do batteries weigh less when they are exhausted than when they are fully charged?

Answer 1

I think that the answer must be YES.

Let's assume that these are dry cell batteries (so they are not losing any matter by evaoporation or gaining any by using oxygen in the atmosphere.

So no particles get in or out of the battery. However, the battery, once spent, has lost some energy (perhaps by powering a torch which then gives out light and heat energy).

According to Einstein's famous equation, E=mc^2. So this amount of energy must be equivalent to (an extremely small) quantity of matter and the mass of the battery must have reduced by this amount. It will not be measurable in ordinary circumstances and I am sure that other factors (eg dust particles settling on it, etc) would FAR outweigh this mass of the released energy. But theoretically, yes, it would weigh less.

One gets a similar kind of balance in radioactive decay; a uranium nucleus decays into some other bits and pieces but the mass of the other bits and pieces is slightly less than the mass of the original uranium nucleus in order to account for the energy that is released (in the form of EM radiation).

Hope this makes sense.

Answer 2

A battery works via emitting an electron at one end, (it does artwork by a circuit) and receiving it on the different end. This motives a chemical reaction, however an identical form of electron, protons, and neutrons remains interior the battery after it is lifeless. So it does not exchange mass. different than - that as quickly as an merchandise losses potential (subsequently, the chemical factors which exist after the battery is discharged are at a decrease potential state than while charged) They loss mass in accordance to Einstein's E=mc^2 - yet this modification in mass is somewhat small. as an occasion, as a coarse estimate assume a typical 9V battery can run a 100W radio for 10 hrs. the quantity of potential mandatory for it extremely is one hundred Nm/s *10*3600 s = 360000s the fee of light is 3x10^8 m/s subsequently plugging interior the numbers... the mass loss could be 4 x 10^-12 kg (or 0.000004 mg )

Answer 3

Perspykashus is right.
In fact any chemical reaction that evolves energy (heat, electricity, light, etc) results in a mass defect - the mass of the reactants after the reaction is less than that before.

However for practically all reactions that are less energetic than nuclear fission or fusion, the change in mass is not detectable by ordinary measurements.

In the case of batteries, high-capacity NiMH batteries are rated at about 150 Wh/kg (http://en.wikipedia.org/wiki/Lithium-ion_battery)
So the difference in mass between a 1 kg fully charged and discharged battery is 150 Wh = 5.4 E5 J. By Einstein's mass/energy equivalency formula this is 6 E-12 kg. You would have to have to make a measurement sensitive to a few parts in a trillion in order to detect it. That's difficult to do!

Answer 4

In all sealed batteries there is no discernable loss in mass. In some car batteries there is a loss of water (you sometimes have to 'top up' the battery with distilled water) but this is mostly due to the charging up of the battery or simple evaporation rather than any substances lost when the battery is discharged.

Answer 5

Yes they do weigh less.
In this type of chemical reaction, battery energy is released and converted to other forms of energy for whatever application it was used for.
Energy released mean less mass remained.

Answer 6

Its just a chemical reaction. Nothing is lost in the process so no they wont.

Answer 7

are we talking vehicle batteries or reg. double A batteries???

Answer 8

no, they weigh the same...elec. current has no weight value.

Answer 9

sorry ele doesn't have any weight to it

Answer 10

no ? silly isint it ,