About how much does it cost to power an electric car at home?

Factual Questions
1

My neighbor says her son is moving back home for financial reasons (loss of job, and he thinks this area has better opportunities for him) “temporarily” and while she’s happy to have him, she’s wondering about the cost to her. She doesn’t want to profit off him or anything like that, but she’s a retired woman on Soc. Sec. plus her savings and needs to be mindful.

She has a pretty good guess as to how having him there will impact her food bills, based off how they were before he left for college about six years ago, but he has an all electric car now. She says he said he’ll be able to just charge it by plugging into a regular socket over night each night, no extra equipment, but any guesses as to how much that will likely boost her monthly bill?

I know it’s going to be affected by how much he drives each day, and without a set commute right now, who knows? But just a sort of ball park figure for her to guess from?

I suggested she just have him pay the difference between her previous monthly bill and whatever the new amount is, maybe? Or, since he’s apparently a healthy young guy, drop her lawn care and snow plowing service contracts and he can fill in for them as his ‘rent.’

Actually, I bet the impact on the grocery bills is probably going to be way more significant than she’s guessing right now, given inflation, but I’m just guessing.

2

For an extremely rough estimate, take miles driven, divide by 3 (3 mi/kWh is rough average EV consumption), then multiply by your local $/kWh cost.

I pay about $90/month to do about 1500 miles a month at $0.17/kWh but some states have slightly cheaper electricity and some are like three times as expensive.

3

As a lot more than charging the car is going to come into play, a better idea is to use her electric bills. Figure out last years 12 months and just have the son pay the difference between each month. Same for Gas, Water & Sewer. This should cover extra costs that are hard to track otherwise. Cooking, washer/dryer, dishwasher, showers, computer use, lights and etc.

Food is possibly tougher, but if she pays by credit card, this is also easy. You can sort and filter for supermarket payments to figure out prior costs vs going forward.

4

If he hops into his whiz-bang electric car and does his own grocery shopping, this one won’t be an issue :wink:

I’d probably recommend that he pay directly for any and all things for which he could pay directly.

Minimize the messy stuff where math applies.

ETA: Found a source that directly answers your OP question. I’ll leave it to others to opine on how close to their experiences these numbers are:

5

By far the smart thing for Mom to do here is look at it as an arms-length roommate situation, NOT “Her son is coming ‘home’.” Mom’s house is not son’s home. Hasn’t been for years now and can’t be going forward. Can be a temporary stopover, but the less mingled the better.

To the degree possible, son directly pays all his expenses. His groceries he bought with his money are on the left side of the fridge, hers on the right. etc. Don’t be offering to pick stuff up for the other person; that way leads to a 90/10 distribution of who’s paying and who’s taking.

As to the narrow Q of the OP … His car will be able to tot up how much electricity it consumed in a month plugged into Mom’s place. Net of course of any charging he’s done elsewhere along the way. Then you just look at Mom’s bill to convert kWh to dollars at the local “exchange rate”.


The prognosis for this all hugely depends of course on whether son is a wannabe flake looking to corner Mom into funding his couch potatohood, or is a diligent not-yet-success who has a realistic shot at finding that job, getting hired and staying hired. And then moving out timely. His skills, temperament, and ambition matter hugely. As does the fit between what he can do and the jobs available in Mom’s part of Mom’s town.

If son is a wannabe flake, it will end with him on the couch and her paying for everything. Two years from now you’ll be back telling us your broke neighbor lady wants to know how she can sell the house out from under her squatter to get grocery money for herself. A flake can outlast a decent person every time. And a young one can outlast an old one every time too.

If son’s character is for real, that’s less of a problem. But not no problem.

[Story time]

    As it happens, despite being a semi-wealthy recently retired guy, I just spent 3 months flopping at a friends’ house. I abruptly left my wife of 2 years back in January and needed a place to stay until some of clouds of divorce dust had cleared a bit and I knew where on Earth I wanted to live.

    He and I are both retired, both very comfy. He insisted I pay the going rate as shown on Zillow for renting a room in a suburban house in the same general neighborhood as his house. I insisted the same. Why? It keeps us both honest.

    Turns out that was $1,250/mo for a furnished bedroom and dedicated bathroom. Neither of us noticed the money changing hands; it was a drop in our respective and similar buckets. But the thought is he didn’t want to attract a couch potato. And I did not blame him for that. I knew I’d be motivated to get out as soon as practicable but he did not. Or at least not with the same rock-solid certainty I did.

