Will energy usage to charge vary with voltage, charger used?

[EVDRIVER]

Then again, I still want to see the 3.3 throttle raised to 6.6 at no cost to the initial owners, and ASAP (or earlier ... like at delivery of the first LEAF).

If they're going to increase it, I'd like to see them go all the way to 7.2kW so we can use all of the 30A that a typical L2 EVSE will supply. While this would be overkill for most overnight home charging (I'm planning to use a 16A Leviton here at home), it would be great for destination charging at public charge points. For instance, if I drive 60 miles to a destination (say a store) with a charger (at freeway speed), I may want to replenish my LEAF's battery in an hour or less so that I can make the trip home without range anxiety. 6.6 kW would take half the time of 3.3 kW, and 7.2 kW would be even better! If I could pick up 7.2 kWh in an hour, that might translate to 25-30 extra miles of range.

I have been saying this for some time, in all of my years of charging at 7.2kw or higher I have found it makes a huge difference in the utility of a vehicle. Not to mention the benefit for fixed-rate public parking where you get free charging.

 

[Coffee_Slurry]

The one person I know who had an EV1 for three years agrees with you, EVDriver.

He explained that, from his experience, charge rate is actually far more important to convenience than range.

 

[johnr]

I just recently read two test drive reports for the Volt that stated that they measured over 13 kWh used to charge the 9 or 10 kWh of usable pack. I'm assuming that these journalists used L1 charging from a home or office 110 V outlet.

Do you think that this is expectable charging losses at L1, or that the Volt is taking on more kWh than these writers knew about, or something else is going on?

http://www.insideline.com/chevrolet/volt/2011/2011-chevrolet-volt-full-test-and-video.html

http://www.caranddriver.com/reviews/car/10q4/2011_chevrolet_volt_full_test-road_test

That sounds reasonable. No charger is 100% efficient, and no battery is 100% efficient at absorbing energy. So getting 80% of the energy you put it is not unreasonable. Though I would assume the Leaf's internal charger is optimized for maximum efficiency so I would expect closer to 90%.

 

[planet4ever]

I just recently read two test drive reports for the Volt that stated that they measured over 13 kWh used to charge the 9 or 10 kWh of usable pack.

That sounds reasonable. No charger is 100% efficient, and no battery is 100% efficient at absorbing energy. So getting 80% of the energy you put it is not unreasonable. Though I would assume the Leaf's internal charger is optimized for maximum efficiency so I would expect closer to 90%.

"over 13kWh" to charge maybe not even 10kWh is more like 75%, which I find hard to believe. Even 80% sounds pretty unreasonable to me. Given the general negative bias of the article I would suspect a bit of fudging.

 

[DaveinOlyWA]

generally, the faster the charge, the lower the efficiency. on my Zenn i have no real way of nailing down my efficiency, but a thumbnail estimates show about 75% in winter, something around the mid 80's in summer and my car is in an unheated garage. but i do charge at work out in the elements.

problem is, its a pretty wild estimate coupled with the fact that i only track incoming charge while at home (i am afraid someone will swipe my Kill a watt. plus the charging stations i use are covered and the kill a watt essentially does not fit well)

now i have to say that the system i am using is probably one of the worst. my charger heats up to near the threshold of pain for some i am guessing. its so bad that while home, i pop the hood to let warm air escape. i doubt the Nissan charger will be as bad.

plus, the Nissan charger is going to be charging on a completely different parameter than mine. mine simply charges as if i had a single 72 volt battery. i am guessing the Nissan charger will not which will reduce losses from heat. so i expect Nissan to be in the upper 80's to low 90's

 

[wsbca]

I started out thinking, naively, that charging would be fairly efficient - that is to say that an AC KwH from my solar system (or the grid) would mostly make it into the car - I'm not sure what mostly realistically is, sounds like people are guessing around 90%. The lower "mostly" is, the more I probably undersized my solar system. I should have known better since when researching our solar system I was well aware of the inefficiencies on the path between the collectors and the inverter output. If charging only operates at 75%, I'm going to be pretty bummed. But that's water under the bridge at this point.

What I'm wondering about now (probably a dumb question) is what the reality of battery deterioration over time means for overall efficiency. Is it more like the battery will end up only holding X% of 24KwH, but that lower amount of energy can be stuffed into the car at the same nominal efficiency (keeping the cost per mile consistent, and just diminishing the range), or will it be that you still have to push a "full tank" worth of KwH at the car to get it to think it's 'full', plus you won't go as far? That is to say, will the deteriorated battery still suck up 24KwH plus the baseline charging inefficiency from the wall, or will it effectively become a smaller battery, and take less to charge?

