henry@utzoo.uucp (Henry Spencer) (11/13/88)
In article <1638@adec23.UUCP> mark@adec23.UUCP (Mark Salyzyn) writes: >Does any one know the capacitance of a 60Ah battery, or is it not possible >to measure it ?!:-) It's certainly measurable -- a battery is essentially a large, polarized, highly non-linear capacitor -- but it depends on the voltage, which you didn't specify. 60 Ah is 60*3600 coulombs of charge; capacitance is charge/voltage. If we assume a car battery (12V), that's an 18 kF capacitor. (Just to head it off... Anyone who wants to argue about whether a battery is a capacitor should know that this was hashed out a couple of years ago. The obvious difference is the non-linearity of the battery, but many capacitors are detectably non-linear too. Nonlinearity is normally felt to be a feature in batteries and a bug in capacitors, which is why the difference in degree.) -- Sendmail is a bug, | Henry Spencer at U of Toronto Zoology not a feature. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
feg@clyde.ATT.COM (Forrest Gehrke) (11/14/88)
In article <1988Nov13.001657.21990@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: > In article <1638@adec23.UUCP> mark@adec23.UUCP (Mark Salyzyn) writes: > >Does any one know the capacitance of a 60Ah battery, or is it not possible > >to measure it ?!:-) > charge/voltage. If we assume a car battery (12V), that's an 18 kF capacitor. > > (Just to head it off... Anyone who wants to argue about whether a battery > is a capacitor should know that this was hashed out a couple of years ago. > The obvious difference is the non-linearity of the battery, but many > capacitors are detectably non-linear too. Nonlinearity is normally felt > to be a feature in batteries and a bug in capacitors, which is why the > difference in degree.) Why should anyone want to gainsay you, Henry? One has only to look at the output waveform of the rectified output of the alternator with and without connection to the battery to be convinced that a large capacitor is involved. Forrest Gehrke k2bt