There is no power (energy) until there is current (amps). ------------------------------ And there is no power until there is voltage. It is expressed as the product of quantity of electrons (current) and the electromotive force producing the current (voltage). But when you say the first unit of charge in a battery is the same as the last and the voltage makes no difference then you are saying P= doesn't matter x I. I don't think so and neither does the power company. 100 amps at 12 volts costs less than 100 amps at 14 volts for the same unit of time.
Kirk -----Original Message----- From: Darryl McMahon [mailto:[EMAIL PROTECTED] Sent: Thursday, May 01, 2003 5:57 PM To: biofuel@yahoogroups.com Subject: Voltage (was: RE: [biofuel] World's first hydrogen service station opens in Iceland) Sorry to quibble, but voltage is potential difference, which implies a capacity to do work but it is not energy. When current is flowing (amps), work is being done, and that is energy. Volts x amps = watts. Energy is measured in watts, not volts. So, let's consider the power equation, P=EI, where P = power (in watts), E = voltage (in volts), and I = current (in amps) Power (energy) is measured in watts, but E is potential difference (or electromotive force) and is measured in volts. There is no power (energy) until there is current (amps). Voltage is not energy, and that is what P=EI says. Voltage x current = energy. Darryl McMahon "kirk" <[EMAIL PROTECTED]> wrote: > but voltage is not energy > ------------------ > P=EI > > That says it is. > > Kirk > > -----Original Message----- > From: Darryl McMahon [mailto:[EMAIL PROTECTED] > Sent: Thursday, May 01, 2003 3:38 PM > To: biofuel@yahoogroups.com > Subject: Re: [biofuel] World's first hydrogen service station opens in > Iceland > > > When charging a deep-cycle battery, it does not take any more energy (in > watt- hours) to put in the tenth kilowatt-hour than it did to put in the > first kilowatt- hour (assuming at capacity somewhat larger than 10 kWh). > It may take a higher voltage (potential difference) to continue the > charging as the battery becomes charged, but voltage is not energy. > > (There is an exception at end of charge for certain chemistries, where > more energy is used to put in the last few percent of the full charge, but > this is no longer charging, but overcharging, sometimes referred to as > equalization. A smart charger reduces charging current accordingly in > this situation.) > > When you are putting a gas into a pressurized vessel, it does take higher > pressure to overcome the rising pressure in the vessel. It is the work > required to create the higher pressure that takes more energy. > > Darryl McMahon > > Icarus Solem <[EMAIL PROTECTED]> wrote: > > > Hello, > > > > It seems that the same is true for charging a battery system, only in > > this case you are working against the electric potential of the battery > > cell, instead of the mechanical potential of the pressurized system. If > > a hydrogen tank is initially empty, it takes more energy per unit to > > fill it as the pressure rises. The same is true for a deep-cycle > > battery system - as you run the electrochemical reation to charge the > > battery, you have to input more energy to run the reaction uphill? I'm > > guessing that these efficiencies can all be improved - just as the > > efficiency of biomass to ethanol conversion has increased over the > > years. > > > > Cheers, Karus > > > > On Wed, 30 Apr 2003, martin wrote: > > > > > An electrochemical reaction where the desired product has to be forced > > > out at a relatively high pressure requires more energy to push the > > > reaction over equilibrium. > > > > > > kirk wrote: > > > > > > >I'm not aware of any change in potential with pressure. You have any > > > data to > > > >the contrary? > > > >Kirk > > > > > > > >-----Original Message----- > > > >From: martin [mailto:[EMAIL PROTECTED] > > > >Sent: Tuesday, April 29, 2003 9:29 PM > > > >To: biofuel@yahoogroups.com > > > >Subject: Re: [biofuel] World's first hydrogen service station opens > > > >in Iceland > > > > > > > > > > > >Down goes efficiency. > > > > > > > >kirk wrote: > > > > > > > > > > > > > > > > > > > > > -- > > > --- > > > Martin Klingensmith > > > http://nnytech.net/ > > > http://infoarchive.net/ > Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.474 / Virus Database: 272 - Release Date: 4/18/2003 ------------------------ Yahoo! Groups Sponsor ---------------------~--> Make Money Online Auctions! Make $500.00 or We Will Give You Thirty Dollars for Trying! http://us.click.yahoo.com/KXUxcA/fNtFAA/uetFAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
