eneloop longevity

[arjay]

So my location has recently been plagued with power outages and I dread the day that we will lose power for long periods of time (days to weeks).

I was thinking that if I was to stock up on eneloops to provide power for my flashlights and portable fans I would at least have some power.

Now if I invest on a 100 of those cells and store them until needed, how long would they last if left unused/sparingly used?

I've read that NiMH cell can only serve 5-10 years with regular use until they completely deteriorate. Is there any truth to this? I do plan to top them off every month and refresh once of twice a year.

[Battery Guy]

Greetings arjay,

100 eneloops? Do you need to power your hot water heater or something? Seriously though, you must have a lot of battery operated devices to need that many cells.

As eneloops are low self-discharge (LSD) NiMH cells, there really is no need to top them off on a monthly basis, since the self-discharge rate is only ~1% per month, unless you want them always to be >99% SOC (state-of-charge).

The tougher question is in regards to longevity, or calendar life of the eneloop. I believe that the eneloops have only been out on the market for just over two years. There is a good chance that even Sanyo does not have real aging data for 5+ years on these. So you need to rely upon anecdotal evidence from users, and a little of what we know about the chemistry differences between the eneloop and "standard" NiMH cells to make an educated guess as to their longevity.

The anecdotal evidence on CPF indicates that users have had very good luck with eneloops over the last two years, with few (if any) going bad even with relatively heavy use.

From a chemistry standpoint, the changes that Sanyo made to the eneloops to reduce self-discharge should actually improved longevity. This includes an improved separator and the elimination of manganese from the metal hydride alloy.

My best "educated" guess is that you will be good with these cells for at least 5 years. My gut tells me that you might get 10 years, but there are too many unknowns to really know.

I hope this helps.

Cheers,
BG

[Mr Happy]

Some of us have Eneloops with a manufacturing date of 2006. These 2006 cells still perform quite adequately, having perhaps lost 100 mAh of their original capacity over that time, giving 1850 mAh instead of the expected 1950 mAh or so. However, the 2006 cells in my collection that perform worst are the ones that gathered dust in a warehouse for a long time before being purchased. For all I know those cells were subjected to extreme temperature cycling or some other kind of abuse while in storage.

I suspect that if freshly manufactured Eneloops are cycled once a year and stored in a good environment (perhaps in an air-tight container in a refrigerator) then they will last better.

Note: When 2006 Eneloop packages have been opened for the first time and the cells tested three years after manufacture they have been found to hold a good charge of about 1450 mAh with a very low variation in charge and voltage between cells. (Cells fresh off the production line usually come with a charge of about 1700 mAh.) This compares with garden variety NiMH cells that would usually be found DOA after three years in a warehouse.

[Lynx_Arc]

invest in a car charger so you can charge batteries daily if needed and get a few lithium primaries for backup so you won't have to worry about them for 10-15 years unlike having to cycle alkalines due to fear of leakage. I went through a 4.5 day power outage here in 2007 before I had any LSD cells and used up 32 AAs I charged 8 of them every day running errands in my car. I used the same 16 batteries for 4 days just kept recharging them between two lanterns and a few lights and other dim lights using alkalines at that time as the nimh would discharge too much over 6 months to use them. I recommend if you can charge daily having 2.5 times your daily usage of LSD batteries and 2 times primaries. Alkalines would be good but I wouldn't buy more than you use in 2 years of them due to leakage concerns.

[Burgess]

Just FYI --


Sanyo Eneloops have been around for 5 Years now.


They introduced their "Eneloop Tones" multi-colored sets (Limited Production)
to celebrate their 5 year Anniversary. (these are the new 1500-cycle design)


I first purchased Eneloops on 07/06/2007, from Circuit City.
These were all manufactured 15 months prior -- in early 2006.

Every single one of these cells still performs admirably !

Truly Amazing Performance !


I feel that Sanyo Eneloops are a Revolutionary Product.

Just wish we could buy 'em in their C and D sizes -- in USA.


_

[arjay]

Thank you for your input guys. I think I'm one of the first users of eneloops as I got my first pack way back September of 2006 and they are still performing well till now.

