Charging Math, Miles Per Dollar - Is this right?

[phidauex]

12% charging loss sounds conservative to me, I measured the one way battery losses at 3% when DC fast charging, not including the hvac overhead since I was in the car keeping it cool during charging. The rectifier is probably 95-98% efficient, meaning the total losses from an L2 charger are probably more like 5-8%.

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[Auto Motive]

I just charged-up from 25% to 90% this week. My EVSE sub-electrical meter (City property) says I used exactly 65 kWh for this 65% charge! I pay only $0.1056/kWh rate for EV charging & $5/mo for sub-meter ($0.63/charge estimating 8 charges/month). This charge cost me exactly $7.49! Fordpass estimated I gained about 185 miles... So, grand estimated total cost per mile for me is 4 cents! Holly cow!

Our cost of gas in west. Pa is 3.55 gallon with pa tax highest in USA at .62....but our elect utility west penn power charges .06 kWh....one of the lowest in US. My wife has her GTPE and I waiting to see what Dodge has for the muscle cars of the future in 2023.

 

[RickMachE]

12% charging loss sounds conservative to me, I measured the one way battery losses at 3% when DC fast charging, not including the hvac overhead since I was in the car keeping it cool during charging. The rectifier is probably 95-98% efficient, meaning the total losses from an L2 charger are probably more like 5-8%.

My measurements are exact - i.e. as exact as the FordPass display of kWh is (since it doesn't show decimal places). I know how much electricity my charger uses, and I know how many kWh go into the car. The rest is math.

 

[RickMachE]

To get your low cost off-peak rate did you have to agree to a higher cost for other time of day rate usage.

To get a low off-peak rate my power company wanted to increase the normal rate as part of the offer. As we are home during the day we use enough power for lights, electronics, and cooling that the off peak rate savings would not have made up for the increased non-off-peak rate

Yes, we had to accept a higher cost during peak then the previous 24/7 cost.

HOWEVER, ...

I did an analysis 6 months before getting a Ford PHEV, the Fusion Energi. I was surprised to find that PRIOR TO GETTING ANY PHEV OR EV, it was cheaper for us to switch to the Time of Day plan than keeping the regular plan, except for a handful of summer days. The savings weren't extensive prior to getting a vehicle, but we switched early anyway.

Our Time of Day plan is peak from 11AM to 7PM M-F, i.e. only 8 hours a day, 5 days a week. The rest of the time, including weekends, is off-peak. If you move your heavy users of electricity (washing machine, dryer - even our gas dryer uses electricity, dishwasher) to off-peak, which we found easy to do, then the only big users during peak are things like the electric oven and the A/C.

We found that our normal usage put most of our usage off-peak. Our first month of the new plan showed 75% off-peak. That was pre-PHEV. Last bill, which was the period 9/25 - 10/25, our usage was 86% off-peak.

Per our utility, the normal residential rate is 15 - 17 cents (for us it was just over 16 cents). Time of Day is 12 cents off-peak, and 20 or 23 cents peak (20 cents is Nov - May, 23 cents is June - October). Their EV plan is 11 cents off-peak and 24 cents peak, so we'd save a penny off-peak but pay more peak, and that plan only has 10 hours of off-peak a day versus our 16 hours, and have to get a separate meter and pay to hook it up AND a monthly charge for it.

You can look at your usage, or do a breakeven analysis. If 70% of your usage is off-peak at 12 cents, and 30% of your usage is peak at 20 cents, that's 14.4 cents weighted average, vs. just over 16 cents, so you're already winning. Lower it to 60% and the weighted average is 15.2 cents, still a winner. Have to drop below 50% to lose on this rate and that's hard to do without A/C during the day. If you use the 23 cent rate, then it changes the math a bit, the rate goes above 16 cents when you hit ~62% not below 50%.

Of course rates change over time and you can't rely on them to stay the same. But, as long as that relationship holds, Time of Day works for us.