    Anyhow, 3-1/2 months and $4,375 later I moved out and into my permanent housing a few miles away. He was sad to see me go; he kind of liked having a roommate to yak with during the long days in a big house. I miss him too and we still eat out together once a week or so. But no friggin’ way would I have put up with living that way for long. Given the alternatives I could afford.

[/story time]

Taking this example and re-applying it to the OP’s neighbor and both her and Sonny’s more straitened circumstances.

Mom’s real problem is to make sure her alternative is only slightly cheaper than what Sonny would pay on the economy. A little subsidy is OK; that is her offspring we’re talking about, not some random friend of just a few years. But it doesn’t take much subsidy to trap him there.

She should look up on Zillow the going rate for rooms to rent in houses in her area. Whatever that average number is, that is the rent Sonny must pay as soon as he has a paycheck, and ideally starting from right now depending on how broke Sonny is. Written deal.

The big danger for Mom is that Sonny can find a job that pays spending money but not rent money. Those kinds of part-time jobs are easy for the ambition-lite to get and keep. So he’ll take the job, spend all the money on entertainment however he defines that (GFs, drugs, booze, pay-per-view TV, comic books, etc.) and be too broke to move to his own apartment and it’s too hard to get a better job since he’s not building up a cash cushion to carry him across the gap. Pretty soon he brings a GF home and Mom’s costs go up even more.

IMO Mom is starting down an exceedingly dangerous road that has bankrupted many a little old lady. Only she knows her son; I sure don’t.

My late wife (not the one I just walked out on - that one was #2 and a rebound mistake) was a banking attorney and her firm dealt with lots and lots of cases of Moms or aunts taking in what started as legit family hardship cases that turned into ne’er-do-wells that then turned into thieves stealing the old ladies’ money out from under their increasingly blind noses. Of course we only heard about the bad cases, not the successes. But there are plenty of bad cases, and the worse the economy at his SES and Mom’s location, the more that’s gonna be true.

6

Same same–our Lyriq is about 3 miles/KWH and we put about a thousand miles a month on it at $.15/KWH. So about $50? And this is a heavy powerful car.

7

What if they want to eat together?

What if they want to trade off who cooks on different nights, or who cooks for who washes, or any of a batch of other possibilities, instead of each carefully spending time and dirtying pots making meals in which every morsel is carefully assigned to one or the other of them?

What they do need to do is to sit down and sort out, explicitly, how this is going to work, who is going to be responsible for doing what, and who is going to pay for what. Put it in writing; there can be genuine discrepancies in memory. And if they can’t come to agreement – then don’t do it.

8

According to my car’s app, in the last 31 days I charged 301 kWh for a total of $38. I try to charge mainly overnight when the rates are cheaper (I think it drops to 0.13 per kWh after 6PM)

9

If overnight charging on a standard outlet is just enough, then we’re talking in the ballpark of 40 miles a night. Most mid-size EVs can charge at about 4 miles/hour, and if we assume about 10 hours then we have 40 miles.

That’s about 12 kWh, so if your night-time rates are about $0.15, then that’s $1.80 a day or $54 a month. Which is also the same ballpark that a couple other posters have come up with.

If you really wanted to be super-careful about it, you could look up the per-hour usage on the bill or utility website. Most offer this information these days. It’ll easy to see the spike in usage at night when the car starts charging and figure out the kWh use from there. Multiply by the nighttime rates and go from there.

10

In theory, sure. In practice, maybe not. I have a 2023 ID.4 and as far as I can tell, it offers no reporting (in the car or the app) about cumulative charging over time.

11

Slight hijack, but do most power utility companies charge a flat rate over the course of 24 hours? Seems I read some charge less per kWh in the middle of the night (when an electric car would typically be charged) vs. daytime.

12

This is really the punchline. And much better-said by you than my micro-example folks were implicitly supposed to generalize from.

As you say, if they can’t reach a detailed agreement, or Mom’s assessment of Son’s character is such that she is confident the written agreement will mean very little a month later, then she ought not go thorough with it.