I just pulled the trigger on 100 cells plus a maha c9000 to keep those batteries in check. I think I got a good price too, just under 9$ for a pack of 4AA

[Bones]

As indicated by Burgess, the Eneloop was announced on 01 Nov 2005 and released to the market on 14 Nov 2005:



Who knew then that almost five years on reports of sub-standard performance and/or failures of any sort would remain virtually non-existent for that rather plain little cell. A stark contrast to its immediate predecessors, the mighty 'high-capacity cells' typified by the Energizer 2500mAh.

[don.gwapo]

Hello kabayan,

Wow, 100 pcs. of eneloop. I must say you really want to be prepared. But I agree with you. Power outage is common in our country especially in the provinces, coz that's where I live. It will even took more than a week for the power to restore if a typhoon hits. So 100 pcs. is surely adequate.

[Arcus Diabolus]

Hail fellow pinoy! Where do you buy your eneloops? I can never find them in at SM and I only found 1 pair at greenhills. I would suggest you buy a generator for those long outages. I'm from the provinces and have experienced my share of power outages. 100 eneloops, wow thats alot of gadgets, though you'd might want to add some lithium primaries to that just in case.

[Apollo Cree]

A smaller number of eneloops, 12 V deep cycle marine batteries, a GOOD smart marine battery maintainer and a 12 V powered NiMH charger will give you MUCH more capacity at a much lower price. Plus it will have the capability of powering higher current devices.

[arjay]

Hello kabayan,

Wow, 100 pcs. of eneloop. I must say you really want to be prepared. But I agree with you. Power outage is common in our country especially in the provinces, coz that's where I live. It will even took more than a week for the power to restore if a typhoon hits. So 100 pcs. is surely adequate.

I live in the island of Mindanao, we were most unfortunate last summer as we are highly reliant on hydroelectric dams for power. We had 12-18 hours rotating blackouts for two whole months! I expect that to worsen in time as the demand is growing faster than they can put up new power plants. I just want to be prepared.

[arjay]

Hail fellow pinoy! Where do you buy your eneloops? I can never find them in at SM and I only found 1 pair at greenhills. I would suggest you buy a generator for those long outages. I'm from the provinces and have experienced my share of power outages. 100 eneloops, wow thats alot of gadgets, though you'd might want to add some lithium primaries to that just in case.

I used to get mine at the camera shops at Hidalgo when I was still a student in Manila. But now that I've moved back to my hometown in Mindanao, I found a good source for them online that ships nationwide. I'll shoot you am PM with his contact details.

I do keep a 10KVA standby genset with about 60 liters of petrol but it's too costly to run unless I want to use the A/C. Also have a stockpile of lithium primaries as my last resort. I like to be prepared.

[arjay]

A smaller number of eneloops, 12 V deep cycle marine batteries, a GOOD smart marine battery maintainer and a 12 V powered NiMH charger will give you MUCH more capacity at a much lower price. Plus it will have the capability of powering higher current devices.

As much as I would like to go with the deep cycle marine batteries with a GOOD float charger for power, those are close to impossible to source locally. All the "battery specialists" that I've called don't even know what a deep cycle marine battery is. Buying it online and Having it shipped to my location would cost too much as freight charges are crazy expensive here.

[fishinfool]

Kumusta mga Kaibigan! Hearing about all those power outages in the Philippines brings me back to when I lived there in the 70's and 80's. As kids, we loved typhoons because there was no school for days and loved power outages because we could play outside all day and night long. Now I wanna go back home. It's been waaaaaaay too long.

Going back to semi-topic, if I had back then, the batteries and flashlights I own now, I would have been King of the World.............
I mean King of Baguio!

[Arcus Diabolus]

... I'll shoot you am PM with his contact details.

I do keep a 10KVA standby genset with about 60 liters of petrol but it's too costly to run unless I want to use the A/C. Also have a stockpile of lithium primaries as my last resort. I like to be prepared.

No need... I can't buy online,. Now thats prepared!

Kumusta mga Kaibigan! Hearing about all those power outages in the Philippines brings me back to when I lived there in the 70's and 80's. As kids, we loved typhoons because there was no school for days and loved power outages because we could play outside all day and night long. Now I wanna go back home. It's been waaaaaaay too long.

