Batteries and Capicitors
08-19-2003, 09:20 AM
#1
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Yeah, I know stuff like this has been posted a tonne on here, but I have a question from a different angle.
What is the difference between a Battery and a capicitor? Both can receive and hold a charge, both can be discharged/drained of juice; both give out varying amounts of current as demanded.
What makes them different?
I think (but don't know) that caps can hold any amount of voltage while batteries must deal with a specific pre-determined voltage (car batts 12v; aa 1.5v; etc)
And I know that the internal make up of each is different.
Can a car Battery be replaced by a Cap? Say 3-4 farad? Why or why not?
I know that all batteries have a finite life, and I am fairly sure so do Caps - but typically which have a longer life under the same circumstances?
Thanks
What is the difference between a Battery and a capicitor? Both can receive and hold a charge, both can be discharged/drained of juice; both give out varying amounts of current as demanded.
What makes them different?
I think (but don't know) that caps can hold any amount of voltage while batteries must deal with a specific pre-determined voltage (car batts 12v; aa 1.5v; etc)
And I know that the internal make up of each is different.
Can a car Battery be replaced by a Cap? Say 3-4 farad? Why or why not?
I know that all batteries have a finite life, and I am fairly sure so do Caps - but typically which have a longer life under the same circumstances?
Thanks
08-19-2003, 09:36 AM
#2
A fully charged 4 farad cap can supply juice for maybe 2 seconds. 
Good luck with that.
This question must have been a joke, but regardless; if you needed to know, that's alright.
The way a cap is made, it is designed to put out the juice FAST, faster than most conventional batts can do; and dispense its energy quickly. That's why they're used to keep a clean bass/music signal.
I've heard bass notes in a car that needed a cap badly. Bass was nearly non-existent for the first second of the note, the battery simply couldn't keep up with the demand of the amp.
Good luck with that.
This question must have been a joke, but regardless; if you needed to know, that's alright.
The way a cap is made, it is designed to put out the juice FAST, faster than most conventional batts can do; and dispense its energy quickly. That's why they're used to keep a clean bass/music signal.
I've heard bass notes in a car that needed a cap badly. Bass was nearly non-existent for the first second of the note, the battery simply couldn't keep up with the demand of the amp.
08-19-2003, 12:26 PM
#4
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A battery works by chemical reaction. It is the chemical reaction that produces the electical potential. So far, in a practical battery, the potential across any one cell is 1.5v so any battery of greater voltage is just cells wired in series ie. a 12volt battery has 8 cells in it. For greater current out of each cell, it just gets made larger eg. a D cell compared to a AAA cell.
The side effect of that chemical reaction is the consumption of the internal components. This is why batteries eventually fail.
A capacitor works by polarizing the plates within it. There are two plates separated by a dielectric. For this reason you can apply and drain a charge from a cap but the cap does not 'make' energy. As long as the dielectric does not break down and the plates are not damaged by extreme use a capacitor will never be consumed.
Try www.askjeeves.com for decent battery info. http://web.ask.com/redir?bpg=http%3a%2f%2fweb.ask.com%2fweb%3fq%3dbat tery%26o%3d0%26page%3d1&q=battery&u=http%3a%2f%2ft m.wc.ask.com%2fr%3ft%3dan%26s%3da%26uid%3d0E6D5E98 842A724F3%2 6sid%3d167EBE98842A724F3%26qid%3dCCBB28DCC20D2B41A 1333A54E38B2F38%26io%3d0%26sv%3dza5cb0db1%26ask%3d battery%26uip%3d18cf07e3%26en%3dkb%26eo%3d0%26pt%3 dHow%2bdoes%2ba%2bbattery%2bwo rk%253f%26ac%3d0%26qs%3d0%26pg%3d1%26ep%3d1%26kb_s n%3dJeeves%26kb_lhs%3d26003%26kb_lhx%3dHow%2bdoes% 2ba%2bbattery%2bwork%253f%26kb_ad%3d19%26kb_f%3d%2 6kb_lid%3d%26kb_iid%3d%26kb_li t%3da%2bbattery%26kb_stp%3d0%26u%3dhttp%3a%2f%2fww w.howstuffworks.com%2fbattery.htm&s=a&bu=http%3a%2 f%2fwww.howstuffworks.com%2fbattery.htm
Yes you can replace a battery for starting with a capacitor. You just need one that will sustain the starter's draw for 3 seconds or so. About 6 years ago a company was going to market a 60Farad cap and they bragged it could start a car easily.