In either case its about viewing this as an arms-length transaction, not a mother-son transaction. How exactly they each decide to hold that view and how they enforce it is up to them. But if he’s thinking “sponge off Mom”, then it almost doesn’t matter what approach she walks into negotiations with; sponge wins every time it moves in. Although the more defensive her posture at negotiations the more she’s likely to perceive his sponging intent and veer off before it’s too late.

Of course I could be being grossly pessimistic and this guy is a paragon of ambition with plenty of good interviews already scheduled, etc. OTOH, that’s not the way to bet given the near-zero info the OP has shared with us about the larger picture.


Since that wasnt the point of this thread and I’ve now hijacked the crap out of it. :man_facepalming: I’m a dum-bass today.

13

Thanks for the info about the electricity cots, all. Too bad: according to that chart, Mass. is 49th highest in the nation, only beaten out of last place by Ct. Still. It’s not all that uncomparable to paying for gas, is it? Somehow or other, you going to pay, even if it’s for bus passes. My brother started out commuting on a motorcycle fresh out of college. NOT the most wonderful option in New England winters, eh?

Okay, yeah, I really didn’t give much background, did I?

Actually, I’m pretty optimistic on this working out pretty well for them. We’ve been neighbors of their family for decades. We’re about a generation older than the mother/deceased father, so not koffee klatch type friends, but we’ve interacted happily with almost never any friction. (There was that one pet dog…)

The kid, let’s call him George, he deserves a respectable name, has always been a good one. He sometimes pulled silly stunts and had loud parties with his friends, but – teenaged boys, right? No significant legal problems. He got good enough grades in HS to get a full scholarship to a pretty decent school, and graduated on schedule. My hubby helped get him a job at his work place after freshman year, and he was well enough thought of to be rehired the next three summers. He got hired right away after his BS, working for a tech startup in CA – which is now busy shedding staff and likely to be completely gone soon, hubby thinks. This area (Boston suburbs) is lousy with tech type firms, so that’s on his side.

I think the real ‘danger’ is maybe what LSL hinted, being ‘trapped’ by being too comfy. Not in the not working sense, but mom will abso-positively be back to wanting to cook all his meals, do all his laundry, spoiling him as much as possible. He’ll have to fight his way out, I fear. :wink:

The only thing mom was concerned about was the money situation. Her reaction when he asked was “Of course! You’re old room is waiting!” and some thoughts about economic realities didn’t rise until later on. We were just doing some spit-balling about how much and for what he should pay, and how to determine it, and the electric thing was the big Neither of Us Had Any Idea factor.

Plus, several of his old gang are still in the Boston/Lowell area, so I think it likely he’ll end up in some roommate situation with one of them or a friend of a friend in the near-ish future.

Fingers crossed, anyway.

Thanks again!

14

Eversource seems to be one of the suppliers for the Greater Boston Area. Here’s a partial rate sheet:

Standard residential is $0.17/kWh. But that doesn’t include the actual supply. That varies throughout the year from $0.15-0.17/kWh:

However, from the rate sheet you can see they have an “optional time of use” plan, which would be better for EVs. And in that case, the off-peak distribution rates are only about $0.05/kWh. So if they have that plan, night charging might only cost around $0.20/kWh. Which is about $72/mo for ~40 miles/day.

15

My electrical rate is a tad under 10¢ per kWh. This adds about 38km at 240V 26A (I dumbed it down from 40A in case it pops the main breaker in peak A/C season).
I can schedule my Tesla Model 3 to start charging at 1AM. There is no peak metering or time of daty rates, but that’s when nothing else in the house should be running.

To totally fill th battery (I never let it run to zero, but theoretically) 0-100% (70kWh, 500km=300mi) would be theoretically $7 or by the charger stats, $8.60. By comparison, my BMW after 500km takes about $90 (Canadian, $1.68/liter for premium, give or take)

My Tesla would actually tell me how much kWh per km I usedwhich ranges between 0.14 and 0.4 and even more in deep winter. (Also note that A/C or heat is per minute consumption, not per mile, which is why it can vary quite a bit) Also, an electric car uses regeneration for slowing down unless you push on the brake, and there’s no such thing as “idling”; so stop-and-go is more efficient than a gas car.

The real question is - how does he charge? I had a special 240V (NEMA 14-50) plug with 50A breaker run from my breaker panel to the garage. Some garages have this already for power tools like welders. Charging from 120V household outlet is painful. (3mi added per hour).

