Thought it would be fun to know how much weight the electrons actually add to the car. Is a fully charged MS measurably heavier than one running on empty? Thanks.

snapped from the net: Convert kilowatt hours to electron volts | energy conversion 1 kwh = 2.247x10^23 e/kwh Electron - Wikipedia, the free encyclopedia weigth of e = 9.109x10^-31 kg/e facts: Telsa charged with 85 kwh total weigth of charge then become 85 kwh * 2.3x10^25 e/kwh * 9.109x10^-31 kg/e = 1.740x10^-3 kg so generally speeking 1.7 g lighter when not charged comparet to a fully charged, but remeber a Tesla is never fully discharged so in practice it would "only" be around 1.5 gram

Thanks, guys! Love the math. My figuring as well was that it would be measured in grams. I think on a visceral as opposed to ethereal level, that is hard to fathom. I could imagine the glazed looks on most people faces trying to digest stuff like this in today's ICE world.

Fascinating stuff. And an ICE car with 17 (US) gallons on board would weigh an additional 103.24 Lbs, or 46829 grams.

That is all good and peachy but those electrons just move to the other side of the battery. You need to use E=MC^2 to determine the mass differential. We did it before I'll look for the link. or you can just put 85kWh into WolframAlpha 85kWh in g - Wolfram|Alpha Ends up being 0.000003405 grams! So not grams but mircograms.

maybe some point in futre your could fit the 85 kwh pack in a nut shell - or even load the car once in a lifetime in a larger pack and drive almost for ever. think about old fasion floppy discs (80 kb) and now you got a memory microSD card witch holds 64Gb data - back 20 years ago this was pure fantasy at same time size have shrinked a factor 100 - that is total a improvement of aprox 100.000.000 times. Im not saying its going to happen to battery storage, just saying it might happen at some point as demant of better battery are pressent and huge amount is invested into this field.

Actually the car doesn't get a net charge - there are no more electrons in the car after it is charged than before. It simply stores energy. If it was a supercapacitor this would be done via charge separation; a battery does something similar with chemistry. E=mc^2 applies. From Mass-energy equivalence - Wikipedia, the free encyclopedia one gram equals 25.0 million kilowatt hours. 85 / 25,000,000 = 3.4 micrograms. Edit: Darn El Sup beat me to it!

Like a wind-up toy with a spring, after the toy is wound up it weighs the same as before, except it has potential energy now that can be discharged. Of course, e=mc^2 applies (mass energy equivalence) so that stored energy has a very small weight as ElSupreme identifies.

your right - electron has not been filled, just moved. E = mc^2 m = E / c^2 1 [kwh] = 3.6x10^6 [J] c = 300.000.000 [m/s] 1 Tesla charge [Tesla*] = 85 [kwh] 1 [kg] = 1 [J] / (1 [m^2]/ 1 [s^2]) m [kg] = (85 [kwh/Tesla*] * 3.6x10^6 [J/kwh])/300.000.000 ^2 [m/s] m [kg] = 3.06x10^8 [J/Tesla*] / 9x10^16 [m^2/s^2] m [kg] = 0.34x10^-8 [J/Tesla*] / [m^2/s^2] m [kg] = 0.34x10^-8 [kg/Tesla*] m = 0.0034 [mg/Tesla*] 3.4 microgram

Actually, I'm just thinking that a battery may not be potential energy, it may be chemical energy. But the concept still applies.

Note that having a positive potential (charged) battery doesn't necessarily mean you added electrons. It just means that you added some electrons to one side and took away some from the other side of the barrier, causing a potential difference between the two. So aside from whatever asymmetries that exist in a LiON cell (how much there is, I don't know), there should be no difference in weight

I'm pretty impressed how many people on this board know enough science to answer this question correctly. Very different than the previous car club I was a part of! I'm really curious how people on other EV forums would do with this question. Is anyone willing to post a similar question on the Chevy Volt forum, the Nissan LEAF forum, the Fisker Karma forum, etc. and report the results? (you would obviously change the name of the EV to match the forum)

We could keep score based on how many responses before someone get the right answer. In our case, ElSupreme nailed it on the fifth response. Of course, this will only work if no one gives away the answer on the other forums