Nissan Leaf EV

[veloman]

why can't you charge past 80%? That seems like a huge drawback on a car that already has its biggest issue of range.

You can. 80% maximizes longevity of the battery, though.

Well it makes sense to only charge to 80% if you KNOW you won't need the full range. I'll probably be doing that with my new ebike battery since it will have 17-20 mile range and I usually only use 6-10 miles at a time. I already keep it in the 50-70% range overnight whenever possible.

 

[Toshi]

2013 changes: http://www.thetruthaboutcars.com/2012/11/new-nissan-leaf-promises-you-more-or-less/

Time will tell whether these JDM changes make it in full to the (Smryna built?) USDM model.

Key changes include: 

- 10% more range, possibly by virtue of strengthened regenerative braking
- optional leather upholstery and a Bose stereo
- possibly most significantly, the substitution of a heat pump in place of a pure resistive heating element.

This last is important because the >1 coefficient of performance of a heat pump will halve or perhaps cut by two thirds heating loads and the resultant range loss. 

In any case, the outside appearance isn't changed. Here's the outside, in case you've been living under a rock, as well as the new interior leather:

Other notable vehicles in terms of HVAC: The PHEV Prius prototypes (but not the production model) also employed a heat pump, and the Volvo C30 EV prototypes employ a small biodiesel burner for auxiliary heat, of all things. Finally, the series 200 Land Cruiser and its Lexus cousin boast of the following:

In extreme cold situations, the Land Cruiser’s auxiliary Positive Temperature Coefficient (PTC) heater warms air instantly by passing it over an electrically heated ceramic element.

 

[ls7corvete]

All sounds like good news, Some summary (off the top of my head):
15% more range
10% lighter
Couple more cubic feet cargo space
Better HVAC
6,000$ USD cheaper (at least in Japan)

Built in Tennessee now too! Cant wait.

 

[LeftieBiker]

If they have completely replaced the resistive heating with a heat pump, that's going to be a real problem. Heat pumps can't extract usable amounts of heat from the atmosphere below about 45 degrees Fahrenheit. Hopefully they have instead used a heat pump with resistive heating available as needed, just like home heating systems that use heat pumps have. They still need to find a better way to get heat, though. I can think of two ways: capture heat from the braking system, and only use regenerative braking when heat isn't needed, or use a catalytic propane type heater. Since the battery pack overheating issues will limit demand in really hot climates, they need to avoid making the cars uncomfortable in cold climates as well!

BTW, Nissan is now offering leases that consist of $1999 down, $245 a month (all USD) and a 36 month lease length. That's a good deal for someone in a mild climate who doesn't need more than 60 miles or so real world range.

 

[Toshi]

BTW, Nissan is now offering leases that consist of $1999 down, $245 a month (all USD) and a 36 month lease length. That's a good deal for someone in a mild climate who doesn't need more than 60 miles or so real world range.

I've seen SV lease offers for $1,999 down, $199/month x 36 months... Too bad that trim doesn't have a backup camera. (Yes, I saw the thread where an engineer hacked one in. That wouldn't be a good idea on a leased car.)

 

[Jeremy Harris]

If they have completely replaced the resistive heating with a heat pump, that's going to be a real problem. Heat pumps can't extract usable amounts of heat from the atmosphere below about 45 degrees Fahrenheit.

Yes they can, no problem at all. Ask any Canadian or Scandinavian! I've been looking at heat pumps for my new house build, and although I've decided against an air source heat pump (as used in the Leaf) I did check the specs and prices for them. All the units I looked at worked down to -18 deg C or lower (that's around 0 deg F I think). The COP get's down to unity at that point, but pretty much anywhere above that (as long as you can efficiently deice the heat exchanger when its humid) you can get a COP of better than 1. Typically COP for an air source heat pump will be around 2 to 3 in normal use, maybe 4 at its best.

 

[whatever]

they are crazy not using iron phosphates, its a bomb waiting to go off

 

[LeftieBiker]

If they have completely replaced the resistive heating with a heat pump, that's going to be a real problem. Heat pumps can't extract usable amounts of heat from the atmosphere below about 45 degrees Fahrenheit.

Yes they can, no problem at all. Ask any Canadian or Scandinavian! I've been looking at heat pumps for my new house build, and although I've decided against an air source heat pump (as used in the Leaf) I did check the specs and prices for them. All the units I looked at worked down to -18 deg C or lower (that's around 0 deg F I think). The COP get's down to unity at that point, but pretty much anywhere above that (as long as you can efficiently deice the heat exchanger when its humid) you can get a COP of better than 1. Typically COP for an air source heat pump will be around 2 to 3 in normal use, maybe 4 at its best.