[ August 19, 2003, 01:27 PM: Message edited by: Dukk ]
The side effect of that chemical reaction is the consumption of the internal components. This is why batteries eventually fail.
A capacitor works by polarizing the plates within it. There are two plates separated by a dielectric. For this reason you can apply and drain a charge from a cap but the cap does not 'make' energy. As long as the dielectric does not break down and the plates are not damaged by extreme use a capacitor will never be consumed.
Try www.askjeeves.com for decent battery info. http://web.ask.com/redir?bpg=http%3a%2f%2fweb.ask.com%2fweb%3fq%3dbat tery%26o%3d0%26page%3d1&q=battery&u=http%3a%2f%2ft m.wc.ask.com%2fr%3ft%3dan%26s%3da%26uid%3d0E6D5E98 842A724F3%2 6sid%3d167EBE98842A724F3%26qid%3dCCBB28DCC20D2B41A 1333A54E38B2F38%26io%3d0%26sv%3dza5cb0db1%26ask%3d battery%26uip%3d18cf07e3%26en%3dkb%26eo%3d0%26pt%3 dHow%2bdoes%2ba%2bbattery%2bwo rk%253f%26ac%3d0%26qs%3d0%26pg%3d1%26ep%3d1%26kb_s n%3dJeeves%26kb_lhs%3d26003%26kb_lhx%3dHow%2bdoes% 2ba%2bbattery%2bwork%253f%26kb_ad%3d19%26kb_f%3d%2 6kb_lid%3d%26kb_iid%3d%26kb_li t%3da%2bbattery%26kb_stp%3d0%26u%3dhttp%3a%2f%2fww w.howstuffworks.com%2fbattery.htm&s=a&bu=http%3a%2 f%2fwww.howstuffworks.com%2fbattery.htm
Yes you can replace a battery for starting with a capacitor. You just need one that will sustain the starter's draw for 3 seconds or so. About 6 years ago a company was going to market a 60Farad cap and they bragged it could start a car easily.
[ August 19, 2003, 01:27 PM: Message edited by: Dukk ]
08-19-2003, 01:36 PM
#5
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Originally posted by Chadxton:
. . . This question must have been a joke, but regardless; if you needed to know, that's alright . . .
. . . This question must have been a joke, but regardless; if you needed to know, that's alright . . .
I simply didn't know the difference between the two types of storage.
Do I understand this right? - Caps can supply a huge amount of current, but not for a long period. Batteries, while they have quite a limited supply of current, can give supply that current for a much longer period of time. The impression that I go from Dukk is that batteries "make" electricity from the potential energy that is found in the chemicals, while caps simply store what has already been produced . . .
Am I getting this?
I'll click around on those sites Dukk see if I can figure out more.
08-19-2003, 02:43 PM
#7
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A 1Farad capacitor stores 1Farad worth of electricity. It will dump that potential instantly if you short it with a screwdriver or something or it can last quite a while running, say, a flashing LED.
What you would need to do if you wanted to start your car is figure out how many amps of draw the alternator takes, you know it is 12volts or so, and figure an average time needed running the starter before the car starts and say maybe 25-50% extra for reserve. Then you can figure the total power needed to start the car and how many farads of reserve you would need.
RC likes to go on and on how a 9volt transistor battery has something like 10x plus the energy capacity of a 1 Farad capacitor. Unfortunately it is at too low a voltage and cannot be tapped quickly enough to be useful.
What you would need to do if you wanted to start your car is figure out how many amps of draw the alternator takes, you know it is 12volts or so, and figure an average time needed running the starter before the car starts and say maybe 25-50% extra for reserve. Then you can figure the total power needed to start the car and how many farads of reserve you would need.
RC likes to go on and on how a 9volt transistor battery has something like 10x plus the energy capacity of a 1 Farad capacitor. Unfortunately it is at too low a voltage and cannot be tapped quickly enough to be useful.
08-19-2003, 07:35 PM
#8
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Join Date: Aug 2003
Posts: 348
Batteries here , Capped asses there ...
