The Prius Prime is a dual fuel vehicle, able to run 100% on Electric, or 100% on gasoline, or a computerized blend in-between. This presents me a great opportunity to be able to do a direct comparison with the same car of an EV engine vs an ICE engine.
-
Toyota computer claims 3.2mi-per-kwhr.
-
Kill-a-watt (https://en.wikipedia.org/wiki/Kill_A_Watt) claims 2.2mi-per-kwhr.
-
Additional 1.5% losses should be assumed in the wires if you wish. (120V drops down to 118V during charging, meaning 2V of the energy was lost due to the resistance of my home’s wires).
-
Level 1 charger at home (known to be less efficient).
-
Toyota computer claims 53miles-per-gallon (American Gallon).
-
I have not independently verified the gallon usage of my car.
-
295 miles driven total, sometimes EV, sometimes Gasoline, sometimes both.
-
30F to 40F (-1C to 4.5C) in my area this past week.
-
Winter-blend fuel.
-
12.5miles per $electricity-dollar (17.1c / kw-hr home charging costs)
-
17.1 miles per $gasoline-dollar ($3.10 per gallon last fillup).
If anyone has questions about my tests. The main takeaway is that L1 charging is so low in efficiency that gasoline in my area is cheaper than electricity. Obviously the price of gasoline and electricity varies significantly area-to-area, so feel free to use my numbers to calculate / simulate the costs in your area.
There is also substantial losses of efficiency due to cold weather, that is well acknowledged by the EV community. The Prius Prime (and most other EVs) will turn on a heater to keep the battery conditioned in the winter, spending precious electricity on battery-conditioning rather than miles. Gasoline engines do not have this problem and remain as efficient in the winter.
I have a 2021 prime and also concluded that gasoline is cheaper than running on electricity. I actually only charge up when charging is free. I don’t live in extreme cold, but most of the issue is electricity is so expensive near me that it actually negates any savings.
You have a lot better math than I did though, so Kudos.
With a 32% loss between wall and miles-driven, (assuming Toyota’s battery meters in the car are accurate) there’s clearly something going on here. I’m thinking L1 chargers are extremely inefficient. It is well known to anyone charging their car that the battery fans + heater turns on when you plug it in the winter. You can literally hear the battery conditioning turn on.
L2 chargers are faster, meaning battery conditioning (be it fans for cooling, or heat for the winter) will be run less. Ex: If you charge 3.5x faster on L2 there will be 3.5x less battery conditioning, leading to more efficiency.
Its a fools errand to “try to save money” through this however, as buying new L2 chargers will likely cost you $thousands, and the Prius Prime already cost $thousands more than a regular Prius. So do this because you’re a believer in electricity (ex: lower emissions, nuclear/solar power use, reduction in oil and/or geopolitical issues with the Middle East, yadda yadda). But DON’T necessarily do any of this to save money, the math just isn’t adding up for me yet.
Yeah — I mean, it’s really just a feature of the PHEV that we get to compare gas vs electric. And, the Prius is THE most efficient hybrid. So it’s a tight comparison. If you’re going from a gas guzzling truck or SUV to an EV in the same class, you’ll probably save money. And, if you don’t, you’ll definitely be doing the right thing anyway and probably end up with better overall features and tech than you currently have.
My level 2 charger cost $600 and I paid an electrician to install a 240V plug for 2 hours and parts (~300 IIRC). I wouldn’t say “thousands”. Maybe a thousand plus some if you want a fancier charger.
How far did the electrician have to run the new line for you?
My case will be cheap. But I have coworkers who needed like $1500 in labor costs to run a wire like 40 feet through 4 different rooms on different floors.
Garage vs basement circuit breaker on the other side of the house… Lol.
Really depends on your location. Around me, it’s hard to get an electrician to do any job that doesn’t at least cost $1500. $500 would get you an unlicensed guy to do it under the table, unpermitted.
I live in a large city suburb. It was a licensed electrician. Still $300ish.
External conduit in the garage, about 12ft, so not terrible.
I just did some napkin math using Google research numbers. On average L2 charging appears to be 7.3% more efficient than L1. (83.8% efficient for L1, 89.4 for 2… and the percentage increase is not subtraction problem for anyone wanting to poke at my math).
So using your electricity-only efficiency numbers, you would still only get: 12.5 * 1.073 = 13.41 miles/dollar.
It’s partially subtraction.
The 100W heater (or whatever it is…) to condition the battery in the winter is a subtraction problem, not a multiplication problem. The heater needs to run during the winter when charging or when driving.
1100W L1 charger - 100W heater is less efficient than 3500W to 10,000W L2 charger - 100W heater.
Now there is another component of multiplicative losses (the inductor and/or voltage conversion coil + MOSFET switch resistance). So it’s partially subtraction and partially multiplicative losses. Ultimately I’ll need to just test the damn thing to find reality, we can’t math this out on paper. (100W losses I assumed earlier was just that, an assumption. I have no idea how much the battery conditioning circuits / pumps / etc. uses up in practice)
The real problem is that I’m not aware of any Kill-a-watt model for 240V circuits. I’ll have to rely upon the charger to give me accurate readouts. But all the theory (and apparently some internet testing) suggests that the
You can look into a current clamp meter as a stand in for the kill-a-watt. If you’re willing to tinker a bit and like automation, you can use one of those and an esp32 board to make a remote power monitoring system for your 240v circuit.
If you’re less willing to tinker you can get some off the shelf stuff that you run the wires through or a clamp style variant to do something similar.
(Note: I can’t provide any recommendations on off the shelf products, I just bought the clamps and am working on tinkering it together).
Hmmm, current is the bulk of it. But voltage drop is also important as that’d measure wire losses. (All wires have resistance and it adds up the longer the wire runs get).
But yeah, good idea. I’m actually into electrical engineering so ESP32 is right up my alley. I mean, I prefer AVR but any uC can be used in that circumstance.