Tesla Motors Club

I realize this is a somewhat non-sensical question, but I am trying to vaguely find the "weight" of 85kWh of electrons. "It takes 6 x 10^18 electrons to equal a coulomb. A kilowatt hour is a measure of power. An amp is equal to one coulomb/second. A watt is volts x amps. SO, if you had a specific voltage, you could figure amps & watts, and from there how many electrons. "
As an example ""
120V, a kilowatt hour is an 8.33 amp device running for an hour
8.33 amps/sec = 8.33 coulombs/sec
8.33 x 60 x 60 = 29,998 coulombs/hour
29,998 x 6 x 10^18 = 1.8 x 10^23 electrons. Hmm, not even a mole? Sounds low, but I believe the maths right.
An electron's mass is 9.11×10−31 kg
9.11 x 10^-31 x 1.8 x 10^23 = 1.64 x 10^-7 kg or .16 micrograms ""

However, I don't know the amps and volts the Tesla battery runs at and physics class was 40 years ago.
I am also uncertain if the weight of the electrons "vanishes" as they are "used" or just move around but doubt that.
('gallons of sunshine' do have "weight/mass" since they will push a solar sail but this is not exactly related to the question)
The question is in realtion to someone posting that 6 gallons of gasoline weigh far less than an 85kWh battery and I am trying to point out they are not the same, the electrons are the fuel as is the gasoline,
thanks for bearing with me