Going back to semi-topic, if I had back then, the batteries and flashlights I own now, I would have been King of the World.............
I mean King of Baguio!

I love typhoons for that too! And the reason to use my flashlights!

[ryanandty]

Hey! A friend of mine grew up in Baguio! He even brought me back a locally made keychain last time he went (totally cheesy, right?). CPF sure does cast a wide net.

[arjay]

Kumusta mga Kaibigan! Hearing about all those power outages in the Philippines brings me back to when I lived there in the 70's and 80's. As kids, we loved typhoons because there was no school for days and loved power outages because we could play outside all day and night long. Now I wanna go back home. It's been waaaaaaay too long.

Going back to semi-topic, if I had back then, the batteries and flashlights I own now, I would have been King of the World.............
I mean King of Baguio!

Typhoons?! I don't need no typhoons to get power outages. Just today we already had two blackouts, one lasting 4 hours and another about an hour. The power grid is just unreliable! You might think that I'm living a flashaholics dream but its gets old fast if you have to endure that every single day.

King of the world eh? I think I'm the King of Zamboanga then! I like to go outside with pockets full of flashlights and batteries when the power goes out at night and turn them all on the same time, I get to literally light up our part of the neighborhood.

[Turbo DV8]

Just today we already had two blackouts... The power grid is just unreliable!

Where's Enron when you really need 'em?

[etc]

I have them, dated Sept 2006 and I think I've lost some capacity. I have been running that new Malkoff M31 module and the runtime has not been that great, with some cells I got under 1 hour whereas some got more like 1.5 hours on 2xAA Eneloops.

However with some Eneloops I get greater runtime than with others. So it looks like some cells dropped in capacity more than others. Also I have a few cells that get hotter than others when charging.

I believe NiMH degrades from age, not from number of charges.

[WDG]

I use a mix of 76 AA Eneloop cells purchased in 2007 and 2008. The 2007s typically rate from 1850 to 1900mAh, with internal resistances of 1.60 to 1.65VDC. The 2008s typically rate 1900 to 1950mAh, with internal resistances of 1.50 to 1.58VDC.

Out of all those, I have exactly one cell that seems a bit off, rating at 1750mAh. IIRC, the IR was about 1.65VDC on this one. This is also the only cell of the bunch with a slightly dented in base, so I'm guessing it got dropped on its butt.

The 16 AAAs I have are also mixed ages, but nearly all around 840 to 850mAh, with higher IRs from 1.85 to 1.95VDC.

Seems to me they're aging most gracefully.

[JET YCOY]

GOOD TO KNOW NA MAY MGA PINOY DIN PALA DITO. KEEP IT UP! FLASHAHOLICS

[arjay]

I use a mix of 76 AA Eneloop cells purchased in 2007 and 2008. The 2007s typically rate from 1850 to 1900mAh, with internal resistances of 1.60 to 1.65VDC. The 2008s typically rate 1900 to 1950mAh, with internal resistances of 1.50 to 1.58VDC.

Out of all those, I have exactly one cell that seems a bit off, rating at 1750mAh. IIRC, the IR was about 1.65VDC on this one. This is also the only cell of the bunch with a slightly dented in base, so I'm guessing it got dropped on its butt.

The 16 AAAs I have are also mixed ages, but nearly all around 840 to 850mAh, with higher IRs from 1.85 to 1.95VDC.

Seems to me they're aging most gracefully.

How do you measure internal resistance? Do I need a special device or something?

[Random Guy]

I use a mix of 76 AA Eneloop cells purchased in 2007 and 2008. The 2007s typically rate from 1850 to 1900mAh, with internal resistances of 1.60 to 1.65VDC. The 2008s typically rate 1900 to 1950mAh, with internal resistances of 1.50 to 1.58VDC.

Out of all those, I have exactly one cell that seems a bit off, rating at 1750mAh. IIRC, the IR was about 1.65VDC on this one. This is also the only cell of the bunch with a slightly dented in base, so I'm guessing it got dropped on its butt.

The 16 AAAs I have are also mixed ages, but nearly all around 840 to 850mAh, with higher IRs from 1.85 to 1.95VDC.

Seems to me they're aging most gracefully.

Resistance is measured in ohms, not volts.

[Mr Happy]

How do you measure internal resistance? Do I need a special device or something?

