Complicated 120V charging and usable driving range question

[leaftryer]

If I started off Monday morning with a 100% charge in a 2012 Leaf and can reliably charge with 120V for 10 hours per night Monday -Thursday night, how many miles should I be able to comfortably drive at 60 mph Monday to Friday during the day and still have at least 10 miles reserve range remaining before charging Friday night?
If I were to then charge 14 hours Friday, Saturday and Sunday nights, how many miles at that same speed could I drive on the weekend and still be guaranteed to be back to 100% charge on Monday morning?

I know I won't be driving constantly 60 mph, but I want enough leeway to compensate for constant air conditioning or heat use even if I am mostly driving slower than that around town.

 

[ElectricVehicle]

If I started off Monday morning with a 100% charge in a 2012 Leaf and can reliably charge with 120V for 10 hours per night Monday -Thursday night, how many miles should I be able to comfortably drive at 60 mph Monday to Friday during the day and still have at least 10 miles reserve range remaining before charging Friday night?
If I were to then charge 14 hours Friday, Saturday and Sunday nights, how many miles at that same speed could I drive on the weekend and still be guaranteed to be back to 100% charge on Monday morning?

I know I won't be driving constantly 60 mph, but I want enough leeway to compensate for constant air conditioning or heat use even if I am mostly driving slower than that around town.

Hey! Who got the word problem from the math book and psted it here on the forums?!? :lol:

10 hours of charging/night at 4.5 LEAF miles of range per hour of 120V charging = 45 LEAF miles of range charged each night.

Monday - Thursday night = 4 nights * 45 LEAF miles of range charged each night = 180 LEAF miles of range charged week nights (Mo - Th)

Starting with full charge = 100 LEAF miles of range.

Total Monday full charge + Mo - Th night charging = 100 + 180 = 280 LEAF miles

At 60 mph 82 miles = 100 LEAF miles. (or 1 LEAF mile = 0.82 60 mph miles)

Total charging = 0.82 60mph miles/LEAF mile * 280 LEAF miles = 230 60mph miles

230 60mph miles - 10 reserve miles = 220 60mph miles/week

220 60mph miles/week / 5 days/week = 44 60mph miles/day (Mo - Fr)

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295" onclick="window.open(this.href);return false;

 

[ElectricVehicle]

Are you limited to 120V charging?

http://evseupgrade.com/" onclick="window.open(this.href);return false;

http://www.quick220.com/" onclick="window.open(this.href);return false;

When we know more about your situation, we may be able to identify some more or faster charging opportunities, at home, at work or some place you frequent for shopping or lunch. What area of what city are you located in - home and work?

 

[leaftryer]

Are you limited to 120V charging?

http://evseupgrade.com/" onclick="window.open(this.href);return false;

http://www.quick220.com/" onclick="window.open(this.href);return false;


When we know more about your situation, we may be able to identify some more or faster charging opportunities, at home, at work or some place you frequent for shopping or lunch. What area of what city are you located in - home and work?

Yes, I am limited by the cost of rewiring to a detached garage. I am looking at a lot of money in wiring costs. There is only 1 circuit existing in the garage so quick220 is not an option. The cost of a 240V EVSE would be in addition to wiring costs. I don't want to invest that much money when I may move in a year or 2 and I may only lease the car for 3 years. I would go back to a non EV if the loss of tax credits make 2015 EV lease pricing even more expensive than leasing a Leaf is today. Wouldn't it be over $500 after tax per month to lease a 2012 SL in California for 36K miles without out the cap reduction?
The Nissan Leaf leasing site doesn't let you change the defaults they plugged in for term and cap reduction, so I can only guess cost.

 

[TonyWilliams]

If I started off Monday morning with a 100% charge in a 2012 Leaf and can reliably charge with 120V for 10 hours per night Monday -Thursday night, how many miles should I be able to comfortably drive at 60 mph Monday to Friday during the day and still have at least 10 miles reserve range remaining before charging Friday night?
If I were to then charge 14 hours Friday, Saturday and Sunday nights, how many miles at that same speed could I drive on the weekend and still be guaranteed to be back to 100% charge on Monday morning?

