Charging batteries at home.. HEAVY DRAIN!

I just heard that charging the car using 220VAC, over an 8-hour period, uses as much electricity that a typical home uses in 24 hours. Haven't done the math, and yes you'd save money on gas, but talk about hi electric bills... Power companies should give owners a break on their bills.

Solar panels anyone??

Serious? That's crazy. I wonder how many Nissan Leafs it will take to require so much power that electricity rates start going WAY up!

Do you have a link to an article or anything that talks about it?

Solar panels for sure are the way to go, unless you have a lot of kids and you can hook them up to a large hamster wheel :lol:

Hey, don't panic, guys. Electricity costs a lot less than gasoline. You should be able to go about five miles on one kilowatt hour (kWh) of electricity, and that will probably cost you less than 10 cents. That's 50 miles for $1.00, or 150 MPG with gas at $3.00. Is anybody getting gas mileage like that?

Sure, IF you drive 100 miles every day your Leaf is going to be very hungry at night, and IF you don't use much electricity now that might double your use, but unless you deliver pizzas all day, seven days a week, I don't think you are going to drive 100 miles every day. A show of hands, please. How many of you drive your current car more than 36,000 miles per year?

... That's what I thought.

Actually, quite a few of the RAV4-EV owners drive over 80 miles per day. It also has about a 100 mile range.

But most electric utilties DO offer discounted rates, both "super-off-peak" and "EV" rates.

My RAV4-EV was on a separate meter, so it did not raise my "household" usage at all, and let me see exactly what electricity was costing me versus my mileage.

5 miles per kWh wall-to-wheel is probably a bit optimistic. That might be right for the number from the battery to the wheel, but there are charging losses and other overhead that uses some of the electricity you pull from the wall. Both our Tesla Roadster and RAV4-EV get about 0.320 kWh/mile. Our electricity cost is $0.11/kWh, so that comes out to about 30 miles per dollar of electricity, or about 90 miles for the cost of a gallon of gas.

In short, you don't have to worry about how much your electricity bill goes up, because that will be more than offset by the money you save from not buying gasoline.

If you're worried about being able to pay your electric bill, every time you do a charge put money in a jar equal to the cost of gas to travel the distance you drove since the last charge. For example, if your gas-burner gets 25 mpg and gas is $3/gallon, that's $12 per 100 miles of driving.

Do that all month, then send one third of it to the electric utility and use the rest to throw a party. The more you drive, the bigger the party.

If you're worried about the cost of replacing the battery pack in 5 to 10 years, then instead of throwing a party every month on the extra cash from the jar, deposit it in a savings account. Throw in $30 every three months for the oil change you don't have to do, plus another $100/year for engine engine/muffler/transmission maintenance you don't have. Add a little in interest and you'll have over $10,000 after eight years of driving 12,000 miles per year, which should be more than enough to buy a replacement battery pack. The electric motor and gearbox should last much longer than an engine and transmission, that should cover all of your drive train costs for 8 years, with enough left over for a nice party.

I've also read a full charge would cost between $1.50 and $3.00 depending on how much you pay per kilowatt. I figured I will pay about $2.00 because our electricity rates are fairly low. That is 100 miles for $2.00. I certainly can live with that. No need for solar panels right now.

Here, in southern CA, the "base" rate (currently, fir the first 336 kWh of usage) is about $0.13 per kWh (I call one kWh an "edie", after Thomas Edison), but the base allottment is easily used, even with "little" use.

Tier 2 (the next 101 kWh) is about $0.15 per edie, but this quantity is also easily used.

Tier 3 (the next 235 edies) is about $0.28 per edie, and air-conditining (or EV charging) will easily use this up.

Tier 4 (beyond the Tier 3 usage) is apparently $0.30 per kWh - easy to reach with any significant EV charging.

Thus, 24 edie at $0.30 is just over $7, for the "full tank".
So, I put in a 7kW PV solar system.

According to census data, the average car goes about 32 miles per day. At ~250Wh/mi pack-to-wheels and 90% wall-to-pack efficiency, that's 8.9kWh. US residential rates average just over 10 cents per kilowatt hour (sorry CA and NY, you get ripped off!). So that's about 90 cents per day for the average car in the US (~$27/mo).

One mistake people often make while talking about charging is the assumption that every charge is a full charge. You see it both in discussions of how much energy is needed to charge at night, as well as discussions of "What if I don't have enough energy to make it home". If you're 10 miles short of making it home, you don't need to get a full charge; you just need 15-20 miles worth of charge.

You would definitely want to go on a "Time of Use" rate with your EV to get the best price for your charges.

In San Diego, SDG&E has the EV-TOU2 rate already in place and it is quite attractive vs. the tiered "Domestic Rate" that we are on now. Charging the car from midnight to 5am during the "Super Off Peak" timeframe is the cheapest, and if I remember correctly that price will be 13 cents per kwh or thereabouts.

That seems like the only way to go for charging the Leaf...

Randy, not to disappoint you... but this will. SDG&E charges 13 cents for electricity, but then they charge you another 16 cents to deliver it to you. Frustrating. I had to put up with it for 5 years. Total cost is 29 cents per kWh including taxes and whatnot.

