May 2011 (UTC)

Fixed, but you can fix it too. It's supposed to be the encyclopedia that anyone can edit. --Wtshymanski (talk) 16:24, 30 May 2011 (UTC)

So how does it work?

It would be a very useful thing to explain how a low-self-discharge battery achieves this property. Special separators? Different alloys? Additives in the electrolyte? Amalgamation of the plates (probably not!)? What's the gimmick? Google searches have shown me nothing I can use. --21:50, 10 August 2011 (UTC)

I've just added a long list. Sorry about the delay ... Pol098 (talk) 12:56, 29 September 2022 (UTC)

Someone is manipulating this entire article (including the ratings) for promotion purposes

It's pretty damn shameful and I'd recommend it for deletion. It all reads off as advertisement that someone has tried to edit a bit in an effort to tone down the marketing speak. Half the sources lead off to some obscure forum (which I assume is not a notable source) and the links are pitiful and look like comparison provided by Sanyo. — Preceding unsigned comment added by 95.209.135.5 (talk) 01:23, 14 September 2011 (UTC)

Merge to NiMH

This is a very specific sub-category of NiMH batteries. I think it should be merged as a secti within NiMH Cantaloupe2 (talk) 19:20, 30 September 2011 (UTC)

(It's been done). Pol098 (talk) 12:50, 29 September 2022 (UTC)

Advertisement

To make this article less ad-y and more informative, I kicked off eneloop. Informations regarding Sanyo's eneloops should go there, while this article should talk in-depth about LSD NiMH batteries and their differences and advantages over NiMH and alkaline, as well as their impact on the environment. "MY LSD NiMHZ ARE BETTAZ" doesn't really help anyone who seeks informations about LSD NiMH. Merging LSD NiMH with NiMH while incorporating informations about eneloops in it's own article isn't that bad an idea either, as this article doesn't even elaborate more than "They recharge slower", rather than their inner construction etc. --TheEcoDude (talk) 17:49, 20 October 2011 (UTC)

Storage

What are optimum long-term static storage conditions for NiMH batteries? Not to maintain immediately available charge, but to minimize permanent capacity loss? Some sources say to store at about half charged, other sources say that for Ni chemistries charge state is not important. Cool temperatures seem desireable, but better not to freeze? If storing for years, would it be better to trickle charge at a very low level, to avoid full discharge? (batteryuniversity.com/learn/article/how_to_store_batteries) Different manufacturers seem to say rather different things: (www.powerstream.com/Storage.htm) There is general agreement that charging behavior after storage may be unusual the first cycle, and capacity may be regained over a few charge-discharge cycles. -96.237.13.111 (talk) 04:46, 27 November 2011 (UTC)

Firstly, batteryuniversity.com is a completely discredited source of information run, as it is by one Isador Buchmann in order to promote his equally discredited book (which is why other sources say different things). There is no such organisation as 'battery university'. The best storage regime is that prescribed by the battery manufacturer. Unfortunately, the manufacturers are rather retiscent to give too much informations which is what allows charlatons like Buchmann to spring up with apparently authoritative advice (actually rhumor and supposition mostly trawled from the internet).

In general terms, for maximum storage life, NiMH batteries should be discharged until the terminal voltage reads 0.8 volts per cell and the battery then placed in storage. Post storage, some intelligent battery chargers may have to be connected two or three times before they charge the battery. Note: that single cells can be discharged to zero volts per cell. Some manufacturers state that ideal storage is with individual cells discharged to zero volts and the cells then short circuited for storage. 109.157.161.93 (talk) 14:21, 1 December 2011 (UTC)

The accepted means of long term storage of regular NiMh cells to discharge is due to the relation of the self discharge and the inherent instability of the cell. When the cell is freshly charged, the self discharge is faster. More of the charge is lost closer to the "full" state, and then gradually slows down with time with loss of charge. The idea of storing them discharged preserves the cells in a more stable state, but they will be discharged in a year anyway. LSD cells are a bit different. Since they self discharge very slowly, the cells are inherently vastly more stable, so it is accepted that LSD cells may be stored charged if one wishes. A good quality LSD cell may take 20 years or more to loose its entire charge. Since like any NiMh cell, the self discharge slows down with time, LSD cells several years out is extremely slow.

Also I want to point out that repeatedly deep discharging the cells will do more "damage" than shallow cycling. It is due to the repeatability of the chemicals changing from one state to the other in the cycling process. When the chemicals go to one state or the other, the process errors a tiny bit, it is never 100% perfect. Chemicals end up in the wrong place, or they are converted to something else, etc. It's this accumulative "damage" that is just one factor that slowly makes the cells loose capacity with many charge cycles, which speeds up with deep cycling. When the cells are cycled more shallowly, the chemical repeatability is a bit better. However, with good quality cells, this isn't much of a concern since they will live a long time regardless. Poor quality cells on the other hand suffer more, in this way and all other degration factors. It is, however accepted to deeply discharge/cycle once in a while as it forms the cells, such as evening out the crystal structure on the plates, etc. It is a balancing act: some believe to do this or that; somebody else believes otherwise, but do one thing too often and you'll end up doing more harm than good. 66.114.93.6 (talk) 05:20, 27 July 2012 (UTC)

CalRecycle is not a reliable source

While the link is hosted on a .gov domain and well written, it is a personal report. I was not able to locate the source, but when I clicked on one of the links, I came across the disclaimer " This page is a personal perspective of a Department of Resources, Recycling, and Recovery (CalRecycle) staff person who is an avid user of rechargeable batteries." so, for wikipedia, that is not an acceptable source Cantaloupe2 (talk) 23:28, 5 January 2012 (UTC)

Article says that there are an AA cell in C and D cells.

The article says that there are an AA cell in C and D cells. However, additional information used to be there that was edited out some time ago. There are a few brands that use differently sized cells in the external shell. Such as Ray o Vac used Sub-c in their C and D. The Eneloop C and D's from japan are confirmed to be 3xAA in parallel for the D, and 4xAAA for the C. Possibly the Energizer C and D's are sub-c as well, but I'm not sure on those yet. 66.114.93.6 (talk) 05:54, 27 July 2012 (UTC)