# 90 amps for electric car charge!

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• posted on February 15, 2010, 6:50 pm

It's a 90A Circuit Breaker. However, the maximum current for the vehicle is 70A, as set by the duty cycle of the Pilot waveform. At 240v that is 16.8 kw*4 to do a full charge, or 67.2 kw total. At the national average of \$.12 per kw that is about \$8 (\$.04/mile) for a full charge to drive those 200 or so miles. This is about 1/3 the cost to drive an average gas vehicle at 20 MPG and \$2.60 per gallon.

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<%-name%>
• posted on February 15, 2010, 8:37 pm

And again, this is an example of comparing apples to oranges. These electric vehicles are relatively small cars. And they should be compared to similar size fuel efficient cars, not the average gas vehicle. There are lots of car choices getting 30 city, 45 highway or better. The Toyota Prius gets 51 city 48 highway giving a fuel cost of about \$12. Here in the northeast with electric at 17c kwh, and using your above math, the fuel cost on the Prius vs the electric is a wash here.
But I bet the Prius is a far more drivable vehicle, capable of higher sustained highway speeds, etc. and doesn't have the obvious drawbacks for the user that the electric car has.

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<%-name%>
• posted on February 15, 2010, 4:15 pm
snipped-for-privacy@optonline.net wrote:

Interesting choice for comparison since the Prius is a hybrid (partly electric) car. It is likely to include an option to charge the (relatively small) battery off the grid in the not-too-distant future.
From what little I have seen, the Tesla is a sports car - high acceleration, probably better high speed behavior.
--
bud--

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<%-name%>
• posted on February 16, 2010, 3:56 pm

This talk about loads gets one thinking. Since 99% of homes and 100% of new ones here are electrically heated. And as it happens our island wide electrical sytem for a population of some half million persons is not connected to the North American grid. Any new domestic installations for last 30/40 years or more have required 200 amp services. Distribution transformer loadings (with anywhere from 3 to say 8 homes per transformer in suburban areas) must be installed on some sort of diversity. My heating won't be on simultaneously with all my neighbours, eh? I won't be cooking dinner, or taking a shower at exactly the same time etc. And in fact I will never be using all that 200 amps anyway? But if I were to plug in my 90 amp car recharger ...................... ! Hmmm!

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<%-name%>
• posted on February 15, 2010, 9:08 pm
Well I'm getting out my popcorn to sit back and watch the show in California with this. They [California] had a fit with everyone buying those new TV's which use a bit more energy. (Overloading the electric grid.) In California no one wants any new major electric transmission lines built in their backyard.
If quite a few people buy these cars in California, it will be interesting to see what they do when it places a strain on their electric grid. Neighborhood nukes?
Or for that matter if there was a concentration of these new cars in one neighborhood anywhere. Say 3 homes all on the same electric company transformer. Then all 3 homes get electric vehicles, and they all recharge them at 6:00 pm when they get home on a hot summer day, and also have their AC and everything else going full blast???

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<%-name%>
• posted on February 15, 2010, 10:20 pm
On 2/15/2010 4:08 PM, Bill wrote:

Aren't you assuming worst case? I think a lot of diversity will be involved. Many would likely just use a longer term lower current draw charge.

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<%-name%>
• posted on February 16, 2010, 3:13 am
George wrote:

And a lot more people would be going to off peak rates so they don't start to recharge until people are going to bed.

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<%-name%>
• posted on February 16, 2010, 3:45 pm

OK if you have off-peak rates; which make great sense by the way. By spreading the load. Some places in the UK for example they have (or had) heat storage heaters that used electrcity at night at a cheaper rate. The cheap rate switched off early in the morning as people got up, made breakfast, used electric trains and street cars to get to work, factories started up etc.