So here’s my advice - take the odometer reading each month, if true that he charges only at home (cheapest option!); then take number of miles driven, and use some number between 0.2 and 0.33 kWh per mile as the basis for calculation unless you can capture the approximate number kWh/mi from the car’s controls.

So let’s say he drove 600 miles that month. 600 miles x 0.33kWh = 200 kWh.
At an exorbitant 17¢ per kWh that’s 200x17¢/100= $34

Who fills up their gas tank for $34 once a month? And that’s the upper limit, 0.33; I’d use 0.25 which would give $25.50.

So the answer is - it’s not zero but it’s not breaking the bank, especially compared to gas.

16

If she’s old enough to be on Social Security, she shouldn’t have to go thru all these calculations.

Go with the plan where he pays the difference in the electric bill this month compared to the same month last year. Also gas bill, water bill, garbage, etc. Food they can work out.

Also, he should pay a reasonable rent. Start from the typical room rent in the area figure from zillow, etc.; she might reduce that somewhat if he is covering the increased utilities.

If she doesn’t feel right charging money to her own son, she can think of it as a forced savings plan. She sets the money aside in an investment account, and give it back to him later, like when he marries and buys his own house. Or even make it Transferable On Death to his name. Don’t tell him, that might discourage his work ethic. But she may feel better, knowing that he will get a happy surprise later on.

17

There are all kinds of “watt-meters” that plug into outlets or extension cords that will log the total power consumed over a period of time. They are quite inexpensive and readily available. It seems like this would be an objective way to keep track of the cost. I don’t have an EV myself, but if I did, I would probably buy one and use it just for the sake of understanding exactly how much electricity my car used and what the charging pattern looked like.

18

Let him either pay for all of the groceries, or all of the electricity. If he were my son, I’d have him go get and pay for the groceries and call it even.

19

That also would have the benefit of capturing the other electricity he’s using, like hot water and charging his phone.

20

Good to hear my initial hefty pessimism was almost certainly unfounded.

But this bit gives me pause:

[Story time]

    I met my now-late wife while we were both USAF officers in our mid-20s. She was a lawyer. After she did her 4 or 5 years she returned to her hometown which also where she had attended undergrad and law school. Lotsa friends, lotsa law industry connections. Familiar with town, etc. All sound planning.

    She had last been stationed overseas, so her first real day as a civilian was also her first real day in the USA after several years overseas. Finding a job via remote control was a lot harder back then when you had to use snail-mail. So she “temporarily” moved into her Mom’s house while she was finding that first job, getting a US car, etc., etc. All of which didn’t take long.

    Mom was always a domineering sort, but not in a mean way, just an oblivious way. Picture a blind cow in a China shop. No intent to hurt anyone, but lots of broken crockery wherever she turned. Mom basically proceeded to take over her daughter’s life and reduce her range of action to being a 10yo again. Mom poured soooo much guilt on this not quite 30yo professional woman that she could. not. break. away. Mom had captured her orbiting planet that would always face Mom and shine back at her all day every day and Mom was ecstatic. Until daughter wanted to change jobs, move out, etc. Then the guilt carpet bombing would start. Until her daughter caved and abandoned those plans.

    She and I kept up a long distance relationship during this fateful time that came close to falling apart more than once before I finally said to myself and her: let’s do it or don’t, but I’m ready to do it. So was she.

    Mother, who had known me for 5 years now and thought very highly of me, was devastated that I would steal her daughter away. That was her property to control. Not mine to take. Her own daughter had become, not a powerful high achieving member of the community of whom Mom was justifiably very proud, but instead had turned into her personal property. A pet if you will.

    We married, and new wife moved to my nearby state into what had been my house, now ours. In many ways it resembled an intervention like rescuing a “brainwashed” cult member. But she wanted me to do it and I did. Without malice or anger towards Mom, but with total implacable overwhelming force of will.

    It took Mom another 5 years to get over past that offense against all that is right and good. My wife never forgave her mom for those years trapped in her home, and then the 5 years in emotional exile after we got married.

    She and I were happily married for 33 years before she died. Her Mom was then still alive and I was taking care of her for another 2 years before she too died. To her last breath Mom never understood why there was a rift between them.

[/story time]

I hope like hell your Mom and son neighbors can avoid that particular psychodrama. There were years there that were pretty darn tough.