Good Things To Know About Eneloops...

[Bones]

The following hyperlink leads to an article paraphrasing a Sanyo Vice-President's response to an Eneloop self-discharge test:

http://www.stefanv.com/electronics/sanyo_eneloop.html

Basically, it sets out three interesting facts that were new to me:

1. Eneloops are not necessarily charged to their full capacity when they leave the factory.

2. Several long term tests have shown that their rate of self-discharge decreases over time.

3. Every 10°C increase in temperature has the same general effect as doubling their time in storage.

Anyway, I thought it well worth a read.

 

[jtr1962]

1. Eneloops are not necessarily charged to their full capacity when they leave the factory.

I noticed that when discharging them out of the pack on my C9000. They were generally around 75% of tested capacity.

Another interesting fact to add to the list is that practically all Eneloops test above their rated capacity. I've had only 5 out of a total of 16 AAs and 8 AAAs which tested at less than capacity, but worst case was still 98.4% of rated capacity. Given the typical NiMH rating system, any other manufacturer probably would have rated these at 2100 mAh. Hats off to Sanyo for being honest.

 

[barkingmad]

Hats off to Sanyo for being honest.

Yes - all the Eneloops (quite a lot!) I have tested are around 1920-2050 - so very close to the specified 2000mah capacity and (when compared to many others) they seem to hold voltage (when loaded) better.

 

[koala]

The Japanese people are very strict about their products. They will feel terrible if their product does not work up to spec.

 

[3rdDerivative]

I thought putting batteries in the freezer was a no-no.

 

[Bones]

I thought putting batteries in the freezer was a no-no.

Energizer and Duracell say no, but there may be some advantage to freezing NiMH batteries according to Wikopedia (under the Battery lifetime header):

http://en.wikipedia.org/

Definitely advantagous to freeze NiMH batteries according to this excerpt from a physics lecture given at the University of Illinois at Urbana-Champaign:

http://img264.imageshack.us/

An historical perspective on freezing batteries thanks to the Smithsonian:

http://scienceservice.si.edu/

 

[barkingmad]

Self discharge is lower when the temperature is lower but the battery performance is lower as well if you try to use them. With Eneloop being LSD anyway I would just keep them 'cool' - i.e. room temperature.

 

[Canuke]

Self discharge is lower when the temperature is lower but the battery performance is lower as well if you try to use them. With Eneloop being LSD anyway I would just keep them 'cool' - i.e. room temperature.
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I'll be installing a small refrigerator in here shortly, for the storage of batteries and other items which wuld benefit from having their chemical activity slowed down, Eneloops and other NiMH's among them. If every 10 degrees cooler doubles the charge retention, that should be more than sufficient for me... if I needed more than that, I have too many batteries :help:

As for reduced performance under heavy load while cool, it doesn't take them long to warm up to room temps... and I'm likely to be using cells fresh off the charger in those situations anyhow.

 

[barkingmad]

I'll be installing a small refrigerator in here shortly, for the storage of batteries and other items which wuld benefit from having their chemical activity slowed down, Eneloops and other NiMH's among them. If every 10 degrees cooler doubles the charge retention, that should be more than sufficient for me... if I needed more than that, I have too many batteries :help:

As for reduced performance under heavy load while cool, it doesn't take them long to warm up to room temps... and I'm likely to be using cells fresh off the charger in those situations anyhow.

Not sure if it's a bit over-the-top for LSD batteries like Eneloops - they only lose about 10% over the first 6 months and 15% (in total) in a year.

So based on 2000mah capacity - they should still have about 1700mah after a year. If you halved the discharge rate you may get up to 150mah more storing them for a year in a fridge.

But if you used them after about 3 months - the benefit could be as little as 30-50mah?

Also I do not have the specific figures for Eneloop - but normal NiMH only give about 80% service at a few degrees above 0 C - so ''if' you were to use them soon from the fridge you may lose far more than any gain from storing them in there.

 

[TorchBoy]

I'll be installing a small refrigerator in here shortly, for the storage of batteries and other items which wuld benefit from having their chemical activity slowed down, Eneloops and other NiMH's among them. If every 10 degrees cooler doubles the charge retention, that should be more than sufficient for me...

Your call of course but that really doesn't sound like an efficient use of electricity. It would be much more efficient to just recharge them every six months instead of yearly.

 

[Daekar]

The Japanese people are very strict about their products. They will feel terrible if their product does not work up to spec.

That's why the Japanese manufacturers have splattered the Big 3 all over the collective automobile market's windshield in the last 20 years...