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<%-name%>
• posted on February 16, 2010, 5:16 am
Bill wrote:

I remember the Toshiba Corporation small reactor project for Alaska. I wonder how it's going?
TDD

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<%-name%>
• posted on February 15, 2010, 10:17 pm
Bill wrote:

The last one is a good example of the law of unintended results.
TDD

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<%-name%>
• posted on February 16, 2010, 1:55 pm

You have a choice. In his hypothetical case of several homes sharing a transformer, you can either design for worst case or ignore it. The latter could very well result in the transformer overloading and the homes being without power. And his point is a very valid one. The existing transformer loads were calculated based on some assumptions of what loads would be in the future and a worst case scenario had to be calculated. I would not be surprised that suddenly having homes where new 70A loads for 4 hours appear could exceed the system design, with his transformer loading being a good example.
As for using a longer term lower current, there are two big problems with that:
1 - The longer it takes to recharge the car, the less attractive these cars become and they become totally excluded from many applications. That's especially true when you compare their operating costs with similar size ICE cars available today, eg hybrids, that have no charging issues.
2 - In today's instant gratification world, I doubt many people are going to want to charge it at less than the maximum. You need to run a new circuit to charge them anyway, so why would you not make it capable of charging at the max? And once you have that 90A circuit, you know people are going to use it. You could discourage this by offpeak pricing. But that gets back to what I said a long time ago, which is that you need to talk about a COMPLETE solution, from energy generation to the point of usage, not just an electric car. Yet, the miracle, clean, green electric car is all the media cares to talk about.

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<%-name%>
• posted on February 16, 2010, 4:00 pm
snipped-for-privacy@optonline.net wrote:

As with any other big addition of power using equipment, you let the power Cc. know what you are doing (By getting a permit?) The transformer problem is then their responsibility. At least that was what I was told when I added a hot tub years ago.

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<%-name%>
• posted on February 16, 2010, 5:01 pm

You're the first residential user that I ever heard of that notified the power company because they were installing a hot tub. In the rest of the residential world, no one is keeping track of what loads get added. You put in a 200amp service and that's the end of the story. If you need more capacity, THEN you call the electric company and upgrade to 300amps.

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<%-name%>
• posted on February 16, 2010, 5:38 pm

It puts me in awe of the power of gasoline when you consider that the equivalent POWER flow through an ordinary filling station hose at the gas station when you fill up your car is measured in MEGAWATTS!!!
Mark

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<%-name%>
• posted on February 16, 2010, 6:25 pm

Right now it's not an even comparison. But I think you'll all agree we're closer to the end of reasonably priced gas than we are from the beginning. No matter how much you think is left it's definitely a finite resource. On the other hand there are all sorts of potential new sources of electricity. Many that are of limited practicality right now have potential to become more practical either because of technology improvements or just volume increase. Most are "green" and do not add to the carbon dioxide load. Like it or not the days of gasoline powered transportation are numbered.

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<%-name%>
• posted on February 17, 2010, 12:28 pm
jamesgangnc wrote:

The SUN is a finite resource!
Just yesterday:
"HOUSTON - ExxonMobil Corp. added two billion barrels of oil equivalent to its proved oil and gas reserves in 2009, or 133 per cent of its production for that year, the largest U.S. oil company said Tuesday..."
That is, Exxon FOUND a third more oil than they recovered.

I agree. If you had asked the average New Yorker in 1910 what would transportation be like in a hundred years, with a population increase of five-fold, he'd have probably wondered a) Where would we get enough horses, and b) What would we do with all the horse shit.
I'm personally rooting for teleportation.

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<%-name%>
• posted on February 17, 2010, 12:26 am
snipped-for-privacy@optonline.net wrote:

So no one you know gets an electrical permit when adding a major circuit?

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<%-name%>
• posted on February 17, 2010, 1:08 am
wrote:

No.

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<%-name%>
• posted on February 17, 2010, 2:50 pm

You get permit for electrical work from the local municipality. They usually charge a fee and send out an inspector to make sure the work is done according to code. What does any of that have to do with your claim that the power company routinely gets notified when you add a large residential load like a hot tub? Please provide a cite for that. I'd also welcome hearing from anyone else here that notified the power company that they were adding a hot tub or similar load. You notify the power company when you need an upgrade in the service capacity to the house.

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<%-name%>
• posted on February 17, 2010, 3:46 pm
snipped-for-privacy@optonline.net wrote:

Just as I said. The power utility told me they need to know about major additions. They said if I added something large, and they did not know, I could be responsible for damage to the transformer. I assumed that they generally got the info from the permit process, since a permit is required for any electrical addition.