I want to pay my neighbor back! How can I measure electricity usage?

SageBrush said:

Back to paying for electricity ...
Metering is a PITA. I would off to pay the local rate for a kWh every 3 miles on the odometer and call it a day. Keep a log of your odometer and update/pay once a month.

If OP is an aggressive, lousy driver than up the payment to a kWh every 2.5 miles.

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This seems like the most sensible choice to me. No hardware necessary. It's quite difficult to obtain worse efficiency than 3 M/kWh over any appreciable timeframe, so it errs somewhat in favor of the neighbor, but that's probably a good thing and any inaccuracy is more than made up for by the simplicity.

I guess nobody took the time to look at the that Item I posted?.....which is perfect for this situation?

The OP will look at is surely, which is all that really matters since it's him/her we're trying to help. You have to admit though, the meter you linked to is pretty expensive.

alozzy said:

The OP will look at is surely, which is all that really matters since it's him/her we're trying to help. You have to admit though, the meter you linked to is pretty expensive.

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yep...but it will not start a fire LOL

Nubo said:

It's quite difficult to obtain worse efficiency than 3 M/kWh over any appreciable timeframe, so it errs somewhat in favor of the neighbor

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I was including ~ 20% charging losses, so paying by 333 Wh/mile presumes 266 Wh/mile driving consumption.

Learjet said:

alozzy said:

The OP will look at is surely, which is all that really matters since it's him/her we're trying to help. You have to admit though, the meter you linked to is pretty expensive.

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yep...but it will not start a fire LOL

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Fair enough, but Sagebrush's suggestion to simply track mileage and divide that number by three, to arrive at kWhs, is simple and if anything favors the neighbor (a good thing). Or, just pay the neighbor $40 a month which is likely more than fair.

The KISS principal applies here

alozzy said:

The KISS principal applies here

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Yes indeed, including a Thank You present to the neighbor.

alozzy said:

Learjet said:

alozzy said:

The OP will look at is surely, which is all that really matters since it's him/her we're trying to help. You have to admit though, the meter you linked to is pretty expensive.

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yep...but it will not start a fire LOL

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Fair enough, but Sagebrush's suggestion to simply track mileage and divide that number by three, to arrive at kWhs, is simple and if anything favors the neighbor (a good thing). Or, just pay the neighbor $40 a month which is likely more than fair.

The KISS principal applies here

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very true

FWIW, my 2019 SL Plus averaged 2.51 miles/kWh wall-to-wheels over the last 5 charge cycles with high ambient temperatures and heavy air conditioning use while the dashboard efficiency ranged from 2.8 to 3.1 miles/kWh. These charge cycles were using my AeroVironment 240V, 30A EVSE. Since net charging efficiency is lower on 120 volts and you don't want to underpay your neighbor, it might be prudent to use 2.5 miles/kWh when calculating the energy consumption from odometer readings.

I have been using a revenue accuracy meter in the feeder circuit for the EVSE for a long time. All three of my LEAF's display dashboard efficiencies significantly higher than the actual wall-to-wheels efficiency (was typically about 0.5 mile/kWh difference for the 2011 and 2015 and is a little less difference for the 2019).

SageBrush said:

Nubo said:

It's quite difficult to obtain worse efficiency than 3 M/kWh over any appreciable timeframe, so it errs somewhat in favor of the neighbor

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I was including ~ 20% charging losses, so paying by 333 Wh/mile presumes 266 Wh/mile driving consumption.

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Good point.

GerryAZ said:

you don't want to underpay your neighbor,

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Along these lines, find out if the utility has peak hours and avoid or pay for them. You can also find out when the grid is cleanest. The car has a delayed charging timer that works (in my experience, anyway.)

SageBrush said:

GerryAZ said:

you don't want to underpay your neighbor,

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Along these lines, find out if the utility has peak hours and avoid or pay for them. You can also find out when the grid is cleanest. The car has a delayed charging timer that works (in my experience, anyway.)

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Good point--with the rate structure I have at home, one charge at 120 volts on peak would increase my monthly demand charge by about $24.00 while the energy cost would only be about $0.10 per kWh so a total of $29.00 for 50 kWh. At 240 volts, the demand charge increase would be about $105.60 while the energy cost would still be $0.10 per kWh so the total for 50 kWh would be $110.60 on peak. The off-peak charging cost in either case would be about $0.06 per kWh for a total of $3.00 for 50 kWh. Needless to say, I NEVER charge at home during on peak hours! I have the charge timers in the car programmed to avoid charging on peak.

^^ ~ $30/kW demand charge ?

GerryAZ said:

Good point--with the rate structure I have at home, one charge at 120 volts on peak would increase my monthly demand charge by about $24.00 while the energy cost would only be about $0.10 per kWh so a total of $29.00 for 50 kWh.

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The demand charge would only apply if was during the time of highest demand for the month. Might be able to avoid with timer, correct?

WetEV said:

GerryAZ said:

Good point--with the rate structure I have at home, one charge at 120 volts on peak would increase my monthly demand charge by about $24.00 while the energy cost would only be about $0.10 per kWh so a total of $29.00 for 50 kWh.

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The demand charge would only apply if was during the time of highest demand for the month. Might be able to avoid with timer, correct?

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Would only apply if the charging set a new highest demand for the month *during the peak period.*

SageBrush said:

WetEV said:

GerryAZ said:

Good point--with the rate structure I have at home, one charge at 120 volts on peak would increase my monthly demand charge by about $24.00 while the energy cost would only be about $0.10 per kWh so a total of $29.00 for 50 kWh.

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The demand charge would only apply if was during the time of highest demand for the month. Might be able to avoid with timer, correct?

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Would only apply if the charging set a new highest demand for the month *during the peak period.*

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Read carefully.

I was helping someone with demand charges, and there were two different demand charges, one on peak and one off peak.

He was trying to charge overnight, and suddently had a much larger than expected on peak demand charge.

Why? Clock for demand charges was standard time. Car timer was on daylight time. Oh...

WetEV said:

Why? Clock for demand charges was standard time. Car timer was on daylight time. Oh...

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That little gotcha may come up twice a year.

My rate example was based upon the 1-hour peak demand being increased by the demand of the car charging. It would be about 1.5 kW for 120-volt charging and 6.6 kW for 240-volt charging. The demand charge is about $16.00 per kW. I have a demand controller in the house to minimize peak demand so charging on peak would increase the demand by 1.5 or 6.6 kW. There is no demand charge for off-peak power consumption so I have the car charge timers programmed to prevent inadvertent charging during peak hours. Of course, the cost for the second charge on peak during the month would just be the energy cost or about $5.00--it is the one-time charge for the month that creates the large expense.

In actuality, I could not charge the car entirely on peak now because the peak hours have changed several times in the last few years. Peak hours were 9:00 AM to 9:00 PM Monday through Friday for many years (with lower energy costs per kWh). The peak hours were changed to 3:00 PM to 8:00 PM Monday through Friday 2 or 3 years ago and they were changed to 4:00 PM to 7:00 PM Monday through Friday a couple months ago. The energy costs for both on peak and off peak were increased significantly each time when the peak hours were reduced while the demand charge remained about the same. The effects of these changes are that my total house bill went down because most of the air conditioning load is now off peak, but car charging costs went up because the car was always charged only off peak. My demand controller now keeps the peak demand down to less than 0.5 kW whereas it would be 3 to 4 kW during the summer on the 9:00 AM to 9:00 PM rate to keep the house cool.