Battery Technology

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sandorszabo
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Battery Technology

I'd like to learn more about the electro-chemical properties of batteries. For example, I wonder why high-drain events like (jackrabbit starting) are detrimental to battery life. So I navigated to the "Community Handbook" section of this site and discovered that all the handbooks are still posted to the old .net site.

Any suggestions where to start to learn about technical/scientific aspects of battery use/technology?

Efried
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Re: Battery Technology

Hi,

chemical processes are needed to produce the energy and they need time. If you go wild with amps the battery heats up.
You might think about Supercaps (VINA, WEMA...) if you have the money. If you find some costing less than 10 cent per Farad please tell us. The Vina 220F supercapacitors I have tested here www.hyperbike.cc

sandorszabo
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Re: Battery Technology

So...since high-capacitance devices would seem to be a natural complement to an eV circuit, their apparent absence from the market is due primarily to cost?

LinkOfHyrule
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Re: Battery Technology

Pretty much. Figure you pay abou $1.30 for one watt hour for lithium. I worked out what I paid for a little supercap and I came up with over $400.00 a watt hour!

That and size. The don't even come close to lead-acid in terms of energy density as far as I know.

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

reikiman
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Re: Battery Technology

I worked out what I paid for a little supercap and I came up with over $400.00 a watt hour!

Hmm, interesting.

The don't even come close to lead-acid in terms of energy density as far as I know.

I believe that's inaccurate. What I'd read long ago is that ultracapacitors (a.k.a. supercapacitors) have power density far above even lithium batteries. Oh.. but there's two kinds of densities. One is kilowatt-hours per kilogram, the other rates it per liter of volume. It's possible I was reading power density by weight, and that power density by the size of the pack would be very bad. Dunno..

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spinningmagnets
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Re: Battery Technology

I recall reading a while back somewhere (notice how I'm purposefully vague, so I can't be challenged?) one of the possible options being discussed for Hybrid vehicles was adding ultracaps, or at the very least adding a socket so ultracaps could be easily added if appropriate for a given customer use profile.

The way I remember it, the main benefit was being able to capture a significantly larger amount of re-gen when slowing or going downhill. Apparently batteries prefer to discharge/re-charge slowly, and hybrid cars produce more re-gen watts than the chemical battery could swallow.

Also, Ultra-caps are better for the first few seconds of a standing start, but I'm sure it would require a very sophisticated (and more expensive) controller.

Definitely a benefit, but you know corporations...will the customers pay more for this particular feature? Customers sometimes request one thing on a survey, but stay away when its time to put down a cash deposit. Remember 4-wheel steering for cars?

I seem to remember that ultracaps are used as car starter batteries in Canada and Russia due to extreme cold. I'm guessing its more expensive, and requires a computerized controller. I recall a friend in Alaska using and electric engine heater with an electric battery blanket on an extension cord and timer, even though it was indoors.

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LinkOfHyrule
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Re: Battery Technology

reikiman: Not really. Any of the comercially available supercaps have a pathetic energy density by both weight and size, ranging from about 0.5 to 10Wh/kg. I believe you are thinking of the claimed energy density of the EEstor modules, which supposedly are about twice as energy dense per kg as lithium chemistries.

spinningmagnets: You're right. Capacitors are much more efficient at absorbing a charge than batteries. Typically, they are more than 90% efficient at storing a charge and are, except for their internal resistance, unaffected by how fast they are charged or discharged. They are also unaffected by temperature (actually, it may be beneficial to run them at supercold temperatures, as that would lower their internal resistance).
You are also right in assuming that they need a way to regulate thier voltage. Since a capacitors discharge curve is linear, the voltage across it's terminals is direcly proportional to the energy remaining the the capacitor. You basically need something along the lines of a switching power supply. However, attaching some sort of voltage regulator allows it to function as a regular battery. You would not need a specialized controller to run a vehicle.

I'm surprised almost no one mentions this advantage: Supercapacitors need no specialized charger. All you have to do is plug them into a voltage source, and they will charge until they match that voltage source. In addition, as long as you don't charge/discharge it so fast that the internal resistance of the capacitor does not create too much heat, you can charge or discharge it as fast as you want without affecting the cycle life. On top of that, considering that they do not undergo any chemical or physical change when you charge them, their cycle life is ridiculously high, on the order of hundreds of thousands of cycles.

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

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