I know I won't be driving constantly 60 mph, but I want enough leeway to compensate for constant air conditioning or heat use even if I am mostly driving slower than that around town.

At 60mph, you start out Monday morning with a range of 82 miles (21 kWh usable battery capacity * 3.9 miles per kWh at 60 mph = 82 miles), so Monday you can drive 72 miles with a 10 mile reserve on level, not hot or cold roads.

All charges start at 12:01am:

Sunday: 70 miles (or 65 miles, see note), to arrive at 100% in 14 hours tomorrow.

Monday: 14 hour charge * 5 miles per hour charged at 120 volts = 70 miles, which means on the previous Sunday, you could have driven 70 miles to arrive at 100% today.

(note: charging from 80% to 100% is generally significantly slower at 240 or 480 volts, but I don't know about 120 volts). You might consider driving 65 miles on Sunday, or charging an additional hour today.

Tuesday, Wed, Thur:

10 hour charge * 5 miles per hour charged at 120 volts = 50 miles at 60mph
-or-
10 hours * 1.3kWh = 13 kWh * 3.9 miles per kWh = 50 miles

10 miles reserve remains from Monday

Saturday:

14 hour charge * 5 miles per hour charged at 120 volts = 70 miles

10 miles reserve remains

Sunday:

14 hour charge * 5 miles per hour charged at 120 volts = 70 miles (or maybe 65 miles to reach 100% Monday)

10 miles reserve remains


Sunday - 70 miles (or 65 miles)
Monday - 72 miles
Tuesday - 50 miles
Wednesday- 50 miles
Thursday - 50 miles
Friday - 50 miles
Saturday - 70 miles

 

[leaftryer]

If I started off Monday morning with a 100% charge in a 2012 Leaf and can reliably charge with 120V for 10 hours per night Monday -Thursday night, how many miles should I be able to comfortably drive at 60 mph Monday to Friday during the day and still have at least 10 miles reserve range remaining before charging Friday night?
If I were to then charge 14 hours Friday, Saturday and Sunday nights, how many miles at that same speed could I drive on the weekend and still be guaranteed to be back to 100% charge on Monday morning?

I know I won't be driving constantly 60 mph, but I want enough leeway to compensate for constant air conditioning or heat use even if I am mostly driving slower than that around town.

Hey! Who got the word problem from the math book and psted it here on the forums?!? :lol:

10 hours of charging/night at 4.5 LEAF miles of range per hour of 120V charging = 45 LEAF miles of range charged each night.

Monday - Thursday night = 4 nights * 45 LEAF miles of range charged each night = 180 LEAF miles of range charged week nights (Mo - Th)

Starting with full charge = 100 LEAF miles of range.

Total Monday full charge + Mo - Th night charging = 100 + 180 = 280 LEAF miles

At 60 mph 82 miles = 100 LEAF miles. (or 1 LEAF mile = 0.82 60 mph miles)

Total charging = 0.82 60mph miles/LEAF mile * 280 LEAF miles = 230 60mph miles

230 60mph miles - 10 reserve miles = 220 60mph miles/week

220 60mph miles/week / 5 days/week = 44 60mph miles/day (Mo - Fr)

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295" onclick="window.open(this.href);return false;

OK, so it looks like it would handle my current weekday commute with just that overnight charging on 120V.
The only issue would be using more miles on the weekend and still having enough time to get it back to 100% charge by Monday morning.
I read somewhere that charging over 80% is an issue and is not recommended, but if I don't start out with 100% charge on Monday, that will cut my usable range for the week a lot at a 120V charging rate.

