Actual Miles per Kwh different than the car dashboard miles per Kwh

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After many days of testing the car energy use I realize that the actual miles per Kwh I'm getting is different than the miles per Kwh that the car says, the car would stay around 4 to 4.5 Miles per Kwh, and I thought while may not be accurate should be close enough, after driving many times in slow roads (45-50 Mph) with the a/c on (85 F outside) and going back to see how much energy it took to drive, my math comes out to about 2.9 Miles per Kwh, that's a lot lower that what I would expect, am I missing something? while I understand there a loses in the wiring and charging it seems like the difference is too much.
 
You do not provide important details but you appear to be comparing energy to drive a mile to energy pulled from a meter to drive a mile. They are not the same.
 
You seem to enjoy driving yourself crazy over insignificant information...

What is really important is that you have enough KWh to get you to where you want to go...

When you plug in, what do you care if you need a couple more or less volts of juice from your charger??
 
What I meant was the energy economy of the car, so I just wanted to calculate the cost per mile, and I always used the average that the car was saying, but after using a watt meter to see how many kwh it takes to drive a certain amount of miles it came out about 2.9 Miles per each Kwh which is way lower than the 4.4 the car says, so each mile cost more than what I thought it did.
 
Two mistakes:

1. I mentioned earlier
2. You are using the car meter average since it was last zero-ed, compared to the last charging event.

Your results are unreliable.
A simpler and better way is this:

Charge up to 80% SoC (or whatever)
Go for a typical drive(s) and note the miles driven
Recharge up to the same SoC as (1)

Calculate miles_driven/kWh_charged
 
My 2011 routinely displayed 4.0 mi/kWh on the dash (reset each charge cycle) while actual miles driven divided by actual energy from the wall (240-volt L2 charging) was about 3.0 mi/kWh. The 2015 is more efficient because the higher L2 charge rate minimizes the overhead charging losses. The 2015 calculates to about 3.5 mi/kWh when dash displays 4.0 mi/kWh and charging is from 240-volt, 30-ampere EVSE. These results are based upon discharge to very low battery warning so that a large percentage of the charge cycle is at the highest charging current (charge rate tapers as battery gets close to full charge so charging efficiency drops).
 
Deoc said:
After many days of testing the car energy use I realize that the actual miles per Kwh I'm getting is different than the miles per Kwh that the car says, the car would stay around 4 to 4.5 Miles per Kwh, and I thought while may not be accurate should be close enough, after driving many times in slow roads (45-50 Mph) with the a/c on (85 F outside) and going back to see how much energy it took to drive, my math comes out to about 2.9 Miles per Kwh, that's a lot lower that what I would expect, am I missing something? while I understand there a loses in the wiring and charging it seems like the difference is too much.

Also if you're using a kill-a-watt meter to measure how much energy you're are consuming you are charging at 110/115V which is much less efficient that 220/230V charging so that's a significant part of your "discrepancy" however the in dash display only shows vehicle operation consumption rate & doesn't factor in charging losses &/ or inefficiencies
 
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