25 Dec 05
Just wondered, obviously with a dvm you can make a good prediction
of the life left in a battery, like the AA cells for instance. Is it possible
to figure out the charge left if you had a sufficiently accurate
scale? Like Picograms or some such. Wouldn't a battery get a tiny
bit lighter as it used up charge? Hmm, its hermetically sealed mostly
but maybe gasses could escape. What do you all think?
27 Dec 05
1 edit
Originally posted by sonhousePractical application of knowledge is for the birds.
Just wondered, obviously with a dvm you can make a good prediction
of the life left in a battery, like the AA cells for instance. Is it possible
to figure out the charge left if you had a sufficiently accurate
scale? Like Picograms or some such. Wouldn't a battery get a tiny
bit lighter as it used up charge? Hmm, its hermetically sealed mostly
but maybe gasses could escape. What do you all think?
27 Dec 05
Originally posted by sonhouseAs far as I know most batteries (NiMH, NiCad, Li-Ion) aren't giving off gases as they are used. If this is true then conservation of matter states that the weight won't change as charge does.
Just wondered, obviously with a dvm you can make a good prediction
of the life left in a battery, like the AA cells for instance. Is it possible
to figure out the charge left if you had a sufficiently accurate
scale? Like Picograms or some such. Wouldn't a battery get a tiny
bit lighter as it used up charge? Hmm, its hermetically sealed mostly
but maybe gasses could escape. What do you all think?
27 Dec 05
Originally posted by XanthosNZDo electrons not "move out" of the battery? If so, a tiny loss of mass would occur?
As far as I know most batteries (NiMH, NiCad, Li-Ion) aren't giving off gases as they are used. If this is true then conservation of matter states that the weight won't change as charge does.
28 Dec 05
Originally posted by XanthosNZThats for sure! Maybe one or two strays would go in or out but I don't
They also 'move into' the battery at the same rate, conservation of charge and all that.
think we can weigh one electron yet. If there is energy used,
molecules will swap mass and mass is usually lost. If it isn't, THAT
is breaking the law of conservation of energy. Just like a fusion
reaction, some atoms whack together fiercely enough to fuse but
some of that energy is given off in various forms and the system
losses mass, even if say an electron is converted to a photon,
the mass goes down because the electron is now a photon which is
massless but the total energy will be conserved, ala E=MC^2.
28 Dec 05
Originally posted by sonhouseI could be wrong, but I don't think any mass is converted to energy in batteries. Energy is conserved because, for each unit of electrical energy produced, the battery loses a corresponding amount of chemical potential energy.
Thats for sure! Maybe one or two strays would go in or out but I don't
think we can weigh one electron yet. If there is energy used,
molecules will swap mass and mass is usually lost. If it isn't, THAT
is breaking the law of conservation of energy. Just like a fusion
reaction, some atoms whack together fiercely enough to fuse but
some of that energy ...[text shortened]... lectron is now a photon which is
massless but the total energy will be conserved, ala E=MC^2.
29 Dec 05
Originally posted by richjohnsonThis is correct.
I could be wrong, but I don't think any mass is converted to energy in batteries. Energy is conserved because, for each unit of electrical energy produced, the battery loses a corresponding amount of chemical potential energy.
A ball would gain a lot of energy if you took it to the top of a building. It doesn't lose mass though.
