is it safe to assume?

[SKY888]

Hello,

for the past month since I had my 2012 Nissan SL, the dash gauge tells me that I average 3.6 miles per kwh in the cold month of Jan-Feb 2013 here in Rhode Island


is it safe to assume that:

1.) the miles per kwh will increase once the cold weather disappears, with the same driving style?

2.) with 3.6 miles/kwh, if I drive 15,000 miles for the whole year and with $0.15 kwh in Rhode Island.
my calculation will be 15,000/3.6 = 4167 kwh

4167 kwh x .15 = $625


basically, I will be paying $625 or less for my 15,000 mile commute for the whole year?



thanks!

 

[DesertDenizen]

I average 5.7 m/kwh in the summer, and it is 5.1 in the winter, so yes, you can anticipate an increase when the seasons change.

 

[ksnogas2112]

Sky,
1. yes. I was getting ~3.6 during the coldest parts of winter but i'm getting 4.5 for February since i'm not using the heat so much.
2. not quite, there's a vampire factor in charging that causes you to loose a little on the charge so you cost would be a little more than $625 but probably not more than $75 for the year but there are guys with better math skills than mine that can settle it for sure. But that's a nice s.w.a.g.

 

[SKY888]

thanks for the reply guys!

it made me more happy with the Leaf!

 

[SKY888]

Sky,
2. not quite, there's a vampire factor in charging that causes you to loose a little on the charge so you cost would be a little more than $625 but probably not more than $75 for the year but there are guys with better math skills than mine that can settle it for sure. But that's a nice s.w.a.g.

I was assuming $625 or less because, like what you guys mentioned the miles/kwh will increase. The $625 I listed was using ONLY 3.6 miles/kwh which is probably the lowest I'll get (during winter). But the rest of the seasons, I will get more miles/kwh (probaby around 4 miles/kwh for)

So even with the vampire factor, should I still be expecting $625 or less?

 

[occ]

Sky,
2. not quite, there's a vampire factor in charging that causes you to loose a little on the charge so you cost would be a little more than $625 but probably not more than $75 for the year but there are guys with better math skills than mine that can settle it for sure. But that's a nice s.w.a.g.

I was assuming $625 or less because, like what you guys mentioned the miles/kwh will increase. The $625 I listed was using ONLY 3.6 miles/kwh which is probably the lowest I'll get (during winter). But the rest of the seasons, I will get more miles/kwh (probaby around 4 miles/kwh for)

So even with the vampire factor, should I still be expecting $625 or less?

That's a good estimate to get the high end of your usage.

If you have a 240v EVSE then the charging is about 90% efficient, and if you use the 120v that came with the LEAF then it is around 85%.

So for your usage 4167kwh/0.9 = 4630kwh out of the wall. That's 463khw more or ~$69. Good guess ksnoga.

 

[SKY888]

I do have a 240 Aerovironment EVSE

thanks for the help guys!

 

[ERG4ALL]

Are you on time-of-use billing with your electric utility? That $0.15 figure is right between what we pay for off peak and on peak. But to answer your question, we've had our 2011 for almost two years. One winter it was up in the mountains, and I noticed significant less mileage in the winter even without using the heater. You're probably aware that Nissan uses a passive battery management system. Thus, the battery is 6" off the road surface and will get cool. Other brands like the Ford, Coda and Tesla have active BMS's but I haven't heard from anyone how much that alleviates the phenomenon.

 

[planet4ever]

If you have a 240v EVSE then the charging is about 90% efficient, and if you use the 120v that came with the LEAF then it is around 85%.

It's actually closer to 85% at 240v and 75% at 120v. So based on SKY888's original numbers, and using the AeroVironment EVSE, it would be $625/.85 = $735. However, as others have said, he will get much better mileage in the summer.

ksnogas2112 referred to a vampire factor. That term is normally used to refer not to the loss while charging but to energy lost all the time an electrical appliance is plugged in, whether it is being used or not. The AeroVironment EVSE does draw a little current all the time. I don't know the number, but I would be surprised if it amounted to more than a dollar or two per month at a $0.15/kWh rate.

