A way to estimate how many kW/year needed for 12k or 15k miles?

[Rothgarr]

Howdy.

We have solar on our roof. Right now I estimate we generate an excess of a little over 4,000 kWh/year since we replaced some appliances.

While we get money back from the electric company for our overproduction, it's peanuts. I'd rather use that excess to save money powering a car. Currently, I'm looking at a Model 3 Standard Plus, or a Chevy Bolt.

I'm trying to figure out roughly about how many kWh/year to charge it would take if I drove either 12k or 15k miles a year. Is there a way to figure that out so I could tell how much of that 4k excess (or more) we'd use?

 

[Rothgarr]

Actually, maybe I figured it out myself...

If I use the info on this page:
https://www.fueleconomy.gov/feg/Pow...&sortBy=Comb&tabView=0&tabView=0&rowLimit=200

It says the Chevy Bolt uses 28kWh/100mi

So if I wanted to figure out 12,000 miles, I'd do:

12,000 miles a year / 100 mi * 28kWh = 3,360 kWk/year to charge
15,000 miles a year / 100 mi * 28kWh = 4,200 kWk/year to charge

Is that right?

Then for the Tesla it says it uses 26kWh/100mi, so

12,000 miles a year / 100 mi * 26kWh = 3,120 kWk/year to charge
15,000 miles a year / 100 mi * 26kWh = 3,900 kWk/year to charge

Is that all correct?

 

[bwilson4web]

Yes but my Standard Range Plus is rated at 25kW/100 mi.

Bob Wilson

 

[The Gadgeteer]

Since you average less than 50 miles a day you can also consider a PHEV like the Chevy Volt or Honda Clarity. That way you can drive all electric just about all the time but still have gas for those occasions when you want to make a long trip without planning charging stops.

 

[Rothgarr]

Since you average less than 50 miles a day you can also consider a PHEV like the Chevy Volt or Honda Clarity. That way you can drive all electric just about all the time but still have gas for those occasions when you want to make a long trip without planning charging stops.

The Clarity is what originally got me interested last year. I liked the idea of not having to worry about range anxiety, but more recently I think I'm ready to go full electric and also not have to worry about ICE maintenance, etc.

I currently have a Chevy Bolt on loan from a friend. I'm only using the standard plug that came with it. It horrifying how long it takes to charge (an hour for ever four miles of range -- that's over 50 hours for a full charge). I would definitely get a 240v charger installed regardless of the vehicle I wound up getting.

 

[bwilson4web]

Clarity is what originally got me interested last year.

My gateway was a used, 2014 BMW i3-REx. Nashville TN, 120 miles away, remains my minimum range requirement and the BMW i3-REx fully met our requirements. But last year when the VW Electrify America station came online at Manchester TN, I ran benchmarks comparing gas and EV travel to Nashville and the 'lessons learned' made my transition to a Tesla Model 3 very easy.

I would definitely get a 240v charger installed regardless of the vehicle I wound up getting.

A couple of years ago, we upgraded our electrical service from 100A to 200A. We also installed a natural gas, 16 kW, emergency generator and an external, NEMA 14-50 on a 50A circuit (40A usable.) This has worked out great.

Let me suggest using Plugshare.com. It is not vendor specific and each charging station has comments from those who have recently used them. Plugshare also has a trip planning feature which I've successfully used to plan EV only trips with our BMW i3-REx and now our Model 3.

GOOD LUCK!

Bob Wilson

 

[Rothgarr]

Speaking of charging times and kWh needed to charge... does it require more power TOTAL to recharge a battery from empty to full depending on the type of home charger used?

For example, lets say I was charging a Model 3 Standard from empty using a regular 120v plug. While the analytic part of me thinks it would take the same number of kWh to charge to full as if I used a 60 amp 240v plug. But part of me also feels like it's less efficient to charge so slowly and in the end might require more kWh to charge to full? Is this thinking rubbish?

 

[bwilson4web]

Speaking of charging times and kWh needed to charge... does it require more power TOTAL to recharge a battery from empty to full depending on the type of home charger used? . . .

It depends and some of them are vehicle specific:

• higher charge rates may require enabling active cooling, an overhead
• the built-in charger efficiency may fall off at either minimum or maximum charge rate
• batteries typically take a low rate charge more efficiently than a higher rate

In engineering, we often say: GOOD, FAST, CHEAP ... pick two.

A smart 240 VAC charger lets you manage when and how much to charge. So in the summer, I would charge our BMW i3-REx between 3-9 AM when the temperatures are coolest. This avoids having the battery cooler come on.

Bob Wilson

 

[Rothgarr]

Interesting. Thanks so much for the insight.

 

[Thevenin]

Speaking of charging times and kWh needed to charge... does it require more power TOTAL to recharge a battery from empty to full depending on the type of home charger used?

For example, lets say I was charging a Model 3 Standard from empty using a regular 120v plug. While the analytic part of me thinks it would take the same number of kWh to charge to full as if I used a 60 amp 240v plug. But part of me also feels like it's less efficient to charge so slowly and in the end might require more kWh to charge to full? Is this thinking rubbish?

The EPA rates EVs by wall-to-wheel efficiency, so their numbers are accounting for typical Level 2 charging losses and report the number of kWh the owner will have to pay for.

If you're using a Level 1 charger, then you're likely to see a penalty to efficiency. We can only guess just how much this is, but it's somewhere around 10%. Here is a thread where we've discussed this at length.