Is there a forumla to know the cost for each Empty-Full EV charge?

6.4 * 17c

Bob Wilson

 

Is it 6.4 KWh useable for EV? I was guessing more like 5.5-6KWh, once you subtract out charging overhead and HV-operation space...


iPhone ? Pro

 

I measured it: Prius Prime Plus in my hands | Page 7 | PriusChat

Correction 6.3kWh for a full charge in Rhode Island and 6.35kWh in Huntsville AL.



Bob Wilson

 

I only measured it once, but it was 6.6kWh (from L1) that one time.

 

@Lee Jay brings up a good point that there is some variability both in the battery, charging conditions, and systems making the measurement. So I am confident that 6.4kWh is a perfectly fine and usable value. It is subject to variability as someone pointed out that slower charge rates are less efficient that faster ones.

Bob Wilson

 

It's also variable based on the amount of hybrid-charge left in the battery when you shut off the car.

 

I recorded 6.41 kwh using a 120v evse metered thru a kill-a-watt meter once.

Excellent point about charge left in hybrid portion of battery.

our electric rate is 0.11/kwh with taxes, so a full charge of EV portion of battery costs about 70 cents at home.

 

are the ~15% charging losses included in the 6.4 figure?

 

Yes although the losses vary by the voltage:

• 240 VAC - home EVSE @16A (lowest)
  
• 210 VAC - business EVSE @16A
• 120 VAC - home EVSE @12A
• 120 VAC - home EVSE @8A

Bob Wilson

 

try this, I think this does what your looking for

MPGe Cost Comparison Calculator

 

The losses do not play a role in the electricity cost. You are buying both the energy used and the energy lost.

 

I gather the OP's goal is to get a handle on the total cost, including charging in/efficiency.


iPhone ? Pro

 

The total cost is what you take from the mains. It includes eventual losses. Of the 6.5 kwh you probably get 5.5 kwh or so in useful energy, but you pay for 6.5.

 

I have charged with 0 miles left 4 times 6.48 - 6.35 - 6.50 - 6.39 for an average of 6.43

 

Informed data is a great thing.

 

One of the reasons L1 charging is less efficient than L2 charging is due to the losses in the charger electronics, which are more or less constant per unit time, but L1 charging takes more than twice as long as L2 charging, due to the voltage difference and since at 120V, the car only accepts 12 amps, but accepts 16 amps at 240V.

 

They're more likely to be constant per unit time only if current is constant. Lower current will have lower losses.

 

I used th think the same until I looked at switching regulator data sheets.

Bob Wilson

 

At 240V the charge from the wall (payable energy) is only about 6 kWH as reported by @GT4Prius