Did you read specifically that the heat is coming from the air at those temps? Because home heat pumps do provide heat in that range, but at the colder end it comes from built-in resistive heating elements, not the air. Maybe my knowledge is out of date, but I find it hard to believe that they can scavenge enough heat from the air at those temps...

 

[Toshi]

If they have completely replaced the resistive heating with a heat pump, that's going to be a real problem. Heat pumps can't extract usable amounts of heat from the atmosphere below about 45 degrees Fahrenheit.

Yes they can, no problem at all. Ask any Canadian or Scandinavian! I've been looking at heat pumps for my new house build, and although I've decided against an air source heat pump (as used in the Leaf) I did check the specs and prices for them. All the units I looked at worked down to -18 deg C or lower (that's around 0 deg F I think). The COP get's down to unity at that point, but pretty much anywhere above that (as long as you can efficiently deice the heat exchanger when its humid) you can get a COP of better than 1. Typically COP for an air source heat pump will be around 2 to 3 in normal use, maybe 4 at its best.

Did you read specifically that the heat is coming from the air at those temps? Because home heat pumps do provide heat in that range, but at the colder end it comes from built-in resistive heating elements, not the air. Maybe my knowledge is out of date, but I find it hard to believe that they can scavenge enough heat from the air at those temps...

Page 11 and 14: http://www.nrel.gov/docs/fy11osti/52175.pdf . Still near rated capacity for heating, COP just under 2 at below 0 degrees F.

 

[Jeremy Harris]

Did you read specifically that the heat is coming from the air at those temps? Because home heat pumps do provide heat in that range, but at the colder end it comes from built-in resistive heating elements, not the air. Maybe my knowledge is out of date, but I find it hard to believe that they can scavenge enough heat from the air at those temps...

It's just physics. You can extract heat from air at any temperature right down to absolute zero (-273 deg C, -460 deg F) using a heat pump if you use a suitable heat transfer fluid. The -18 deg C limit for currently available heat pumps (including that in the Leaf) is solely a consequence of using a working fluid that is safe and doesn't damage the atmosphere if it escapes.

Our use of 0 deg C for freezing point, or 32 deg F, is just a consequence of us adopting an couple of oddball heat measurement systems. The point where air has no heat energy at all is 0 deg K, absolute zero. At any temperature above that there is useful heat that can be extracted by cooling the air down further. It makes no difference whether you drop air at 10 deg C to 0 deg C, or drop air at -30 deg C to -40 deg C, you will get the same amount of heat energy out of it.

 

[SamTexas]

Yes. Heat can be extracted from air at any temperature as Jemery said. The question is how efficient? Especially when the de-icing is taken into account. In Houston where humidity is high, it only takes 20 mins for the ice to form.

 

[Jeremy Harris]

Yes. Heat can be extracted from air at any temperature as Jemery said. The question is how efficient? Especially when the de-icing is taken into account. In Houston where humidity is high, it only takes 20 mins for the ice to form.

Yes, icing is a problem, as you either have to reverse the cycle to melt it (which hits efficiency) or use heaters to melt it (which also hit efficiency). Having said that, we have a fair few ASHPs working here now, as domestic home heating systems, and our climate is pretty wet (my weather station is telling me the RH is 97% outside at the moment!). It seems that even with the need to defrost the heat exchanger from time to time you can still get a useful COP, from the stuff I read up when we were looking to fit one. One idea that's been adopted by at least one ASHP manufacturer is to use two parallel heat exchangers with an electronic valve to switch between them. When one ices up it is turned off so that the ice can melt and the other one is used. It adds a bit of weight and size, but the system seems to give a slightly better overall COP in our damp climate than some of the others. Having said that, the mean COP from a report done a couple of years or so ago here ( http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/microgeneration/5045-heat-pump-field-trials.pdf) still gave a result of 1.82, which is a fair bit better than using straight resistive heating.

 

[SamTexas]

One idea that's been adopted by at least one ASHP manufacturer is to use two parallel heat exchangers with an electronic valve to switch between them. When one ices up it is turned off so that the ice can melt and the other one is used.

That method would not work at all, even in Houston where the temperature rarely drops below freezing. On a 5 degree C with 95% RH, my "turned around" window air conditioning unit would ice up within 20mins. Turned it off and it took at least 40 minutes for the ice to completely melt.

