Lithium AA's

[Phaserburn]

Lithium AA\'s

Much has been discussed about the slightly higher voltage and capacity of these cells, especially as relates to single AA lights like the Ultra. But don't these cells also have a much flatter discharge rate? Where is there information on that, on how a lithium AA performs vs. a alkaline?

 

[milkyspit]

Re: Lithium AA\'s

Hey Phaser, /ubbthreads/images/graemlins/wink2.gif

Yessir, they do! Although I think these AA lithiums are a little different animal from the 123 cells, sort of like distant cousins rather than brothers.

The AA lithium cells, like their 123 cell cousins, are lightweight, carry lots of energy capacity relative to their weight, are more capable of driving higher current loads than alkalines, and discharge flatter than alkalines.

But based on personal observation, I'm coming to the conclusion that AA lithiums share some characteristics with AA alkalines that the 123 cells don't so much share. For instance, a 123 cell's unloaded voltage stays in a pretty tight range during its entire service life, starting at mayve 3.2V and ending around 2.8V. Lithium AA cells, on the other hand, begin life with something around a 1.7V unloaded voltage, but that voltage seems to decline steadily with use, just like alkalines do. This means an AA lithium can be checked on a voltmeter to get a good guess as to its condition, whereas it's better to check a 123 cell for flash amps to assess its condition.

Take a look at the Energizer website, under the "Technical Info" link in the page header. There's a datasheet for the lithium AA cells over here that gives you lots of performance data.

 

[Phaserburn]

Re: Lithium AA\'s

Thanks, Milky! /ubbthreads/images/graemlins/wink2.gif

 

[SilverFox]

Re: Lithium AA\'s

Hello Scott,

I think you better take another look at the data sheet you linked to. I would say that the lithium AA's are very similar in performance to the 123's.

123's start out at 3.2 v and end up at 2.8 v. 2.8 v is 87.5% of the original.

L91's start out at 1.6 v and end up at 1.4 v. 1.4 v is also 87.5% of the original.

Looking at the voltage discharge curve at the bottom of the page, it looks pretty flat to me.

Tom

 

[_mike_]

Re: Lithium AA\'s

What would be a better choice for cordless keyboard and mouse ....... AA Lithium's or Alkaline's? Logitech recommends alkaline's, but I was wondering what you guys thought.

Thanks,
Mike

 

[milkyspit]

Re: Lithium AA\'s

Mike, that's an interesting question. I'll just talk some techno mumbo jumbo and dodge the answer, okay? /ubbthreads/images/graemlins/tongue.gif No, seriously, it's tough to say. The basic concept is that alkaline cells work well with relatively low current flow, such as 25mA. If the keyboard and mouse draw low current from the batteries, you'd be wasting your money on the lithiums, as alkalines would do just as well as a drastically lower price. If, on the other hand, the keyboard and mouse suck down lots of current, like hundreds of milliamps, the lithium would really show its value by lasting much longer than the alkaline. You could always try a couple of each and keep track of how long they last! The $5 or so invested would give you all the information you'd need to make a wise choice for the long term.

SilverFox, I'll stand by what I stated about the cells. But I will say that it's just my personal experience, and I'm making no premise of stating objective fact. Further, I'll admit that I tested in a pretty extreme environment, using a single lithium AA to drive a MM+ wide open sandwich. That usage is pulling a ton of current from the battery! And when a lithium AA is pushed to the edge like that, my experience is that it does indeed start to behave more like an AA alkaline than a 123 cell. If you look at the digital camera graph at the bottom right of the last page in the data sheet, you'll see the lithium AA begin life at 1.6V, then slope fairly steadily downward toward 1.2V, then really fall off a cliff from there, going from 1.2V all the way down to 0.8V in the last 5-10 minutes.

Meanwhile, I've taken 123 cells that can't light even an Arc LSL flashlight, measured the unloaded voltage and still found 2.8V. That's all I was getting at. The 123 cell seems to lose its capacity for current flow, while the lithium AA cell seems to lose its capacity for maintaining voltage, even when unloaded.

But your mileage may vary!

 

[paulr]

Re: Lithium AA\'s

Mike, the Logitech cordless mouse that I've used burns through alkalines like candy, one or two pairs a week with heavy use. Lithiums would last longer but cost a fortune. The answer is rechargeables.

 

[milkyspit]

Re: Lithium AA\'s

Spoken like a man who's been there. Paulr, that sounds like good advice.

 

[jhereg]

Re: Lithium AA\'s

That Logitech corless mouse sounds like it has a problem to me. My experience is they should last at least a month or two with relatively heavy use. The older mice with a ball instead of a LED seemed to last several times as long. I have to replace the batteries in the Logitech cordless mouse here about once every 4 or 5 months. (That battery life is consistent with the answers from other techs I know.)

Andy

 

[FlameOn]

Re: Lithium AA\'s

I use rechargeable AAs in my keyboard, mouse and remotes and I get longer run time than with standard AAs....I had them in my keyboard and mouse for over two months and were still going when I swithced them out...and I feel better about the environment not throwing them out...got a pack of 12 AA and 12 AAAs from battery station for 19.95.....

 

[SilverFox]

Re: Lithium AA\'s

Hello Scott,

I trust your real world experience.

I was just pointing out that from the data sheets, the graphs for both battery types (at 1000 mA constant drain) had very similar curves. The fact that the L91 graph looks flatter I believe is because the Duracell 123 graph is plotted on a log time scale.

Compare L91 with 123

Tom