 

[ElectricVehicle]

Yes, I am limited by the cost of rewiring to a detached garage. I am looking at a lot of money in wiring costs. There is only 1 circuit existing in the garage so quick220 is not an option. The cost of a 240V EVSE would be in addition to wiring costs. I don't want to invest that much money when I may move in a year or 2 and I may only lease the car for 3 years. I would go back to a non EV if the loss of tax credits make 2015 EV lease pricing even more expensive than leasing a Leaf is today. Wouldn't it be over $500 after tax per month to lease a 2012 SL in California for 36K miles without out the cap reduction?
The Nissan Leaf leasing site doesn't let you change the defaults they plugged in for term and cap reduction, so I can only guess cost.[/quote]
EVSE Upgrade is $239.

How many wires in that circuit to the garage 3? perchance 4? Change the existing wiring to a 240V circuit? If there are just a few light 120V loads, put a 240 to 120 step down transformer in the garage for those loads and hacve 240V for the car?

Not trying to tell you what to do or anything, just anytime I see an outlet I think about the possibilities of EV charging!

One fellow near me works at the water district and plugs in at 120V at work. I can't recall if his one way commute is 40 or 60 miles, but the 8 hours of 120 at work means no worries whatever he needs to do. (Well, except for driving from N. CA to Mexico in a single day for example..)

If you care to share, what are your daily driving needs?

 

[TonyWilliams]

I read somewhere that charging over 80% is an issue and is not recommended, but if I don't start out with 100% charge on Monday, that will cut my usable range for the week a lot at a 120V charging rate.

If you leased the car, you don't care.

If you bought, honestly, I don't think it'll be an issue.

 

[ElectricVehicle]

OK, so it looks like it would handle my current weekday commute with just that overnight charging on 120V.
The only issue would be using more miles on the weekend and still having enough time to get it back to 100% charge by Monday morning.
I read somewhere that charging over 80% is an issue and is not recommended, but if I don't start out with 100% charge on Monday, that will cut my usable range for the week a lot at a 120V charging rate.

If you only do the 3 year lease, the 100% charging shouldn't be noticeable during the lease period. Charging to 80% is still more range than you would get from each night's charging, so if you're using that mush daily, you'll only hit 100% on Sunday night. The rest of the nights would be progressively lower. As you get used t the LEAF, you can decide when you need 80% or 100%. Even if you do 100% charging everyday - I think that translates to something like a 10% additional capacity loss over 8 years , or say 100,000 miles compared to 80% charging. Where'd I get those numbers - well I made them up based on vague recollections, but even so, 80% charging is better but 100% is ok with slighlty faster degradation. We also don't know long term what it will be real world since none of us have had our LEAFs for over a year yet!

 

[leaftryer]

Not likely that the existing outlet can be changed. There is an outlet in the ceiling used for the garage door opener and another outlet on the wall and they are very likely sharing a single circuit. That would block changing the outlet even if the outlet had the necessary extra wiring.
If it could be changed to 240, that would mean nothing else could be used in the garage like a fan, portable light, vacuum or power tools even when the car was't charging.

 

[smkettner]

$50 gets you a 1500w 240 -> 120v step down transformer to run the opener and various accessories.
Or you could get complex with a 240v charger to maintain a couple batteries and an inverter to run the 120v stuff.

Ideally you would have conduit where you could pull one more #12 wire or #14 wire to have a 240/120 circuit.

 

[leaftryer]

$50 gets you a 1500w 240 -> 120v step down transformer to run the opener and various accessories.
Or you could get complex with a 240v charger to maintain a couple batteries and an inverter to run the 120v stuff.

Ideally you would have conduit where you could pull one more #12 wire or #14 wire to have a 240/120 circuit.

I can get another electrician to look at it and get another quote and see if he has lower cost ideas to get the job done. It is a labor intensive and expensive job to run the wires from where the circuit breakers are on the main house to the detached garage safely and not as an eyesore with conduit running along the outside of the house. I don't want to look at exposed conduit outside and it would be a HOA violation and a resale issue even if I didn't care how it looked.

