Your math may reflect the most inefficient home-built vehicle, based on low-cost components such as a DC motor and lead-acid based batteries. However an OEM would produce nothing like this and use lithium based battery technology and a more efficient AC motor.

An example of this would be the Tesla. IIRC the Tesla achieves roughly 225 watts per mile. Your math assumes that EVERYONE drives 65 miles per day. IF this were true, this would only be 14,625 watts consumed and not 25,000 or more like you suggest. Take this with a 110v (commonly outputs 120v) 15amp circuit which translates to a supply of 1800 watts per hour. This means that a simple outlet could recharge the pack in 8.2 hours. Of course as you mentioned, the charging efficiency is not 100%, nor is converting that to mechanical energy 100% either, but not to the tune of taking 10 – 12 hours to recharge. EVEN IF that were the case, I get home at 7pm and if I plugged in to charge until I leave for work at 8am the next day, I’ve got 13 hours of charging completed which falls realistically within your worst-case scenario. I am an example of a cummuter who spends over an hour commuting each day, however it consists of no more than 25 miles total with 48 traffic lights to contend with. BWT, the regenerative braking is far more than a 10% return. It is more around 60%, of course depending on how much you make use of that with your driving style. WHEN EV’s become common, there will be charging stations you would be able to connect to while at work to keep your energy level from becoming depleted.

If you would like even better evidence, I personally know an individual with a Scion eBOX (xB converted to electric by AC Propulsion) who is capable of a 120 range within city driving and performs a recharge from a standard outlet within 13 hours. Anyone like himself with an electric vehicle would be interested in installing a 240v 50amp circuit in their garage which allows him to perform the same recharge within 3 hours.

If your worried about pulling too much from the grid, the AC Propulsion controller allows him to dial-in the amount of load it pulls from the circuit it is connected to.

If you want to go beyond that, the AC Propulsion controller has existing technology that allows a smart metering system from the power company to control remotely the amount of current his charging system is pulling on the fly, in real-time. The system would be capable of communicating to the charger to variably reduce the amount of charging current, halt the charging, and if needed reverse the current and draw from the battery pack. With enough vehicles like this on a grid, if the load within the grid became too high they could simply request the from the thousands of BMS (Battery Mgmt System) units that are near full capacity to momentarily discharge back into the grid to function as a capacitor/buffer device on the electrical grid. Since energy cannot be stored in the form of alternating current and only in the form of D/C, these controllers allow the D/C energy within the vehicle to be converted on the fly into A/C energy since no power company has this ability to handle sudden loads like this. This would be a major benefit to any power company.

This technology is not even that high-tech. With the internet, let alone basic radio channels that could be tuned into, this could be accomplished easily. Many communities have radio channels that are tied into local weather stations and can tell your water sprinkler system when to water the lawn. In south Florida (at least) FPL has had ON-CALL BOXES installed into nearly all residential for about 15 years now. These boxes are wired into high-load appliances such as water heaters, sprinkler pumps, etc. and FPL can remotely choose to turn these systems off unit-by-unit if the load on the grid is becoming to high, permitting relief to the grid when needed.

~Scott

You seem to think technology and knowledge are static and the rules for today are the way it will always be. I charge my electric car very nicely with solar panels – technology still developing and not even thought of just a few years ago. What is your answer-find more oil?

OK, so maybe you go for a 3-Phase plug 240V, 30 amp. That would reduce the charge time to about 5 hours. If you had a charge circuit at your workplace, you could reduce the overnight charge time further. These are not insurmountable problems.

I haven’t done a survey of how happy electricity utility companies are with the idea of lots of people charging their cars overnight, but I’m a little worried that the math may be grossly underestimated.

It takes about 20kW of power to run a small car on a highway at 65MPH, for an hour. Stop and go traffic (city driving) is typically about 25% (to 35%) worse than that (Don’t bother betting on regenerative breaking to save you – you get at most 10% of your energy back into the batteries).
According to the US census, the national average American commute is about 25 minutes each way. Let’s just say 60 minutes per day total, for convenience sake.

That’s 25 kW of power taken every day per electric-only car that needs to be charged each night.

At 80% charge efficiency (you need more electrons to charge a battery than you can extract from it later) and 90% AC-DC power conversion, you’ll need 33kW of power each night to charge your car.

problem 1: Given a 110v, 15A circuit, it will take 20 hours to recharge your car if you can run your 110v, 15A circuit right at the max. Even if you sell the idea as “It’s cheap!” as in your example, it just doesn’t work – you’d need to charge in 10-12 hours or less, or your car won’t be ready in the morning.

Problem 2: Especially in colder climates where electric heating is still in use, don’t expect that an extra 33kW for a 10 hour period in every household for every weeknight will not require major upgrades to the power grid. Taking a base example, the average US house draws just over 10,000 kW hours in a YEAR. Given this new proposed electric car demand, just for weekdays (assuming people stay home on weekends, or take public transit) this is a 66% power demand increase, on average. If you’re a power company, and need to plan for peak and not average, the numbers look considerably more scary. So, I don’t for a second believe that power grid infrastructure will just absorb this without some major upgrades, even in this “best-case” scenario where I assume your average American only uses a car 5 hours per week.

A: The improvement in batteries’ energy density runs on a fairly steady curve, and so does the decline in cost per kWh. Think of it as a battery version of Moore’s Law. I couldn’t tell you off the top of my head what the numbers are, but they’re pretty well known in the industry.

Can you follow up on this? I would be interested to know what the answer is. It may be well known in the industry, but it isn’t common knowledge outside it (unlike Moore’s Law).

Thanks.