Why only ~3.5kW charging on 240V instead of >7kW that EVSE's are designed for?

[sinnombre]

Here is the problem . Many of us early Volt lovers are perfectly satisfied with a 12 amp , 10 -12 hour charge or a 6 hour charge to top off the battery . However , if GM increases the battery usage to 12 kWh or more , like I think they will in the future , it will take 14 hours to charge . I don't think Los Angeles Barbie or New York Ken will go for that . 240 V home charging is the future . Their first question is : How long does it take to charge ?

[petefoss]

What would accommodate most customers would be an option for a second charger to be installed, either as factory installed, dealer installed, or even after market. Inverters run about $0.50 per watt retail, so maybe $2000 for a 4KW upgrade for 7.5 KW total.

Don't forget the cost to engineer both chargers into the vehicle, stock and track two versions, duplicate many of the validation tests, etc. etc. etc. I'm not saying we can't or won't do it. But the decision to offer multiple options is not simple. There are lots of hidden costs.

[Ladogaboy]

Don't forget the cost to engineer both chargers into the vehicle, stock and track two versions, duplicate many of the validation tests, etc. etc. etc. I'm not saying we can't or won't do it. But the decision to offer multiple options is not simple. There are lots of hidden costs.

I think that it might be easier to just upgrade the existing internal inverter. You'd still need to deal with the software upgrades and validation tests, but it seems to me that it would be easier than trying to just double up inverters. Isn't there some Moore guy who said something about technology doubling, blah, blah, blah? Anyway, I'd think that, at some point, a 3.3kW inverter could be replaced with a 6.6kW that takes up roughly the same amount of space.

[DCFusor]

Interestingly, GM has cut the default charge rate on the '13's to the lower setting (for L1 anyway), and forces you now to set it up every single time.

I think there are lawyers involved here, what you can do technologically or business wise isn't the real issue. Burn down some houses, you have trouble - even if it was the customer's fault (hard to prove). As it turns out, though, going to 30 amp from 15 gets you into a more complex design due to the limits of the common/inexpensive semiconductors they're probably using. Try and find a good, inexpensive 30 amp FET for 500-600v if you know that kind of thing.

In answer to the guy above - the open source project (as far as I know) doesn't sell kits. You just buy all the parts off the normal distributers and roll your own. If you don't have a clue about how to go about that, it's likely going to be past you to pull it off, even though the thing is simple (to a 50 years experience EE, that is).

[Chevrolet Customer Svc]

Everyone,

I thought I would share the following on this important topic from the GM Director of Advanced Vehicle Commercialization Policy, Britta Gross:

"Nice string of comments here going back and forth on the pros and cons of
faster charging - bottom line, faster charging is definitely a real
nice-to-have for some customers, but it comes with some cost, vehicle
packaging challenges, and more vehicle weight. One other important aspect
that hasn't been mentioned here, but that we considered early on was the
impact to the grid. We were determined to design a vehicle that didn't
require any special charging infrastructure and that didn't introduce new
energy/grid problems. That meant the vehicle had to be able to charge
overnight using a normal household outlet (1.2kW charge rate - same load
as most hair dryers). And for those who preferred a faster 4-hour charge
we felt the 3.3 kW charge rate was also reasonable (this is about 1/2 an
electric clothes dryer load, but running for 4 hours). We asked EPRI (the
Electric Power Research Institute) and our numerous utility partners
around the country what they thought about these proposed load levels -
and they broadly felt these were acceptable load levels and would be
relatively "invisible" to the grid. After a year and a half of Volt roll
out, utilities broadly confirm that 3.3 kW charging has not introduced any
significant issues. However, higher charge rates in homes, like 6.6kW and
higher, will drive more issues for more consumers (this load will now
overshadow most loads in a home) - and this will result in added costs for
consumers and utilities (e.g. if a service upgrade has to be done for the
home, and if this service upgrade now drives the need to add local
transformer capacity). Bottom line, as the charge rate capability of
vehicles increases, there will be an increase in issues and the costs
involved for a growing number of customers. This doesn't mean we won't go
there, but it does mean that there's an important down side that is worth
considering."

- Britta

[DonC]

Thanks Trevor for passing Britt's comments on. I have a two word response for her: Wireless charging!