 

[DarkStar]

What I'm wondering about now (probably a dumb question) is what the reality of battery deterioration over time means for overall efficiency. Is it more like the battery will end up only holding X% of 24KwH, but that lower amount of energy can be stuffed into the car at the same nominal efficiency (keeping the cost per mile consistent, and just diminishing the range), or will it be that you still have to push a "full tank" worth of KwH at the car to get it to think it's 'full', plus you won't go as far? That is to say, will the deteriorated battery still suck up 24KwH plus the baseline charging inefficiency from the wall, or will it effectively become a smaller battery, and take less to charge?

If the capacity of the cell is reduced, it will take less energy to recharge the cell.

For example, I estimate that for the 24 KWh battery, it will take about 27 KWh of energy to take it from 0% to 100%. If the capacity eventually is reduced to a total of 12 KWh, it should take about 13.5 KWh (from 0% to 100%) before indicating a complete charge, not 27 KWh.

 

[DaveEV]

I would expect the 120V 1.4kW "trickle" charge and the 240V 3.3kW "regular" charge to have similar overall efficiencies.

The higher voltage charge will typically be a percent or two more efficient thanks to reduced conversion losses, but the battery will probably absorb the range slightly less efficiently. I don't expect the difference in either to be more than a percent or two different.

Note that as evnow earlier noted, the 3.3 kW charge is really just barely above the rate you'd consider a trickle charge which is typically a C/10 rate. You don't normally see big differences in battery charging efficiency until you start looking at charging rates over C/2 with the high power batteries used in EVs. There is typically no need to reduce the charge rate further than C/10 at the end of a charge. All these rates will be slightly different depending on exact battery chemistry.

Just keep in mind that Nissan is limiting QC charge rates to about 1.5C (when the pack 80% or less full) and limiting regen to about 1C (also very likely to be limited at higher charge states as well - expect to see very little regen capability above 95% charge). That should give you an idea at which point charging faster results in significantly reduced efficiency.

I fully expect the Argonne/DOE lbs or some other enterprising individual to disassemble the Leaf and perform full tests on individual components. For example, see the Argonne/DOE reports on each generation of the Prius operation and efficiency so none of this will remain a secret for too much longer.

 

[TomT]

One thing to keep in mind: The L1 and L2 power docks are not chargers. The charger is built in to the car. The power dock simply provides AC power to the vehicle under control of the vehicle charger built in to the car.

L3 DC charging is a completely different story and that unit is in fact the charger itself, remotely controlled by the vehicle.

Tom

 

[EVDRIVER]

One thing to keep in mind: The L1 and L2 power docks are not chargers. The charger is built in to the car. The power dock simply provides AC power to the vehicle under control of the vehicle charger built in to the car.

L3 DC charging is a completely different story and that unit is in fact the charger itself, remotely controlled by the vehicle.

Tom

Some people get this, others refuse to accept this and insist on calling an EVSE a charger calling it "semantics", etc.

 

[sparky]

Slightly off topic but I just learned from the Bl!nk EVSE folks that the residential unit I'll be getting uses 30 W on standby.
I had a feeling this unit was gonna be an energy pig.
That's what happens with all that fancy display, WiFi stuff.
Seems like nothing, but after I installed my PV I went through my house and got rid of all the phantom loads or put them on timers... equivalent to a couple of solar panels in savings.

30W "standby" is about one full LEAF charge per month. Can't put the Bl!nk on a timer though.

 

[Coffee_Slurry]

You could always trip the breaker when you're not using it.

30W sounds high. When it's not charging, there's just the WiFi, backlit touchscreen, Cellular modem, Zigbee, and.. hmm.. 30W you say.

 

[mitch672]

30 watts / month is 21,600 watts total/month (24 hours/day * 30 days/month), of course for some # of those hours, the blink will be in use (6-8 hours/day?), so you can't really count those hours. It sounds more like 2/3's of the time it's not in use, so say 14,000 watts is wasted, or 14KW / month, so yeah, it's gonna cost you a couple bucks month..

