Chevy Bolt EV Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
I recently got a 2018 Bolt, after driving a 2012 Volt, and am curious about the total energy consumption to charge the battery. With the Volt and a 110V charger and a Kill-a-watt meter, I could see that the total energy was around 13.3 KWH to put around 10.6 KWH into the battery. Now, I'm using a 240 V charger so I can't accurately measure consumption.
Does anyone have numbers from GM, or their own experience, showing what the total consumption is for charging the nominally 60 KWH battery pack?
 

·
Registered
Joined
·
2,074 Posts
The EPA assumes the efficiency of charging (needed for their MPGe calculation) is 89%. How efficient it is can vary in my experience (e.g., when the battery is colder charging less efficient, but warmer cables have higher resistance). In my experience comparing kWh used reported by the car and kWh supplied reported by my JuiceBox Pro, it seems to be about 90% efficient, sometimes more, sometimes less.

One of the reasons I bought a JuiceBox Pro is that it provides me enough information to me to obsess about these things.
 

·
Registered
Joined
·
676 Posts
I setup an extra current tap for the Bolt on my internet connected whole house metering system. I had to apply a ratio of 1.33 to make it read properly. I suspect it is a power factor issue (has to do with inductive loads on AC line). Switch mode power supplies are known for bad power factor. Anyway, my calibration adjustment seems to jibe with your reading as well.
 

·
Registered
Joined
·
146 Posts
I typically put 72kwh for a full charge (from dead 0-1 percent). I have a dedicated meter for this L2 charger.
110V is probably not as efficient.

I can typically get 61 to 62kwh worth of driving and I assume the battery is a 65kwh battery not 60Kwh as people keep mentioning here.

Pretty good efficiency (90 percent charging and 95% driving)!
 

·
Registered
Joined
·
163 Posts
I have a 240V charger that displays the power consumption. The difference between the charger power consumption, and the addition of the energy to the car, is about 5-10%.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #7 ·
I appreciate the responses. Seems like 90% efficient is a good number to use
I have been assuming around 48 KWh was roughly what the battery gained in going from 0% to 100% charged (i.e. 80% of a 60 KWh pack), but from fbitz777 experience, I assumed wrongly.
Since I'm not an electrical or electronics engineer, it's easy for me to get lost in the nuances of charging.
My goal was to be able to realistically answer friends' questions when they ask me about the cost of charging, and, of course, the cost per mile to compare to an ICE vehicle. I can make a reasonably good estimate of my average range and can identify my KWh cost (off peak, demand time of use) easily, so the remaining variable is the KWh being drawn for a charge. Looks like I need to assume around 72 KWh going in for a 0-100% charge.
Still welcome other comments/experience/corrections.
Thanks to all responders.
Bruce
 

·
Registered
Joined
·
146 Posts
Please note that my numbers are when I am real zero SOC i.e. the car is not going to move much more.... you typically have 5 percent or 10-15 miles from the time the display stops showing range.

Best percentage indicator is via the app. Counting the bars is actually pretty good too but at 5% resolution
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #10 ·
This afternoon, I started a chat with Chevrolet to try to see if they could tell me the KWh the vehicle adds when it goes from 0% to 100% SOC. They dodged the question, said they were looking in the owners manual and then said I should contact the dealer. I then specifically asked if they could put me in touch with an engineering type, at Chevrolet, to get the answer. Surprising to me, they did not seem interested in even referring me to someone else. Discouraging.
Reason for the chat was that Fbitz777's earlier response surprised me (the 72 KWh) and I wanted to see if they could confirm.
 

·
Registered
Joined
·
1,165 Posts
Here are some numbers.

Level 2 is 86.4% efficient
Level 1 is 83.7% efficient

But it is more nuanced, depending on length of charge and ambient temperature. The report below is informative.

https://www.veic.org/docs/Transportation/20130320-EVT-NRA-Final-Report.pdf
Interesting, though that study if 5 years old an EV technology has changed quite a bit since then. Would love to see a fresh look at the data with a modern EV like the Bolt and higher output EVSEs.
 

·
Registered
Joined
·
1,165 Posts
Surprising to me, they did not seem interested in even referring me to someone else. Discouraging.
I'd have been surprised if they had even entertained the idea of escalating your question up to engineering. For a big company they put a lot of effort into making sure they don't say/print anything that isn't carefully controlled by teams of lawyers and marketing weenies.

I used to work for a subsidiary of AT&T and the amount of effort that our (software) engineers had to expend to get approval to do something like speak at a conference was enormous.
 

·
Registered
Joined
·
786 Posts
Now, I'm using a 240 V charger so I can't accurately measure consumption. Does anyone have numbers from GM, or their own experience, showing what the total consumption is for charging the nominally 60 KWH battery pack?
Easy! Take a reading of your utility power meter before and after the charge. Subtract the two and the difference is your energy consumption. It may not be "exact" but it is the cheapest and uses only you as a resource.;)

I see no reason to worry about "energy losses" charging a BEV. You have many "gasoline losses" even while refueling your ICE., yet you never complain about that.
 

·
Registered
Joined
·
11 Posts
I asked the same question at three different dealers, one even contacted GM, no one could answer the question in a way that I could easily relate. Now that I own, I explain it in terms of cost per mile. The amount of Kwh used each time I drive is very close to what it takes to recharge. If I use 18 Kwh to drive (according to the Bolt energy screen), it takes about 20 Kwh to re-charge at the house, level 2 32 amp. It's so close, and other variables impact the numbers, so I just talk about the average driver experience. If it takes 1 Kwh to go four miles, and 1 Kwh costs us 10 cents, that's 2.5 cents per mile. (Plug in your own electric costs) Compare that to what it costs to drive an ICE. If you pay $2.50 a gallon, and get 25 miles to a gallon, that is 10 cents per mile. Thus, the cost of the EV vs. ICE is a quarter of the cost. (.025 vs, .10) That doesn't take maintenance into consideration, which should be much less with an EV, no engine, no oil, etc...
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top