The readings quoted by WDG would be the initial test voltages reported by the C9000 when you place a battery on charge. This voltage is proportional to the internal resistance of the cell and is a fairly good health indicator.

Resistance is measured in ohms, not volts.

See above.

[arjay]

The readings quoted by WDG would be the initial test voltages reported by the C9000 when you place a battery on charge. This voltage is proportional to the internal resistance of the cell and is a fairly good health indicator.

Wow! that got me excited, I'm expecting a c9000 together with the eneloops I ordered which are due to arrive tomorrow. What else can this amazing charger do? recharge my car batteries? Seems like I need to get my hands on more of those to keep my 180 eneloops happy and healthy(runs out and sells kidney!)

[olephart]

I use a mix of 76 AA Eneloop cells purchased in 2007 and 2008. The 2007s typically rate from 1850 to 1900mAh, with internal resistances of 1.60 to 1.65VDC. The 2008s typically rate 1900 to 1950mAh, with internal resistances of 1.50 to 1.58VDC.

Out of all those, I have exactly one cell that seems a bit off, rating at 1750mAh. IIRC, the IR was about 1.65VDC on this one. This is also the only cell of the bunch with a slightly dented in base, so I'm guessing it got dropped on its butt.

The 16 AAAs I have are also mixed ages, but nearly all around 840 to 850mAh, with higher IRs from 1.85 to 1.95VDC.

Seems to me they're aging most gracefully.

I recently bought 8 "new" duraloops from a clown on the b/s/t forum. They turned out to be late 2007 manufacture. The capacity is about what WDG stated (1750-1850), but the voltage sag under load is pretty bad. They spend over half of their run time well below 1.2V with a 500mA load.

Comparing voltage to the various published charts, these cells most closely resemble charts for 5A loads rather than 500mA loads. I don't know if age is a factor or they are used/abused cells.

[WDG]

The readings quoted by WDG would be the initial test voltages reported by the C9000 when you place a battery on charge. This voltage is proportional to the internal resistance of the cell and is a fairly good health indicator.

What he said!

I didn't even know the MH-C9000s gave this kind of information when I first got them. It was from reading through CPF that I discovered it, and how useful it is. Here's a page that gives a good explanation of what the numbers mean: Interpreting Maha MH-C9000 Impedance Check Voltage linked from TakeTheActive's TTA's Picks for Best Answers to Rechargeable Battery Questions

[arjay]

I didn't even know the MH-C9000s gave this kind of information when I first got them. It was from reading through CPF that I discovered it, and how useful it is. Here's a page that gives a good explanation of what the numbers mean: Interpreting Maha MH-C9000 Impedance Check Voltage linked from TakeTheActive's TTA's Picks for Best Answers to Rechargeable Battery Questions

Thanks for the links! seems like I need to do a lot of readings. I just got my c9000 and batteries today.

Wonder if I should do a capacity test on all of them just to see how consistent these eneloops are. I got 80 AA's and 20 AAA's all with the same production code thus were produced in the same batch. Has anybody performed a test like this with this big of a sample size?

[fishinfool]

Thanks for the links! seems like I need to do a lot of readings. I just got my c9000 and batteries today.

Wonder if I should do a capacity test on all of them just to see how consistent these eneloops are. I got 80 AA's and 20 AAA's all with the same production code thus were produced in the same batch. Has anybody performed a test like this with this big of a sample size?

If you have the time and/or just want to experiment like I do, then go for it. I have over a hundred eneloops and duraloops (accumulated over 8 months though), all of which I've done break-in's right out of the package, used them, charged, discharged and r/a'd them several times, and they all have produced very consistent numbers.

If you do a capacity test on all of them, I'd love to see the numbers just to compare them to mine. But since you have 100 eneloops I guess we'll see them numbers in about 3 weeks or so.

[arjay]

If you do a capacity test on all of them, I'd love to see the numbers just to compare them to mine. But since you have 100 eneloops I guess we'll see them numbers in about 3 weeks or so.

3 weeks? try 3 months. I plan to do discharge>break-in>discharge>break-in on each set to bring them to full capacity. 4days/setx25 =100days now I can cut that in half if I can get my hands on another c9000