On the other hand, if 120V can do the job well enough, I could just use the standard charger that comes with the car for 3 years.
If my commute were to get longer (job change etc.) then I would have to get 240V with an EV because there would not be enough hours after work to handle recharging for a 60 mile round trip commute.

 

[ElectricVehicle]

Not likely that the existing outlet can be changed. There is an outlet in the ceiling used for the garage door opener and another outlet on the wall and they are very likely sharing a single circuit. That would block changing the outlet even if the outlet had the necessary extra wiring.
If it could be changed to 240, that would mean nothing else could be used in the garage like a fan, portable light, vacuum or power tools even when the car was't charging.

Yup, that's the way it is sometimes... Things to work as more people get EVs - how do people in high rise apartments charge EVs or EV rental cars... Quick Chargers can help, but they have their own set of cost and siting challenges. That does make this an exciting time to have an EV though, because we're part of working through all these issues - where evs work - where they don't, etc..

Keeo us posted on your EV journey...

 

[fooljoe]

Not likely that the existing outlet can be changed. There is an outlet in the ceiling used for the garage door opener and another outlet on the wall and they are very likely sharing a single circuit. That would block changing the outlet even if the outlet had the necessary extra wiring.
If it could be changed to 240, that would mean nothing else could be used in the garage like a fan, portable light, vacuum or power tools even when the car was't charging.

That's why he mentioned a step down transformer for the 120V loads. Anyway people, there's already an extensive thread over here where leaftryer has explained his situation and received all kinds of helpful advice on ways to get L2 charging. leaftryer, I notice your profile indicates a delivery date of 8/27/11, but according to that other thread you're still on the fence about whether a Leaf would work for you. Might want to fix that.

 

[leaftryer]

Not likely that the existing outlet can be changed. There is an outlet in the ceiling used for the garage door opener and another outlet on the wall and they are very likely sharing a single circuit. That would block changing the outlet even if the outlet had the necessary extra wiring.
If it could be changed to 240, that would mean nothing else could be used in the garage like a fan, portable light, vacuum or power tools even when the car was't charging.

That's why he mentioned a step down transformer for the 120V loads. Anyway people, there's already an extensive thread over here where leaftryer has explained his situation and received all kinds of helpful advice on ways to get L2 charging. leaftryer, I notice your profile indicates a delivery date of 8/27/11, but according to that other thread you're still on the fence about whether a Leaf would work for you. Might want to fix that.

I don't know why there is a delivery date listed. That must just be the date I opened the forum account.
240v just may not work at a cost that makes sense in my situation, so i want to see is 120V could be adequate.

 

[fooljoe]

Ideally you would have conduit where you could pull one more #12 wire or #14 wire to have a 240/120 circuit.

Apologies in advance to all who would cry foul at the suggestion, but in a pinch couldn't he possibly use the existing ground wire as a neutral for the 120V loads? Assuming of course that the ground wire is a #12 insulated wire and not just bare copper. Certainly it's not recommended, but then again this is basically what my old 3-wire dryer circuit does, with a shared neutral/ground wire for a 240/120 circuit.

I do like the suggestion of a step-down transformer - hadn't thought of that one.

 

[fooljoe]

I don't know why there is a delivery date listed. That must just be the date I opened the forum account.
240v just may not work at a cost that makes sense in my situation, so i want to see is 120V could be adequate.

Looks like the delivery date is gone now - perhaps just a glitch in the matrix. Personally, I wouldn't want to rely on just 120v, but that's just me. I know smkettner has been using L1 only for some time, so you might want to read through some of his posts or PM him for the real world perspective on how that works, instead of just relying on math problems. Anyway, I hope by now you can see that despite the apparent difficulties of your situation, if you're willing to be flexible and get your hands dirty 240v charging can still be had for cheap. Take the plunge, get a Leaf, try it out on L1 for a while, and if it's not working out get the EVSE upgraded and switch that garage circuit to 240v, or run an above ground extension cord for charging, or trench it yourself, or whatever. You'll make it work without blowing your budget one way or another.