When I did our analysis in the Spring of 2018, our utility company had an app that showed historic usage. It was cumbersome, you had to rotate the dial to the hour, and get the usage, type that in, and then do the next hour. Of course I only had to do 8 hours, then subtract them from the total to determine the off-peak usage. Now, they allow you to download usage from their site into a spreadsheet, the previous 13 months, usage by hour. Would have been nice to have that back then.

I suspect in Maryland you would be the same as me, only losing in the peak hot days of summer, IF your rates had a similar relationship. Then, add in the EV, and the balance shifts even more.

 

[Riotous]

Ok, cleaned up and final. Note first charge from dealer not included, so last charge to top up to 90% is included.

Charged	Charged	Charging	Charge	Miles	Useable	Kwh	Charge Spd	Charge Spd	kWh	KWh	Cost	Cost
From	To	Time	Added	Added	Battery	Added	Miles / Hour	kWh / hour	Loss Rate	Used	$/KWh	$$
57%	74%	2:55	17%	38	88	14.96	13.03	5.13	10%	16.62	$0.116	$1.93
46%	100%	10:14	54%	132	88	47.52	12.90	4.64	10%	52.80	$0.116	$6.12
68%	90%	3:49	22%	53	88	19.36	13.89	5.07	10%	21.51	$0.116	$2.50
29%	90%	10:30	61%	139	88	53.68	13.24	5.11	10%	59.64	$0.116	$6.92
25%	90%	11:08	65%	147	88	57.20	13.20	5.14	10%	63.56	$0.116	$7.37
67%	83%	2:56	16%	39	88	14.08	13.30	4.80	10%	15.64	$0.116	$1.81
56%	90%	6:07	34%	84	88	29.92	13.73	4.89	10%	33.24	$0.116	$3.86
32%	90%	10:01	58%	140	88	51.04	13.98	5.10	10%	56.71	$0.116	$6.58
62%	90%	4:01	28%	57	88	24.64	14.19	6.13	10%	27.38	$0.116	$3.18
85%	90%	0:51	5%	12	88	4.40	14.12	5.18	10%	4.89	$0.116	$0.57
51%	90%	6:47	39%	90	88	34.32	13.27	5.06	10%	38.13	$0.116	$4.42
		69:19		931		351.12	13.43	5.07		390.13		$45.26
EVSE	Splitvolt		Odometer	953		2021 GTPE	miles / kWh	2.71		2019 F150	gas price	$2.75
Amps	24						MPGe (x40)	108.57			ave mpg	17
Circuit	30						$$ / mile	4.75¢			$$ / mile	16.18¢
Plug	NEMA 14-30						Miles / $$	21.06			Miles / $$	6.18
							x Factor	3.41
							MPQ equiv	57.91

Thanks for all the feedback.
Oh, fixed rate plan, total cost is 11.6 cents per kWh, it's possible to change based on delivery, but stable. Gas prices in Houston, TX, what we pay here. Was $2.79 yesterday when I filled the truck. Most of the driving is in Engaged Mode with 1-pedal on. Wife does use Whisper with 1-pedal off. About 30% of the miles driven.

 

[phidauex]

My measurements are exact - i.e. as exact as the FordPass display of kWh is (since it doesn't show decimal places). I know how much electricity my charger uses, and I know how many kWh go into the car. The rest is math.

Ah, ok, I thought the 12% number people were using was coming from the Car and Driver article as a generic value. I’ll measure my next charge too, I have a power meter on the EVSE input as well, and I’ll pull the kWh values from the extended PIDs which should give a few more decimal points.

 

[RWG]

Last week, we used a ZEF Energy DC Fast charger, for the first time, in Motley Minnesota. The instructions on the DC Charger said; $3 connection fee and 30 cents per minute of charging. I think that means 60 minutes of charging costs about $18 plus $3 or a $21 total. As I recall, the charging unit said we got about 41kwh of juice/power.

However, when I checked my credit card account, ZEF had charged a flat $30 and the transaction was "pending" . I called ZEF to find out: WTF? I was told, they always charge $30 then refund the difference when the transaction "settles". I find this rather dumb. Also, there was no invoice, report, regarding the session details. Just a debit on your card. As such, I disputed the charge on my credit card account, and my credit card company has already refunded the amount. So, ZEF Energy will be screwed until they reconcile the bill and fully explain the charge details.