...And they hold their suppliers to that standard as well. Whenever we ship out medium-sized (stator housing OD ~15") electric motors to Japanese microchip manufacturing companies, they get an extra bit of attention - We Scotch-brite any hint of imperfection out of the scratch-prone soft aluminum housing of the motors and clean them within an inch of their lives afterwards - AND they get an extra sticker. It's annoying sometimes, because I've been told they'll reject a motor based purely on appearance even though it works just fine, but I figure for the money they're paying (I don't know how much, but I know the machines they go in are 1 million USD and up) they deserve it. I don't like to let anything ship to ANYBODY if it isn't exactly right.

Knowing the Japanese are anal about quality makes ME more likely to buy Japanese products.

 

[barkingmad]

That's why the Japanese manufacturers have splattered the Big 3 all over the collective automobile market's windshield in the last 20 years...

...And they hold their suppliers to that standard as well. Whenever we ship out medium-sized (stator housing OD ~15") electric motors to Japanese microchip manufacturing companies, they get an extra bit of attention - We Scotch-brite any hint of imperfection out of the scratch-prone soft aluminum housing of the motors and clean them within an inch of their lives afterwards - AND they get an extra sticker. It's annoying sometimes, because I've been told they'll reject a motor based purely on appearance even though it works just fine, but I figure for the money they're paying (I don't know how much, but I know the machines they go in are 1 million USD and up) they deserve it. I don't like to let anything ship to ANYBODY if it isn't exactly right.

Knowing the Japanese are anal about quality makes ME more likely to buy Japanese products.

Perhaps they have it right - if everyone expected / demanded better quality surely that is passed on in the products and services they are being used for?

 

[Canuke]

Your call of course but that really doesn't sound like an efficient use of electricity. It would be much more efficient to just recharge them every six months instead of yearly.

The fridge is intended to store anything that would benefit from the cooler temps, separate from the regular food fridge. It isn't meant primarily for Eneloops or batteries; if it were, you'd be right.

 

[TorchBoy]

It isn't meant primarily for Eneloops or batteries;

Phew, that's a relief. :sweat:

 

[SilverFox]

We may be missing out on a marketing opportunity...

We market a battery storage cooler, and in the fine print also mention that it can also be used for beer and food...

Tom

 

[OhMyGosh]

I just ran down 4 freshly opened Eneloop AAA's on my Maha C-9000.

nominal capacity is 800 mAH
mfg date 04/2006 were 571, 576 mAH
mfg date 08/2006 were 628, 637

I just started a 2 day break-in cycle.
I'm impressed.

I have quite a few more AAA and AA to process that are mid 2006 dates.

 

[koala]

If you are thinking of a fridge for your Eneloops and other batteries please consider that the fridge also consumes electricity. You will be better off recharging the cells than buying a fridge that leech off the grid.

If you have some space in your current fridge then why not, I say go for it. But not a new fridge for batteries. Also, not sure what sort of vapor(no warnings on the label) will the batteries release during storage so you might want to avoid mixing food and batteries. I doubt there's any but during charging the battery can give out some gas.

 

[Nubo]

That's why the Japanese manufacturers have splattered the Big 3 all over the collective automobile market's windshield in the last 20 years...

...And they hold their suppliers to that standard as well. Whenever we ship out medium-sized (stator housing OD ~15") electric motors to Japanese microchip manufacturing companies, they get an extra bit of attention - We Scotch-brite any hint of imperfection out of the scratch-prone soft aluminum housing of the motors and clean them within an inch of their lives afterwards - AND they get an extra sticker. It's annoying sometimes, because I've been told they'll reject a motor based purely on appearance even though it works just fine, but I figure for the money they're paying (I don't know how much, but I know the machines they go in are 1 million USD and up) they deserve it. I don't like to let anything ship to ANYBODY if it isn't exactly right.

Knowing the Japanese are anal about quality makes ME more likely to buy Japanese products.

Slightly different business model than China, which has given us poison pet-food and antifreeze toothpaste recently. :sigh:

 

[TorchBoy]

If you have some space in your current fridge then why not, I say go for it. But not a new fridge for batteries.

Actually koala, it can make better economic sense to buy a new fridge than to continue using an old one that you already have. It depends on insulation and the state of the seals - a new well-insulated fridge can save enough electricity that it pays for itself in a year or two. :tinfoil:

 

[koala]

I mean... 1 new extra fridge to store the batteries and etc. Yes new fridges are more efficient, and filling it up and not leaving it empty is even better.

Actually koala, it can make better economic sense to buy a new fridge than to continue using an old one that you already have. It depends on insulation and the state of the seals - a new well-insulated fridge can save enough electricity that it pays for itself in a year or two. :tinfoil: