Comments on: Mercedes-Benz SLS AMG Electric Supercar — More Details Revealed

By: Otis11

Otis11 — Tue, 12 Mar 2013 17:49:00 +0000

Well, if those price differences are actually seen by the end user, yes it would make sense to use the car in this way, but it would actually make better sense just to get a battery pack for your home. The Home battery pack doesn’t have to have as high of charge density and so the cycling doesn’t matter as much as in a car.

So while I can see some people wanting to do it, it will never be the best option given current battery technology.

By: Justin R Pearce

Justin R Pearce — Tue, 12 Mar 2013 16:11:00 +0000

the units of kW already include a time dimension, so you get just a usage of 0.25 kW or 0.25kWh/h

By: Ronald Brakels

Ronald Brakels — Sun, 10 Mar 2013 10:03:00 +0000

Sometimes the spot price of electricity goes over $10 a kilowatt-hour here. That’s more than enough to pay for battery pack wear and tear. A price difference of 30 cents between what electricity is bought and sold for should be enough to pay for itself, although one might want to go for a higher figure if one is pessimistic about how much it will cost to replace a car battery pack in the future.

By: Otis11

Otis11 — Fri, 08 Mar 2013 19:12:00 +0000

About the house powering option – couldn’t hurt, but it’s not really that useful. We have a lot of business people talking about how electric cars could stabilize electric grids, and while they could do this by actively controlling their power demand, they will not (or should not anyway) be used to supply power to the grid unless battery technology changes significantly. From the perspective of the Engineers who design these systems – they simply are not designed to handle that yet.

“Good of those in the 0.01% who want to drive an electric car. ” => Sounds like very few people want to drive electric cars. I understand what you meant, but consider rewording.

By: JustSaying

JustSaying — Thu, 07 Mar 2013 16:32:00 +0000

I’ve also wonder anout using current EVs as grid backup. Time to they take extra power when there is too much yes. But with “only” 2000 cycles I don’t want to loose the range. Now when were are talking 10k-30k cycles, without real drop off, then grid backup is there. Now it is more backout for when the grid is gone.

By: Jouni Valkonen

Jouni Valkonen — Thu, 07 Mar 2013 15:03:00 +0000

perhaps you should consider what is the price per kWh and estimated cycle life of the battery pack. Then you can calculate what is estimated price of electricity per kWh that is fed from vehicle into grid.

You must remember that every time you are discharging EV battery, it reduces the value of EV, because it reduces the range. Do you really think that reducing range is worthy?

The price of vehicle to grid electricity when using Tesla’s NCA batteries (life time around 2000 cycles) is something in order of $500 per MWh + the annoying range and value reduction of EV. At that price point, perhaps you would rather want to put into operation few extra coal plants to provide intermittent electricity!

What EVs are good for is that Lithium batteries like that the charge is maintained as constant as possible at around 40 % of capacity. Therefore for daily commutes capacity range 20–40 % is more than enough. And only when there is plenty of wind and solar available, battery can be charged to the 90 % level that is maximum recommended charge level. Full charge and full discharge reduces the cycle life of EV batteries.

By: Pete Stiles

Pete Stiles — Thu, 07 Mar 2013 13:01:00 +0000

My annual average is 7 KwH per 24 hours so roughly 1/4 Kw per hour

By: Justin R Pearce

Justin R Pearce — Thu, 07 Mar 2013 09:45:00 +0000

Maybe not number of houses, but number of hours would be a more descriptive energy unit since we are all inherently selfish and only want to think about our own house.
By the way, where did you get the figure of 3kW per household from? I know my house is far below that, and according to “http://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3″ the figure for American houses is about 1.3kW