Message to all:

I have learned that connection fees are variable, depending on location and provider. I have found connection fees that range from $3 dollars ( cheap) to $18 ( ridiculous). Also some charging units/locations charge by time, others by the KW. Interesting . . . I prefer by the KW, not time. I am not sure, but the car charging software may vary the charge rate over time but the real cost should be how much energy did you get versus the amount of time you are charging. Also, all DC charging stations are not created equally. The one I used could deliver a max of 41 kw per hour. As I understand it, there are higher capacity units out there, and I believe one of the last OTA software updates has features to limit DC charge sessions, to keep charging system components from over heating. The only way to do that is to control the KW charging rate, i.e. throttle it down, so again, paying by the KW seems to be the only valid charge basis.

None of us would tolerate buying gasoline by time at the pump. We pay by the gallon. However, it appears that many of the "EV charging station" providers have adopted a pricing scheme that is a bit questionable.

Bottom line, in my case, nothing on the road beats my "at home, in the garage, rate". No connection fees and about 15 cents per KW.



timbop: Regarding the ESVE power loss, inefficiencies. It is my understanding, the with electrical components, any power loss experienced turns into rejected heat. So, therefore if a 40 amp , 220V ( 8,800 watts) ESVE is losing 10%, the amount of energy loss, or waste heat would be about 880 watts, or 2992 BTUs of heat.( 3.4 x 880 = 2992) 2992 BTUs is a lot of heat, if concentrated in a small area. However, if it is spread out, i.e. adequate surface area, no big deal.

I have the Ford Charger System in my garage, made by Wabasto, and it indeed does reject some heat during a charging session, and so does the power charging cable. However, a 10% loss maybe a bit high, since the amount of heat rise I see on various components is about 10 to 20 degrees above ambient temps. In order to calculate the actual, precise loss, would require measuring the breaker box power draw and compare it to the amount of power the batteries ( KWH) absorbed. ( I am too lazy to do that!)

A practical example of sensible, heat, btus and surface area. A 60w, incandescent light bulb puts out about 680 btus of heat, but because the surface area is not even 1 sq. ft. the surface of the bulb gets very hot, well over 150 degrees F. But if the bulb globe were bigger, it wouldn't get so hot.

 

[RKinWA]

According to my ChargePoint app for my Home Flex, in May, I charged 403kWh, 1600 miles, and it cost me $40. Gas here is $4.59, so significant savings.

 

[Maquis]

Last week, we used a ZEF Energy DC Fast charger, for the first time, in Motley Minnesota. The instructions on the DC Charger said; $3 connection fee and 30 cents per minute of charging. I think that means 60 minutes of charging costs about $18 plus $3 or a $21 total. As I recall, the charging unit said we got about 41kwh of juice/power.

However, when I checked my credit card account, ZEF had charged a flat $30 and the transaction was "pending" . I called ZEF to find out: WTF? I was told, they always charge $30 then refund the difference when the transaction "settles". I find this rather dumb. Also, there was no invoice, report, regarding the session details. Just a debit on your card. As such, I disputed the charge on my credit card account, and my credit card company has already refunded the amount. So, ZEF Energy will be screwed until they reconcile the bill and fully explain the charge details.

Message to all:

I have learned that connection fees are variable, depending on location and provider. I have found connection fees that range from $3 dollars ( cheap) to $18 ( ridiculous). Also some charging units/locations charge by time, others by the KW. Interesting . . . I prefer by the KW, not time. I am not sure, but the car charging software may vary the charge rate over time but the real cost should be how much energy did you get versus the amount of time you are charging. Also, all DC charging stations are not created equally. The one I used could deliver a max of 41 kw per hour. As I understand it, there are higher capacity units out there, and I believe one of the last OTA software updates has features to limit DC charge sessions, to keep charging system components from over heating. The only way to do that is to control the KW charging rate, i.e. throttle it down, so again, paying by the KW seems to be the only valid charge basis.

None of us would tolerate buying gasoline by time at the pump. We pay by the gallon. However, it appears that many of the "EV charging station" providers have adopted a pricing scheme that is a bit questionable.