I'd take 3.3 kW wireless over 6.6 kW plug-in charging any day. Given the Volt's battery size, and even the Leaf's battery size for that matter, 6.6 kW charging is marginally important. But I would love just to pull into the driveway and never worry about remembering to plug it. Plugging in isn't a big issue but NOT having to plug in is just one less thing to worry about.

Britta's comments are no doubt accurate and well intended but we're self-centered consumers. Grid problems are not our problem and the utility needs to make it work! LOL (That's the reality of it). But the issue she brings up is real. I live near the coast where it's cool, and most people so not have AC. When more people started putting in AC we had plenty of transformers blow. These higher charge rates pose the same issue. The solution to this from the utility perspective is of course "demand charges". Why should it have to spend megabucks to upgrade the system, making everyone pay, because a few people want to use charge their EV as fast as possible. The solution to this of course is to incorporate demand chargers into the rate structure, which chargers a lot for a high charge rate, and I don't think anyone wants to go down that path.

[cnicholson]

Ditto on thanks to Trevor/Britta. Musing is fun, but reality is also interesting.

@DonC: As a guy who loves technology for technology's sake, I LOVE the idea of wireless charging, but I see a few real world challenges there as well: unless there is a universal standard soon, we already have legacy issues that will be hard to shake. Realistically, will OEM's be able to have ONLY wireless charging and skip the wired port? If not, then it would be an incremental cost.

Also, I am pretty clueless here, but wouldn't induction charging require pretty precise alignment and proximity requirements? Is that compatible with a "portable" charging mat that can be tossed around different spots in the garage and thrown in the trunk?

Now now, my vote would still be for faster charging. Forget about engineering and the grid: when consumers hear that the 2013 Volt takes 12+ hours to charge, that's a barrier to buying. Think marketing. "Optional 3-4 hours quick charger" helps, but "20-25 miles of range in about an hour" starts to make charging time a non-issue....

Finally, back to the real grid issues, I say lets get a better return on the SmartMeter investment and implement staggered pricing for >3kW charging during peak hours. Why not? If the pricing structure is geared toward balancing load and not maximizing profit (a big "if," I realize) then we should all prefer that, right?

[DonC]

From the demos it doesn't seem like even the current wireless charging units need precise positioning but the guidance would seem to make this not such a big deal. http://www.youtube.com/watch?v=l0MYG...4&feature=plcp As for costs, I'm thinking 6.6 kW or wireless will be similar. As Britta points out, the Volt will have to support 120V 8A charging at the low end. Having the charger also support 3.3 kW and 6.6 kW will add complexity, cost, and weight.

I'm also not sure how big a benefit 6.6 kW charging is. Of course faster is better, but 20 miles in an hour will likely not impress anyone. In my Volt I can get 300 miles in ten minutes IF I fill it with gas. Twenty miles per hour is faster and better than ten miles but both are horribly slow and impractical if I need to go anywhere. Seems that once you get past minutes it doesn't matter if it takes four hours or two. I'd need to do it when the car is sitting.

Just a note on pricing. Peak pricing differs from demand chargers. Peak pricing is designed to time shift demand. Demand chargers are designed to discourage high charging. The problem with higher wattage EV chargers isn't that they'd be used at peak hours, it's that they would require an upgrade to the grid, so the remedy would be demand charges.

[Ladogaboy]

The biggest benefit of 6.6 kW charging is on the road. Now that Blink and ChargePoint are charging on a per time (not per usage) basis, it becomes cost ineffective to charge the Volt away from home. A $2/hr charge wouldn't be as big of a deal if it meant that we could be full capacity in two hours; we would be at a break-even point with gasoline.

And in terms of affecting the grid, limiting the 6.6 kW (if people wired their homes for it) to off peak hours would mean that the car would have little impact on the grid load.

[bjhorton2005]

Exactly! Due to cost of charging being per hour, it's just dumb and many times not worth it to plug in for pay.

There have been many times I sit waiting for my car to charge before heading back into town. Many long trips where I stop to eat and instead of filling my battery up to help drive the mpg for the trip up, I barely get any at all.

The battery is obviously able to handle the power. In mountain mode, I think it is receiving more than 7.2kw charge.

I for one, am on the lookout. The minute an aftermarket solution hits the market, I'm going for it. I just know it needs to somehow integrate with the Volt, because it will certainly require the thermal management.