Check my EV home charging estimate

[nc10]

Trying to compare charging and gas costs for a R1T. My utility offers an interesting experimental EV rate (4.2 cents/kwhr), but only if I charge after 10pm, w high penalties for other times. Looking for input/corrects/comments on my estimates and answers to a couple of questions. Would also be interesting to see comparisons others have made.

Questions:
1. From the R1T manual, it looks like I can program a R1T to only charge after 10pm. Does anyone do this now with an EV, does it cause problems, is it hard to avoid daytime charging?
2. I estimate the efficiency of EV charging to be 85%. Is this a reasonable estimate? Linked one reference below.
3. What should I assume for phantom losses? I assumed 3 kwhr/day, some sources(google, youtube) show similar/higher when security systems are on, others have told me less in another thread here
4. What should I use as an average price for electricity at a public station, used $0.35/kwhr?

Conclusion
At current gas prices, I think I can save $100/month charging at home at night, vs buying gas at today's prices (1000 miles/month).
I'll pay ~$150-$300/year more for charging at pay chargers, vs buying gas, for 3000 miles external charging per year (my guestimate). May use wife's SUV for some long trips instead.


Background
My coop electricity supplier uses this rate structure for my current home billing.

Most recent bill was 1288 kwhrs. Do not own an EV now.

Daily charge $0.78/day X 31 days billed = $24.18
0-200 kwhrs/mnth $0.0863/kwhr $17.26
200-1000 whrs $0.0843/kwhr $67.6
Over 1000 kwhrs $0.0962/kwhr (288 X .0962)= $27.42
Power adjustment charge 1288 X .0092 $11.85

Total bill added up to $148
I've seen adjustments up to 0.012/kwhr.
Almost always over 1000 kwhrs/month.
R1T charging costs will be at the "over 1000 kwhr rate", $0.092 + $0.012=$0.104/kwh (worst case adjustment)

I roughtly estimate I will drive a R1T 1000 miles/month that I can "home charge". (Some more travel will require "pay" charging).

EPA efficiency is 48 kwhr per 100 miles,
1000 miles X 48 kwhr/100 miles = 480 kwhrs/month

I "guesstimate" 3 kwhr/day phantom losses (gear guard, etc) = 90 kwhr/month
Looking forward to real world data.

Estimate the charging efficiency to be 85%
(https://www.caranddriver.com/features/a36062942/evs-explained-charging-losses/)

Total monthly electrical usage
(480 kwhr + 90 kwhrs losses) / 0.85 eff = 670 kwhrs

This will cost 670 X $.104 = $69.68/month at my current residential rate. Will cost $28/month if I charge only between 10pm and 6am, and also sign up for an experimental rate plan.

For comparison, my Outback gets ~27 mpg. I used ~37 gal/month, ~~$100/month on gas last pre-covid year ($2.75/gal) but would spend ~$150 now ($4/gal).

My experimental EV rate plan depends on time of day. Requires a 2nd meter w/only a EV charger. Also includes a $200 rebate for a charger.

10pm to 6am $0.042/kwhr
All other hours $0.15 kwhr

Note penalty for daytime charging!


$0.042/kwhr seems really attractive. I think/hope "only" night time charging will be no problem for me. I'll save over $1000/year at current gas prices, if I can avoid daytime charging.

Electricity from stations looks to be more expensive than buying gas, even today. I estimate buying "station" electricity is $.35/kwhr, and would use for 3000 miles travel. This will cost ~ $600 (3000 X 48/100 x 1/0.85). Gas for my outback would be (3000/27) X $4/gal = $444 (or $300 at 2021 prices)

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[SANZC02]

Looking at your numbers you are double counting the charging efficiency.

The 48 kWh per 100 miles is calculated at the charger so it has already taken the charging efficiency into account. The 314 range equates to 42.9 kWh per 100 miles.

 

[nc10]

Looking at your numbers you are double counting the charging efficiency.

Thanks!

 

[MoreTrout]

Also, depending on your delivery window, where you live in SC, and how quickly Rivian can install their charging network, in theory your first year of ownership could be free charging with the one year membership that comes with it. Of course that's temporary, but probably not insignificant. And depending on what the long term monthly membership fees end up being, if it gives you access to free or really cheap charging on their network it might still be part of the calculation in the total cost comparisons. Even without paying for the membership, I would hold out a little hope that we would still get at least a better rate on their network as an owner and much cheaper than the average public charger.

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