Bottom line, in my case, nothing on the road beats my "at home, in the garage, rate". No connection fees and about 15 cents per KW.



timbop: Regarding the ESVE power loss, inefficiencies. It is my understanding, the with electrical components, any power loss experienced turns into rejected heat. So, therefore if a 40 amp , 220V ( 8,800 watts) ESVE is losing 10%, the amount of energy loss, or waste heat would be about 880 watts, or 2992 BTUs of heat.( 3.4 x 880 = 2992) 2992 BTUs is a lot of heat, if concentrated in a small area. However, if it is spread out, i.e. adequate surface area, no big deal.

I have the Ford Charger System in my garage, made by Wabasto, and it indeed does reject some heat during a charging session, and so does the power charging cable. However, a 10% loss maybe a bit high, since the amount of heat rise I see on various components is about 10 to 20 degrees above ambient temps. In order to calculate the actual, precise loss, would require measuring the breaker box power draw and compare it to the amount of power the batteries ( KWH) absorbed. ( I am too lazy to do that!)

A practical example of sensible, heat, btus and surface area. A 60w, incandescent light bulb puts out about 680 btus of heat, but because the surface area is not even 1 sq. ft. the surface of the bulb gets very hot, well over 150 degrees F. But if the bulb globe were bigger, it wouldn't get so hot.

I hate adding to a necropost, but….

Most of the AC charging losses occur in the onboard charger, not the EVSE. That’s why you hear the fans come on during charging at times.

 

[kodiakng]

However, when I checked my credit card account, ZEF had charged a flat $30 and the transaction was "pending" . I called ZEF to find out: WTF? I was told, they always charge $30 then refund the difference when the transaction "settles". I find this rather dumb. Also, there was no invoice, report, regarding the session details. Just a debit on your card. As such, I disputed the charge on my credit card account, and my credit card company has already refunded the amount. So, ZEF Energy will be screwed until they reconcile the bill and fully explain the charge details.

clipping down to just this point...

what you're seeing is called an "Authorization Hold" and is quite normal, especially in PoS systems where the authorization comes before the final amount to be charged is known.

my copy session at FedEx Office today has a $10 hold on a charge that will be settled at $0.38.

you'll lose your dispute but you may want to be aware of why.

 

[dbsb3233]

clipping down to just this point...

what you're seeing is called an "Authorization Hold" and is quite normal, especially in PoS systems where the authorization comes before the final amount to be charged is known.

my copy session at FedEx Office today has a $10 hold on a charge that will be settled at $0.38.

you'll lose your dispute but you may want to be aware of why.

Yep. It's common for many open-ended services. Like hotels for incidentals. And car washes. If you use you're credit card at a car wash, it usually does a $5 or $10 authorization hold to confirm that the card is valid with sufficient credit limit. Usually shows up as PENDING when checking your account online. Then it gets changed to the real amount (which isn't determined until you finish your service). Sometimes those holds can stay for up to 3 days before they clear.

Sometimes happens getting gas at truck stops too. Before getting the MME, one of our regular road trip gas stops was the Flying J in Richfield UT. They hit us with a $150 authorization hold each time. Seemed excessive, but being a truck stop $150 is more understandable.

 

[Teslaeata]

Well, I live outside of Houston, so electricity is pretty cheap - well, it was until the deep freeze last February completely blew the grid and power markets in Texas... It's still below the national average here, but getting more expensive, the consumers will have to pay for that debacle. Gasoline is cheap too, $2.75 a gallon.

Petrol $8.80 per gallon in UK, enjoy your cheap fuel over there

 

[Mach-Lee]

Last week, we used a ZEF Energy DC Fast charger, for the first time, in Motley Minnesota. The instructions on the DC Charger said; $3 connection fee and 30 cents per minute of charging. I think that means 60 minutes of charging costs about $18 plus $3 or a $21 total. As I recall, the charging unit said we got about 41kwh of juice/power.

