The full battery will weigh more so keep that in mind. Ideally charge is 20% for those runs.
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Does a full battery weigh more?
- Thread starter SION1771
- Start date
The full battery will weigh more so keep that in mind. Ideally charge is 20% for those runs.
shanejackson
Member
Please tell me you are joking....
Msjulie
Active Member
well maybe it's a super sensitive scale! 
"This effect will make a charged battery ever so slightly heavier than a discharged battery because it has more energy. But the change is very small. Other types of batteries will absorb or release gasses during charge and discharge, and so their weight will change appreciably."
Are Batteries Heavier When They're Full? (with Robert Llewellyn!) | Tesla
"This effect will make a charged battery ever so slightly heavier than a discharged battery because it has more energy. But the change is very small. Other types of batteries will absorb or release gasses during charge and discharge, and so their weight will change appreciably."
Are Batteries Heavier When They're Full? (with Robert Llewellyn!) | Tesla
well maybe it's a super sensitive scale!
"This effect will make a charged battery ever so slightly heavier than a discharged battery because it has more energy. But the change is very small. Other types of batteries will absorb or release gasses during charge and discharge, and so their weight will change appreciably."
Are Batteries Heavier When They're Full? (with Robert Llewellyn!) | Tesla
Stephen Crothers and other such heretics would likely disagree
WileyTheMan
Peanut Gallery Member
SageBrush
REJECT Fascism
That was my first thought too ... and my later thoughts were not very complimentary.
But we might as well be literal before we get drunk and embrace the new year:
One electron volt (EV) is ~ 1.6 * 10^-19 joules
An electron weighs ~ 9.1 * 10^-28 gram
If we figure that a full battery is at 400v and holds 75 kWh = 2.7 * 10^8 Joules,
Then one EV of 1.6*400*10^-19 joules at 400 volts = 5.6 * 10^-17 Joules
So we add to the battery ~ 5*10^24 electrons which weigh in aggregate ~ 0.0044 grams
Just in case our American friend has trouble with metric, it takes one pound of electric energy to charge 100,000 Model 3 LR batteries to full.
----
I might as well admit it -- the above is wrong because the electrons are already in the battery; charging just increases their potential energy. But for giggles I imagined that the electrons have to be added.
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Can we count it like this? Whatever electron flows out on the negative terminal, will flow back into the battery on the positive post.
Not sure if there is any chemical reaction that might change the molecular weight. Like fumes or something.
SageBrush
REJECT Fascism
You do not add electrons to battery - you move electrons/ions from one side to the other so the difference in weight will be due to relativity. I.e. m = E/c^2, so approximately 72 kWh / (3*10^8 m/s)^2 = 72000 kg*m^2/s^3 * 3600 s / (3*10^8 m/s)^2 = 20 / 9e16 kg*m^2/s^3*s/m^2*s^2 = 2.2e-16 kg = 2.2e-13 g...
Now I wonder how much would the weight of the battery change when you gain 1000 feet of elevation
dhrivnak
Active Member
No electrons and ions migrate from the cathode to the anode. No matter flows in or out. Now you will get slightly less performance as you have a lower starting voltage and more sag as the battery is discharged.
insaneoctane
Well-Known Member
dhrivnak
Active Member
Yes. Test it yourself.
1. Run pack empty.
2. Take out the pack
3. Weigh it.
4. Put it back in.
5. Charge it full.
5. Repeat steps 2 through 4
1. Run pack empty.
2. Take out the pack
3. Weigh it.
4. Put it back in.
5. Charge it full.
5. Repeat steps 2 through 4
smicker
Roadster 1020
Not sure if batteries weigh more but I do know for a fact that Auto Pilot makes the car heavier when enabled on freeways.
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