259,200 watts per year total. or 259KW/year, I would discount that by 1/3 to 1/4 as it will be in use for 6-8 hours day.

at my rate of .11/Kwh, that comes out to $28.49/year, for the full 259KW... more like 168KW should be counted as waste.

Is this really a big deal?

 

[palmermd]

the blink will be in use (6-8 hours/day?), so you can't really count those hours....
at my rate of .11/Kwh, that comes out to $28.49/year, for the full 259KW... more like 168KW should be counted as waste.

30 watts overhead cannot be ignored when charging the car. Overhead power consumption exists 24hr/day, it does not go away when the EVSE is passing current.

 

[mitch672]

the blink will be in use (6-8 hours/day?), so you can't really count those hours....
at my rate of .11/Kwh, that comes out to $28.49/year, for the full 259KW... more like 168KW should be counted as waste.

30 watts overhead cannot be ignored when charging the car. Overhead power consumption exists 24hr/day, it does not go away when the EVSE is passing current.

you can ignore it, when its in use, as its required for it to function.

If you don't like it, buy another EVSE, but my guess is, they are all going to have some standby current.

 

[TomT]

Since the EV Project is giving me a free charger, I won't begrudge them their 30 watts. Frankly, I wouldn't worry about it much anyway... Regardless, I suspect that the actual standby power consumed will be less than that...

the blink will be in use (6-8 hours/day?), so you can't really count those hours....
at my rate of .11/Kwh, that comes out to $28.49/year, for the full 259KW... more like 168KW should be counted as waste.

30 watts overhead cannot be ignored when charging the car. Overhead power consumption exists 24hr/day, it does not go away when the EVSE is passing current.

you can ignore it, when its in use, as its required for it to function.

If you don't like it, buy another EVSE, but my guess is, they are all going to have some standby current.

 

[sparky]

You could always trip the breaker when you're not using it.

30W sounds high. When it's not charging, there's just the WiFi, backlit touchscreen, Cellular modem, Zigbee, and.. hmm.. 30W you say.

True, although I don't think the EVP folks are cool with that, since they want to retrieve info often. 30W is what "they" say. I emailed Bl!nk and asked for the standby power when it's not charging.

30 watts / month is ....259,200 watts per year total. or 259KW/year,....
Is this really a big deal?

Yeah, I'm not fretting; just disappointed that a device predicated on efficiency is itself inefficient. To unwind my meter of 300kWh/year is a 200W solar panel on my roof. I go through this calc often as I try to trade off replacing incandescents with LEDs. So far it's about a wash between paying for photons->electrons or electrons->photons.

 

[Coffee_Slurry]

30 watts / month is 21,600 watts total/month

...

Your units are all messed up.
I feel like I'm becoming the "kW != kWh" grammar nazi here, but come on.. we're supposed to be the EV cognoscenti, right?

kW is instantaneous power. If the Blnk EVSE mooches 30W continuously, it adds about 21 kWh a month to your electric bill.

When your whole Baseline is 300 kWh for the month, that's not minor.

 

[palmermd]

you can ignore it, when its in use, as its required for it to function.

If you don't like it, buy another EVSE, but my guess is, they are all going to have some standby current.

Yes, 30 watts overhead is required for this unit to function. but it is a larger overhead consumption than is necessary for a relay.

My point is 30 watt consumption is 24 hr/day. 30 watts is high. I suspect most will only draw 5 watt overhead, so this unit seems to have a large overhead to run the added communications functions.

But you are correct. Even these huge 600% increases in the overhead do not cost so much that it is critical to most people in the purchase decision.

 

[mitch672]

30 watts / month is 21,600 watts total/month

...

Your units are all messed up.
I feel like I'm becoming the "kW != kWh" grammar nazi here, but come on.. we're supposed to be the EV cognoscenti, right?

kW is instantaneous power. If the Blnk EVSE mooches 30W continuously, it adds about 21 kWh a month to your electric bill.

When your whole Baseline is 300 kWh for the month, that's not minor.

21,600 watts is 21.6Kw/month, I see no problem here. and to the EV Project folks, if you are complaining about $25/year for 3 years to run the "free" EVSE provided to you, feel free to send it to one of the more appreciative folks who has to shell out a minimum of $800-$2000 for an EVSE they have to buy. In other words, don't look a gifthorse (government) in the mouth

http://wiki.answers.com/Q/Where_does_the_expression_Don't_look_the_gift_horse_in_the_mouth_come_from