However, when I checked my credit card account, ZEF had charged a flat $30 and the transaction was "pending" . I called ZEF to find out: WTF? I was told, they always charge $30 then refund the difference when the transaction "settles". I find this rather dumb. Also, there was no invoice, report, regarding the session details. Just a debit on your card. As such, I disputed the charge on my credit card account, and my credit card company has already refunded the amount. So, ZEF Energy will be screwed until they reconcile the bill and fully explain the charge details.

ZEF Energy does that, when they put a $30 pre-authorization hold on your card it could take until the next business day to process. So if you charged over the weekend it might not properly show up until Tuesday morning. I use the app, you have to add money in your account before you can use it, and there's like a $15 minimum before you can charge.

 

[RWG]

I am not disputing the charges I know I will end up paying. I am disputing the lack of transparency, lousy customer service, and poorly written instructions. As a ( now retired) person who has managed large customer support groups, managed software & web page development, I rate ZEF as "deplorable" in the management/development of their business,. That is just my opinion but I believe that if you are selling something, a product or service, it should work, you should represent is honestly and you should provide support to back up your product. I admit to being "old fashioned" and I admit to getting less tolerant of companies introducing half baked products, with poor support and then focusing on their bottom line, and not the customer. I am hoping that disputing the charges will bring focus to the shortcomings. As it is, the folks I spoke to admit to being "powerless" to making any changes.

Years ago, I had boss you used to say to his team; "Remember, we have no money, we get that from our customers." HIs message was simple and clear. Earn the customers respect , admiration and the customer will gladly pay you.


To: Maquis; Yes you are right, there is probably significant energy loss, heat rejection, from the vehicle on board charger, I neglected to consider that in my calculations. With that in mind, considering the considerable surface area of all the system components 3000 BTUs of heat could be easily distributed.

Regarding Authorization Hold charges; Yes I fully understand the concept and see it during many retail transactions. However, I would offer this observation: If a company is going to take "Authorization Hold" money from its customers, where does the money go? What do they do with it? What are the customers recovery options if the company fails? Far fetched? Consider this scenario; If a company has 1000 charging stations, that get used an average of 2 times per day, and 50% of those transactions have "Authorization Holds" at $30 each session, that equals $30,000 per day Interest on that @4% is $1200 annually. Also, the amount of cash flow, through their bank account annually is $10,950,00. In addition, that amount of financial transaction generates $237,750 dollars of credit card fees, that someone has to pay, normally the merchant.

Personally, I think the "Authorization Hold" concept is a legal scam because if a customer is using a valid credit card, the account is electronically validated instantly. As such the transaction is instantly valid and they will get paid. I say this because I owned 4 restaurants for 15 years, and we processed hundreds of thousands of credit card transactions millions of dollars and never, ever got screwed. An insufficient funds card was rejected on the spot and then the guest had to use a different card or cash. Also, none of use ever have "authorization holds" on credit card purchases at the gas pump for our ICE vehicles. So why the "authorization hold? I suggest it is a way to hoard the customers cash and profit from the transaction.

Another point about the ZEF system. As I understand it you have 2 options to pay to use their system.

Option 1. Download the app. Pre load it with cash, then use that balance when you charge up.

Option 2. Just use your Credit Card, on site, at the charger. They will debit your card $30 and then reconcile the bill later.

In both cases, they are taking your cash, ( hoarding it ) then reconciling later.

 

[dbsb3233]

Regarding Authorization Hold charges; Yes I fully understand the concept and see it during many retail transactions. However, I would offer this observation: If a company is going to take "Authorization Hold" money from its customers, where does the money go?

This is just a misunderstand of what an authorization hold really is. They're not "taking" any money at that point. All the authorization hold does is guarantee that up-to that much money is available when the transaction completes. It ensures to the merchant that the credit card is valid and has that much money available below the credit limit, so that the payment doesn't get declined after the product has been irrevocably dispensed. It's needed for services like EV charging, car washes, and hotel incidentals because they don't know what the final amount will be until the product has already been dispensed.

They're not "holding" any of your money, they're just ensuring it will be there and not be denied when the transaction completes. The hold is just against your credit limit, not transferring any money. The money transfer only takes place when the sale is completed and the final total charged.

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