Ray

 

[DaveinOlyWA]

Hello,

for the past month since I had my 2012 Nissan SL, the dash gauge tells me that I average 3.6 miles per kwh in the cold month of Jan-Feb 2013 here in Rhode Island


is it safe to assume that:

1.) the miles per kwh will increase once the cold weather disappears, with the same driving style?

yes because

**cold air is denser. in Summer your car simply does not have to work as hard to maintain speed

** AC is MUCH more efficient than heat. the freezing you might do in Winter is not an issue in Summer. A/C uses about a third as much power

2.) with 3.6 miles/kwh, if I drive 15,000 miles for the whole year and with $0.15 kwh in Rhode Island.
my calculation will be 15,000/3.6 = 4167 kwh

4167 kwh x .15 = $625

no. your 3.6 from the dash is your efficiency out of the battery. what you did not calculate is the heat loss and BMS overhead when the power is going INTO the battery which is about 13-15% if using 240 VAC at 16 amps.

 

[SKY888]

Are you on time-of-use billing with your electric utility? That $0.15 figure is right between what we pay for off peak and on peak. But to answer your question, we've had our 2011 for almost two years. One winter it was up in the mountains, and I noticed significant less mileage in the winter even without using the heater. You're probably aware that Nissan uses a passive battery management system. Thus, the battery is 6" off the road surface and will get cool. Other brands like the Ford, Coda and Tesla have active BMS's but I haven't heard from anyone how much that alleviates the phenomenon.

unfortunately, we only have one flat rate

 

[SKY888]

If you have a 240v EVSE then the charging is about 90% efficient, and if you use the 120v that came with the LEAF then it is around 85%.

It's actually closer to 85% at 240v and 75% at 120v. So based on SKY888's original numbers, and using the AeroVironment EVSE, it would be $625/.85 = $735. However, as others have said, he will get much better mileage in the summer.

ksnogas2112 referred to a vampire factor. That term is normally used to refer not to the loss while charging but to energy lost all the time an electrical appliance is plugged in, whether it is being used or not. The AeroVironment EVSE does draw a little current all the time. I don't know the number, but I would be surprised if it amounted to more than a dollar or two per month at a $0.15/kWh rate.

Ray

thank you for your input.

so only 85% huh?


by the way, if I leave my EVSE attached to my car the whole night, even if the car is already fully charged while I'm charging..................will I be wasting any electricity? or something?

 

[DesertDenizen]

unfortunately, we only have one flat rate


I guess I am fortunate. I am on solar metering and the flat rate is .08. But it is moot as most months I net out at near zero electricity so there is no over/under.

 

[dgpcolorado]

...so only 85% huh?

by the way, if I leave my EVSE attached to my car the whole night, even if the car is already fully charged while I'm charging..................will I be wasting any electricity? or something?

The power use by an EVSE that isn't charging is just a few watts. It won't be significant compared to the power used to charge the car. The reason charging has efficiency losses is that some is lost to heat and the charger and inverter cooling system uses power to circulate coolant (the pumps you hear when charging). This overhead is fairly constant. NREL calculated LEAF charging at 86% efficient at 240 Volts, 16Amps; this agrees pretty well with my numbers and those of others here. 120 Volt, 12 Amp charging is about 75% efficient since it is a lot slower.

To put the standby EVSE power in perspective, consider that 240 V, 16 A charging draws 3840 Watts. If the EVSE has a standby power draw of 5 watts, it is pretty tiny by comparison. I think my EVSE Upgrade Nissan/Panasonic device is supposed to draw about one to two watts when not charging. It is trivial.

 

[DNAinaGoodWay]

Need to clarify this:

Is voltage 220 or 240? I've seen both.

If 240, and drawing at 16A, so charging at 3.84 kW, why do they say the inboard charger is 3.3 kW?

Is it because voltage is 200 in Japan?


I get 3.7 m/kWh avg so far, all winter conditions, using heat liberally, but not much highway.

When it was 50 deg the other day, I used no heat, the battery was warmer, and on the 10 miles to work it did 5.1 m/kWh on a 40 mph road.

In RI you'll also have denser air just being closer to sea level, here it's about 800 ft.

 

[Boomer23]

If you have a 240v EVSE then the charging is about 90% efficient, and if you use the 120v that came with the LEAF then it is around 85%.

