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Batteries ?

Psi Baba said:
I vote El Greco as the Forum's Most Patient Poster.
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You'd be wrong.
And I make no claim that this is the longest interval.


As for the actual topic...my cell phone lasts about a week on a charge, mainly due to the fact that no one ever calls me. I suggest E.G. collect data on usage before complaining.

Either that, or I could wear a speedo on a Greek island beach and see what it does to my calling plan.

...I will need to collect airfare donations for the latter...
 
There have been a lot of improvements, but I think cell phones is one area where you are not going to see the most improvement simply because it is very demanding product.

A good cell phone battery has low leakage current so that it can last a while in your glove box and still be ready when you need it. At the same time it has to jump up to a fairly high current for transmits. These two factors are generally a trade off. Technologies that reduce leakage current often also limit the amount of power available. Then you want high storage capacity. And lets through in a wide range of operational temperatures (the difference in simply leaving it in your car in winter or summer demands this). Then add in that you and me are going to handle the battery, which means it can't have special handling instructions.

I work on a mobile satellite communication product, that is supposed to have a lifetime of 5-years on a battery. We managed to get that, but as a trade-off our battery pack doesn't do well in the presence of moisture, so it wouldn't do well in cell-phone type app. The complany looked at a number of "bleeding-edge" solutions (super-caps being one) but had to settle on a "leading edge" solution.

Walt

P.S. add "bleeding-edge" to the annoying business speak thread.
 
Portable power solutions

El Greco,
I watched this video and was reminded of your recent inquiry. I think you’ll find MIT Professor, Donald Sadoway’s primer on portable power solutions interesting and charismatically delivered. Slow-start, but ramps up quickly from a 1/3rd of the way in. I give it an “A“ for the big picture. Would’ve been an A+ had it been delivered in a Speedo. Perhaps he wore one underneath? Enjoy!

same link as above--http://mitworld.mit.edu/stream/359/
 
Thanks Serenity. Haven't watched the video yet (don't have RP here) but I read the introduction:

But we have not yet arrived at the battery powered vehicle yet because the government has directed research elsewhere and because private money is more interested in batteries for laptops and cell phones. Sadoway is convinced: “If we put our money into battery research (the all-electric vehicle) would be here right now. This is a resource-limited problem
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Looks like I'm not too demanding after all; It's a government conspiracy that holds battery technology back :D
 
I am disappointed in these high capacity NiMh. When you go to pick up the camera every month of so for a couple of snaps, they are just about dead because they drain away internally. And there's no point having a couple of spares in the case, they'll be flat too.
 
I heard about a new battery paper on BBC a while back, the battery parts are consolidated into a paper form. Would take a batter the size of an unfolded newspaper to power a car, and they can't make them bigger than a few inches yet.
 
Silly Green Monkey said:
I heard about a new battery paper on BBC a while back, the battery parts are consolidated into a paper form. Would take a batter the size of an unfolded newspaper to power a car, and they can't make them bigger than a few inches yet.
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But doesn't the word "battery" actually mean several cells working together?
Why couldn't they connect several little ones together? I doubt that electric
cars would be the best application area for this. They'd no doubt use it in
other areas; e-paper, medical thingys, internet enabled toilet rolls etc.
 
El Greco said:
I see significant advances in miniaturization, yet the energy to weight ratio for batteries doesn't seem to have improved much during the last 10 years or so. Why is that ?
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Why would you expect such advances? There have been virtually no advances in the energy density of fossil fuels over the last half century, and that's a closer problem to batteries than miniaturization of electronics.
 
Correct me if I'm wrong, but doesn't a Lithium ion polymer, or whatever the bleeding edge is, rechargable battery have far better energy density than the best ultracapacitor? Granted, the ultracapacitor has a far better power density, but in terms of storage, the battery is still far better.

What I think would make the biggest difference in cell phone life is a new cell phone that's just a phone, and which lacks a large LCD screen (and if possible the small, blurry camera that seems so in vogue now) that's tied to batteries with a very slow self-discharge rate.

And, as a slightly off-the-wall idea, a special holster for the cell phone that fits directly to the wearer's skin, and has thermocouples that recharge the cell phone while it sits in the holster using the wearer's body heat.
 
I don't know why El Greco does have a size problem.

The battery of my first cell phone was roughly the size of a pack of cigarettes, and you had to charge this baby every night.

The battery of my second cellphone was the size of a remote control.

My current phone's battery is 3 x 4 centimeters and maybe 3 milimeters thick. That's around one third the dimensions of a credit card and thick like three stacked coins. I charge it once a week.

I'd say that's quite some improvement.
 
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A guy I know gave me a good tip to maximize battery life. He said he always stored his batteries in the freezer to ensure freshness!:boggled:
 
The idea of freezing batteries is to slow down the chemical reactions that lead to self discharge. How well it works depends on the battery chemistry and construction. The concept started with the old carbon batteries that I don't think you can get anymore. Freezing doesn't help alkaline batteries much because they already have a long shelf life. Nicads would self discharge quite rapidly so cooling them has a significant effect. With newer battery technologies, I would look for research to see if cold storage is effective and to make sure it won't destroy the battery.
 
wahrheit said:
My current phone's battery is 3 x 4 centimeters and maybe 3 milimeters thick. That's around one third the dimensions of a credit card and thick like three stacked coins. I charge it once a week.
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Once a week???? What phone do you have ?

And, most important, do you ever use it ? :D
 
El Greco said:
Once a week???? What phone do you have ?

And, most important, do you ever use it ? :D
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Cheapo Sony Ericsson, forgot the model number, nice display, mp3, video and 2MP camera. Average stuff I'd say.

I'm not using it around the clock though, I'm more of a landline guy. :)
 
Batteries are a challenging technology. Unfortunately, the energy that can be safely stored in a reversible chemical reaction is limited. As already pointed out, they have to work over a range of environmental conditions. And they have to be manufactured with very fine tolerances to get maximum power in minimal space without blowing up. Still there have been huge advances over the old Ni-Cad batteries.

But much of the extended battery life in PCs and cell phones have come from power saving designs in the electronics. Laptop PCs have special low voltage chipsets and power saving modes. Cell phones operate at much lower power today than the first generation phones (and cell towers are far more mumerous).

Expect advances to continue on both fronts: improved energy density in batteries and reduced energy consumption from devices.

The methanol powered fuel cell is a great idea, but still a long way from commercialization. The catalysts are very expensive, manufacturing sufficient energy density requires extreme tolerances, and there are concerns about the safety of methanol.

I don't buy the CT bull that battery powered cars would be a reality if only the government and oil companies weren't sabotageing the research. There is a huge market for reliable, high energy density batteries, and a great deal of research effort has been expended on the problem. It is an extremely difficult challenge, and improvements come slowly.
 
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