 

[planet4ever]

OK, here is yet another way to solve the math problem:

From Tony's chart, which ElectricVehicle already imbedded here, you should be able to get 3.9 m/kWh at 60 mph. We don't really have a very good handle yet on charging efficiency at 120v, but I'll be conservative and use the lowest value I've seen calculated, 68%. My other assumption will be that available capacity is 21 kWh.

Unlike Electric Vehicle and TonyWilliams I'm going to start from the assumption that there is no taper at the end of the weekday charges, since you will not be charging beyond 80%. I will also point out that with your setup there might be some voltage sag, but to some people's consternation we have learned that the charger in the car will pull more than the rated amps when the voltage is low.

Monday through Friday:

10 hrs * 12 amps * 120 volts = 14.4 kWh at the wall
14.4 kWh * 68% efficiency = 9.8 kWh to the battery
21 kWh initial + (4 * 9.8 kWh) = 60.2 kWh available

You want to reserve 10 miles, which at 3.9 m/kWh = 2.6 kWh. That leaves 57.6 kWh, which at 3.9 m/kWh = 225 miles.
So you should be able to drive 45 miles/day Mon-Fri.

This is in line with the 46 that ElectricVehicle came up with, but considerably lower than the 54 Tony claimed. One big difference is that Tony was in effect assuming a much higher charging efficiency. He quoted 5 miles range per hour of charging, where ElectricVehicle assumed only 3.7! (4.5 * .82)

Friday night through Sunday night:

The manual says you can carge from Low Battery warning to 100% in 21 hours at 120v. Tony says LB is at 17.1%, which would be 3.6 kWh. You've allowed only 14 hours, so had to precharge the equivalent of 7 hours above the LB level.

7 hrs * 12 amps * 120 volts * 68% = 6.9 kWh already in the battery, plus the 3.6 kWh below LB, or 10.5 kWh. (That is in addition to whatever you use on Sunday.) I went all around the bush on that one to avoid worrying about charge rate taper as we approach 100%.

Friday and Saturday nights you would have charged:
2 nights * 14 hrs * 12 amps * 120 volts * 68% = 27.4 kWh
27.4 + 3.6 - 10.5 = 20.5 kWh is what you have available for use.
3.9 m/kWh * 20.5 kWh = 80 miles total for Saturday and Sunday.

Again, Tony's estimate (135-140 miles) is much higher.

Ray

Disclaimer: It is midnight, and I haven't checked all my calculations, so if you end up calling a tow truck, don't blame me.

 

[surfingslovak]

It is midnight, and I haven't checked all my calculations, so if you end up calling a tow truck, don't blame me.

Excellent post! Thoroughly enjoyed reading it...

 

[LTLFTcomposite]

Ideally you would have conduit where you could pull one more #12 wire or #14 wire to have a 240/120 circuit.

Apologies in advance to all who would cry foul at the suggestion, but in a pinch couldn't he possibly use the existing ground wire as a neutral for the 120V loads? Assuming of course that the ground wire is a #12 insulated wire and not just bare copper. Certainly it's not recommended, but then again this is basically what my old 3-wire dryer circuit does, with a shared neutral/ground wire for a 240/120 circuit.

I do like the suggestion of a step-down transformer - hadn't thought of that one.

I'm having a hard time picturing how electrical service could run from the house (where we assume the service panel is located) to a detached garage with the wires NOT in conduit. Maybe in a rural setting where you can do whatever you want but this guy is talking about HOAs.

If there's conduit from the service panel to the garage, my suggestion would be to pull a third conductor and add a little subpanel in the garage so you can have a 240 outlet on a 20A double pole breaker and the outlets and lighting on one or more 120V circuits. Probably preferable to pull all new #10 wire so the subpanel can have a 30A feed. Without seeing the situation though it's hard to say if any of this fits the situation.