If you don't have the right source aka Alternator , both become somewhat obsolete . Mainstream systems however , can get away in some european and american cars ( trucks ), hell maybe even a Japanese Lexus or Acura or Nissan etc ... , ohh wait , where are they made nyway ??? [img]smile.gif[/img] Raw sushi but no raw electrical power ..... little generalizing but true for many cases .
Nyways , for unfortunate people like myself on my previous ride , a Civic , and about 1500 rms n change , a Stinger Alternator was a must , cosidering I did not go mono on the sub amp .
Long story short , never installed changed to VW with 90 amps , ( need to sell the old new Honda alternator from Stinger 160 amp listed in 4 sale by the way ) and get a refurb'd or junked Bosch 120 amp bare min .. The system has about 16 farads of cap and secondary small battery aka BatCap . Proally uselss but claims to have hundreds of farads ..
The tiny point I am tryin to make is as following .
Should you requier some serious juice to your system , consider alternators first unless you really can get away with a cap . A battery and cap are a must addition regardless , as power can not go without storage and dispensing it when needed . Like long term and short term Battery is to Cap is the children of Alternator .
Cheeers .
[ August 19, 2003, 08:43 PM: Message edited by: Lil_Odessa ]
If you don't have the right source aka Alternator , both become somewhat obsolete . Mainstream systems however , can get away in some european and american cars ( trucks ), hell maybe even a Japanese Lexus or Acura or Nissan etc ... , ohh wait , where are they made nyway ??? [img]smile.gif[/img] Raw sushi but no raw electrical power ..... little generalizing but true for many cases .
Nyways , for unfortunate people like myself on my previous ride , a Civic , and about 1500 rms n change , a Stinger Alternator was a must , cosidering I did not go mono on the sub amp .
Long story short , never installed changed to VW with 90 amps , ( need to sell the old new Honda alternator from Stinger 160 amp listed in 4 sale by the way ) and get a refurb'd or junked Bosch 120 amp bare min .. The system has about 16 farads of cap and secondary small battery aka BatCap . Proally uselss but claims to have hundreds of farads ..
The tiny point I am tryin to make is as following .
Should you requier some serious juice to your system , consider alternators first unless you really can get away with a cap . A battery and cap are a must addition regardless , as power can not go without storage and dispensing it when needed . Like long term and short term Battery is to Cap is the children of Alternator .
Cheeers .
[ August 19, 2003, 08:43 PM: Message edited by: Lil_Odessa ]
08-19-2003, 07:49 PM
#9
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This thought did not originate from car audio.
With this whole black-out thing, the news ran a few segments about families that live "off-grid." I think living off-grid is a cool idea, but you need to store the energy somewhere. And in my mind, I wouldn't want to replace batteries every 10 years or so. I was wondering if there was a way to store energy, that has an infinite life.
Also, batteries are DC; wall outlets are AC that means a transformer is required and with the addition of a transformer, more energy is lost in the transformation. - that is what originally prompted the capacitor idea in my mind.
Being self-sufficient is a cool idea. Some day I would hope to be that way - yah, I guess I'm a bit of a hippie. I'm just looking to learn more about the possibilities.
[ August 19, 2003, 08:50 PM: Message edited by: maltesechicken ]
With this whole black-out thing, the news ran a few segments about families that live "off-grid." I think living off-grid is a cool idea, but you need to store the energy somewhere. And in my mind, I wouldn't want to replace batteries every 10 years or so. I was wondering if there was a way to store energy, that has an infinite life.
Also, batteries are DC; wall outlets are AC that means a transformer is required and with the addition of a transformer, more energy is lost in the transformation. - that is what originally prompted the capacitor idea in my mind.
Being self-sufficient is a cool idea. Some day I would hope to be that way - yah, I guess I'm a bit of a hippie. I'm just looking to learn more about the possibilities.
[ August 19, 2003, 08:50 PM: Message edited by: maltesechicken ]
08-20-2003, 12:46 PM
#10
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^ Take two BIG water tanks and put one up a hill a couple hundred feet above the other.
During the day you use solar energy to run a pump that pumps the water from the low tank to the high tank. At night you allow the water to gravity feed back into the low tank through a turbine to generate electricity
What battery? [img]tongue.gif[/img]
During the day you use solar energy to run a pump that pumps the water from the low tank to the high tank. At night you allow the water to gravity feed back into the low tank through a turbine to generate electricity
What battery? [img]tongue.gif[/img]
