The secrets of eneloop batteries

Jan Panteltje · 2012-09-22T12:21:25+00:00

The secrets of Eneloop batteriesIn 2010 I bought a lot of Eneloop batteries,and these are in everything I use, AAA and AA.These rechargable batteries are supposed to have very low self discharge,say still 80% full after a year, come charged, and are cool for in digitalcamera,as normal rechargables are always empty when you need them.OK, some weeks ago, and I charge these with some Duracell charger,one cause the LED on the charger to flash indicating 'bad battery'.And indeed it would not even power my mp3 player.I had spare, but last week the second and third caused the same problem.So, I ordered new ones, but kept those 'defective' batteries.Then yesterday, as I was very curious as to WHY those batteries 'failed',and the new batteries came with a link to realized it could not have been too many charge-discharge cycles...So what?Put one on the voltmeter, no voltage ???Well measured if it still did any short circuit current: 530 mA (AAA).that made no sense, no voltage - no current says Ohm.Tried the next one, exactly the same!Found voltmeter lead in probe was lose...Soldered it, 1.something volt, same current.That makes about 2 Ohm Ri, and not 20 milli Ohm as Eneloop claims.So they must then be simply EMPTY????OK, put one on the lab supply, 80 mA for 16 hours, and voila, full again andworking!But I did notice I had, to get 80 mA into that AAA, set for 1.6V or highercharging voltage.Studying the Eneloop datasheets (same site under pulldown menu),shows indeed that charging voltage may be as high as 1.7V for cold environment,and 1.6 for room temperature.The discharge voltage is normally higher than 1.2V, more like 1.28V for lowloads.What I think happened is that the Duracell charger refused to charge above 1.5V,and that the cell, in spite of being empty, needed that much voltage.Or maybe me shorting it for the short circuit current test changed something inthe cell.Anyways the things, with their higher output voltage than the normal 1.2Vmake for much longer use in my...

Sep 22, 2012 44 Replies

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dagmargoodboat 13 years ago

r...

camera a bit more 'ready to shoot'.

NiZn, and it

e datasheets,

ention mWh,

iMH).

ger before dropping to 1.1 or 1.0 V

The NiZn cells deliver ~1,500mAh x 1.7V nominal discharge voltage =3D

2,550 mWhr. A typical low self-discharge NiMH is ~ 2,000mAhr x 1.25V =3D 2,500mWhr.

In my devices NiZn lasts a lot longer than NiMH because the switchers are so much more efficient at the higher input voltage.

So, rating in mWHr seems very fair.

become competitive it seems.

They're certainly environmentally attractive. Hopefully they'll get refined/perfected over time.

-- Cheers, James Arthur

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Jan Panteltje 13 years ago

On a sunny day (Tue, 25 Sep 2012 17:07:06 -0700 (PDT)) it happened snipped-for-privacy@yahoo.com wrote in :

Hey, for the case where a SWITCHER is used, you are right. But Mr consumer may put it in a flashlight, and use it until it looks like a glowing nail.... Those wire type bulbs behave a bit like a current source too.

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dagmargoodboat 13 years ago

You mean fire-bottles? (Do people still have those?)

The NiZn isn't gonna work in those. 1.8v isn't good for them!

-- Cheers, James

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Jan Panteltje 13 years ago

On a sunny day (Wed, 26 Sep 2012 06:19:53 -0700 (PDT)) it happened snipped-for-privacy@yahoo.com wrote in :

Never heard that expression, googling for it shows it can mean anything from Molotov cocktail to fire-extinguisher..

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I actually have 2 flashlights with indescandent bulbs, both run on 4 duracells, in once you can select between LEDs and indescandent. The duracells have been in once of those for more than 5 years I think. The other one had a sealed lead acid rechargable that I killed by accidently leaving that light on (I think), replaced it by 4 AA.

Na, ya, bit more light :-)

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Cydrome Leader 13 years ago

do they even make an 8 port eneloop charger anymore?

here's one, not sure where it was sold or why it's not available in the US

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I'd use the things if I could charge 8 at once in a charger that doesn't smell like burning chinese electronics and won't kill the batteries or burn the house down with some crazy speed charging mode.

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