Still only $30 per month, but I only drove a little over 5,000 miles per year.

Yes, the billing structure for TOU rates for CA utilities are a major PIA. Not to mention confusing as hell to figure out. Why can't they put the kWh rate (transmission + electricity included) in one simple table using current rates?

The Super Off Peak rates are more than the first two baseline tier rates!

The only time TOU makes sense is if you can generate electricity (for residential users, that means solar panels) in which case if you do it right it can be cheaper to use TOU metering.

The only other time it may make sense is if you use a lot of electricity (way over baseline) and use the vast majority of that electricity during off-peak hours.

Not only that, but if you want an extra EV-TOU meter, you have to rent it from SDG&E. Not a lot, $3.50, but still, what the ...?

I actually never could decide if using my regular house meter would have been less expensive. We are normally way below baseline and the RAV4-EV wouldn't have put us over, or not by much. Then I could have charged any time, day or night, instead of having to be sure I only charged Midnight to 6AM.

And they did not switch daylight savings hours when everyone else did either, so to be safe, I could really only charge between 1AM and 5AM.

I love SDG&E :lol:

Hi Dav,
I'm not sure if you're on the relatively new EV-TOU2 rate, but I have some good info about it. I think it's cheaper than what you were quoting. The Super off-peak rate that I was talking about is about 8.5 cents for the energy, and the total including all the fees is 13.7 cents per kwh. I thought that was pretty good. So here is a summary of what I got...

EV-TOU2 in summer 5/1-10/31:

12am-5am (Super off-peak): 13.7 cents total
5am-noon and 6pm - midnight (Off Peak): 16.7 cents total
noon - 6pm (Peak): 28.9 cents total

Domestic Rate (DR) in summer 5/1-10/31:

Baseline: 12.87 cents total
101%-130% of Baseline 14.88 cents total
131%-200% of baseline 31.96 cents total
Above 200% of baseline 33.96 cents total

How does that measure up to the rate that you're familiar with?

Thanks, Randy. I really shouldn't have posted until I went and got a copy of my utility bill. I'm glad it is better than I made it sound.

Still, SDG&E could make it easy, and for their own purposes make it totally indecipherable to any layman.

KarenRei said:

According to census data, the average car goes about 32 miles per day. At ~250Wh/mi pack-to-wheels and 90% wall-to-pack efficiency, that's 8.9kWh. US residential rates average just over 10 cents per kilowatt hour (sorry CA and NY, you get ripped off!). So that's about 90 cents per day for the average car in the US (~$27/mo).

One mistake people often make while talking about charging is the assumption that every charge is a full charge. You see it both in discussions of how much energy is needed to charge at night, as well as discussions of "What if I don't have enough energy to make it home". If you're 10 miles short of making it home, you don't need to get a full charge; you just need 15-20 miles worth of charge.

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I've already figured my electric charging costs (presently I'm paying about $40/mo. for cng @$1.60 gge for 1000 mi. [averaging 42 mpg]). With the electric car it will be ZERO...LOL...because my spouse pays our electric bill, and I pay our cell phone bill. In December, our off-peak rate is only 5.8c kwh so I'm figuring one charge, half full, to be around $ .70. I'm pretty excited that I will be able to charge in the garage (presently I drive 56 mi. roundtrip to get fuel (cng) about every two weeks) and it will be soooo inexpensive. We hope to have pv's on the roof to charge it before I get the car (not to save so much money, but to be true zero emissions), hopefully in Dec., 2010.

According to the PG&E website for EV owners the TOU rates can be applied either to the whole house or just to the charging station, subject to local ordinances permitting dual metering. I once saw a spreadsheet that calculated that our entire electric bill would be lower with the whole house on that schedule, even including an EV that travels only the small mileage that I would, than it is currently, but I don't know if I trust it. I figure other PG&E customers (e.g. Sacramento) will get the chance to buy before I do and I hope they post their experiences and choices here for us followers to see so we can decide how to go on this.

Though I had the TOU meter installed with my solar installation, I would recommend this rate structure to anybody, as it should be relatively easier to burn more power and recharge the EV in the evening....The SoCal/ SW folks here might have to go a bit easy on the AC in peak hours.

Rat said:

I figure other PG&E customers (e.g. Sacramento) will get the chance to buy before I do and I hope they post their experiences and choices here for us followers to see so we can decide how to go on this.

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Well, Sacramento may not be a good example, because they don't use PG&E. I don't know what kind of special rates SMUD has or will have for EVs. But, like you, "Rat", I'm in the Silicon Valley area and, unless I'm missing something, my PG&E E9 rate will be only five to six cents/kWh if I can stay under 130% of baseline. One way to do that is, as you point out, to have separate metering for the Leaf, but then you have to pay a double meter charge. I've already implemented the other way, which is to have solar panels on the roof.

But, yeah, I'd sure love to hear some good news about when we can get a Leaf. We're a loooong way from San Diego (450 to 500 miles, to be specific).

KarenRei said:

According to census data, the average car goes about 32 miles per day.

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