It's actually closer to 85% at 240v and 75% at 120v. So based on SKY888's original numbers, and using the AeroVironment EVSE, it would be $625/.85 = $735. However, as others have said, he will get much better mileage in the summer.

ksnogas2112 referred to a vampire factor. That term is normally used to refer not to the loss while charging but to energy lost all the time an electrical appliance is plugged in, whether it is being used or not. The AeroVironment EVSE does draw a little current all the time. I don't know the number, but I would be surprised if it amounted to more than a dollar or two per month at a $0.15/kWh rate.

Ray

My AV unit draws about 6 Watts.

 

[EatsShootsandLeafs]

No idea how y'all get these miles. I just checked--am in NY state. My fall/2012 mileage (got car at start of sept) averaged to 3.4. For 2013 so far it's 2.9. Looks like I'll probably, including summer, average around 3.3 over a year. Btw I'm regularly driving without any heat at all, even below freezing, just to maintain distance. At $4/gas it's still the equivalent of about 90 mpg or so in a gas-drinking car, so I'm ok with it.

Batteries are less efficient when cold so producing the same energy you'll lose capacity faster.

 

[TonyWilliams]

Need to clarify this:

Is voltage 220 or 240? I've seen both.

In a nutshell:

100/200 - Japan
208/277 - USA commercial
120/240 - USA residential
230 - the rest of the world

If 240, and drawing at 16A, so charging at 3.84 kW, why do they say the inboard charger is 3.3 kW?

Is it because voltage is 200 in Japan?

No, it's because the charger is operating at about 85% efficiency at 16amps. So, the 3.84kW draw from "the wall", 85% of 3.84kW is about 3.3kW.

In RI you'll also have denser air just being closer to sea level, here it's about 800 ft.

And they may have higher temperatures at that lower elevation, hence it is possible that the air density is "thicker" at 800 feet.

I wouldn't waste much time figuring out air density on the east coast of the USA with it's modest elevation changes. Temperature, however, will be an entirely different situation, since it can get quite cool and equally hot. Use about 1% change in range per 1000 feet change in density altitude.

Please check out the Range Chart.

 

[FairwoodRed]

Need to clarify this:

Is voltage 220 or 240? I've seen both.

If 240, and drawing at 16A, so charging at 3.84 kW, why do they say the inboard charger is 3.3 kW?

Is it because voltage is 200 in Japan?

I get 3.7 m/kWh avg so far, all winter conditions, using heat liberally, but not much highway.

When it was 50 deg the other day, I used no heat, the battery was warmer, and on the 10 miles to work it did 5.1 m/kWh on a 40 mph road.

In RI you'll also have denser air just being closer to sea level, here it's about 800 ft.

240 volts. While the input may be up to 3.84kW, the output to the battery is only up to 3.3kW.

No idea how y'all get these miles. I just checked--am in NY state. My fall/2012 mileage (got car at start of sept) averaged to 3.4. For 2013 so far it's 2.9. Looks like I'll probably, including summer, average around 3.3 over a year. Btw I'm regularly driving without any heat at all, even below freezing, just to maintain distance. At $4/gas it's still the equivalent of about 90 mpg or so in a gas-drinking car, so I'm ok with it.

Batteries are less efficient when cold so producing the same energy you'll lose capacity faster.

I average 3.4 in the winter and 4.x in the summer here in the Seattle area. But, when I try, I can hit 4.9 in the winter. Some tips that I use to improve my efficiency are:

Ecomode to moderate heater draw.
Aftermarket seat heaters.
Switch to lower speed surface roads.
Slow down early rather than stop.
Coast rather than regen.
In hilly spots, maintain constant throttle rather than constant speed.
Keep traction power as low as possible and watch it like a hawk.

None of that is very fun, but a nice skill to have for when I need to push the limits of the car.

 

[ERG4ALL]

We get on average about 4.5 to 4.6 m/kWh. As previously stated driving in ECO and anticipating stops to maximize regen and keeping the speed down to 60 - 65 mph and planning your route so that it isn't freeway all the way all help. One other thing I do is to use the cruise control (CC) even on city streets (e.g. 40 - 45 mph) when it isn't bumper to bumper. By anticipating, all I have to do is touch the brake pedal to get off of CC. This is also handy when traveling on city freeways. I usually stay in the right lane at the posted limit of 55 or 65. I have actually passed some other drivers and trucks, however, I don't do like the hell-bent types that are traveling at 80 mph.