 

[Jeremy Harris]

Well, it seemed to work on the demo unit that was being run at a house show I went to last year. Not sure whether they kept the fans running over the heat exchanger that was de-icing or not, my guess is that they probably did in order to speed up the de-ice cycle. The manufacturer was claiming enhanced efficiency over the units that used heaters or reverse cycling to defrost, but TBH, by that point we'd pretty much decided to go for a standing column GSHP, so we weren't really paying too much attention.

 

[liveforphysics]

they are crazy not using iron phosphates, its a bomb waiting to go off

Except we've never seen a leaf burn, and we have seen a dozen or so 4x more expensive iron phosphate battery cars burn.

Remember, after $50million in GM's battery lab test program, an Iron phosphate cell by A123 was rejected over poor safety vs the NMC cells from LG.

One idea that's been adopted by at least one ASHP manufacturer is to use two parallel heat exchangers with an electronic valve to switch between them. When one ices up it is turned off so that the ice can melt and the other one is used.

That method would not work at all, even in Houston where the temperature rarely drops below freezing. On a 5 degree C with 95% RH, my "turned around" window air conditioning unit would ice up within 20mins. Turned it off and it took at least 40 minutes for the ice to completely melt.

You design your heatsink for the environment. If you're making an AC unit heatsink, icing isn't a design criteria, because it's always getting warmed. When you're designing something with the intent of being a heat pump heat sink for all humidity climates, you design it with avoiding icing as a key criteria, and you can achieve that need at the expense of additional heat sink size, wider thicker fin spacing, and a few other tricks.

The best part of putting the heat pump in the leaf, is the electrical components for it will all be in the cabin space as well, so even in some situation where it was so cold you couldn't overcome that outside delta-T to extract heat from the outside air, you still get every watt of power dumped into the pump system as heat for the cabin, so in your worst case scenario you still function as well as a small resistive heater.

Also, I would like to add that OEM's generally test the snot out of these systems before they put them in a car. It's not like they just add a heat pump and don't try it out before it goes into production. They test these systems in the coldest climate test facilities and hottest climate test facilities they can find for months of the most extreme use, continous freezing water spray in -30degC climate chambers until the cars suspension is sagging from all the ice accumulation, or test chambers with asphault heated to 70degC (160F) and radiators/heat exchangers all packed with dust in stagnant air running the AC continuously for weeks at a time. It's not like they just say, hey! Heat pump! And convert all the cars before trying it out in the worst possible conditions.

 

[SamTexas]

You design your heatsink for the environment. If you're making an AC unit heatsink, icing isn't a design criteria, because it's always getting warmed. When you're designing something with the intent of being a heat pump heat sink for all humidity climates, you design it with avoiding icing as a key criteria, and you can achieve that need at the expense of additional heat sink size, wider thicker fin spacing, and a few other tricks.

True. And one of the fewer other tricks is a reverse valve to turn the heat pump around briefly to melt the ice. My test "turned around" window air conditioner has none of the features you mentioned. It was a true air conditioner and that's likely the reasons for it to ice up quickly.

 

[LeftieBiker]

Did you read specifically that the heat is coming from the air at those temps? Because home heat pumps do provide heat in that range, but at the colder end it comes from built-in resistive heating elements, not the air. Maybe my knowledge is out of date, but I find it hard to believe that they can scavenge enough heat from the air at those temps...

It's just physics. You can extract heat from air at any temperature right down to absolute zero (-273 deg C, -460 deg F) using a heat pump if you use a suitable heat transfer fluid. The -18 deg C limit for currently available heat pumps (including that in the Leaf) is solely a consequence of using a working fluid that is safe and doesn't damage the atmosphere if it escapes.

Our use of 0 deg C for freezing point, or 32 deg F, is just a consequence of us adopting an couple of oddball heat measurement systems. The point where air has no heat energy at all is 0 deg K, absolute zero. At any temperature above that there is useful heat that can be extracted by cooling the air down further. It makes no difference whether you drop air at 10 deg C to 0 deg C, or drop air at -30 deg C to -40 deg C, you will get the same amount of heat energy out of it.

Oh, I understand that 0 degrees C isn't absolute zero! I guess my knowledge is just out of date. If the Leaf's heat pump can provide usable heat down to 0 degrees F, then that's great news. It will, however, still require another heat source in the coldest markets. You don't want to get into one in a -5 degree F parking lot and get a "Sorry, no heat!" light!

 

[SamTexas]

You don't want to get into one in a -5 degree F parking lot and get a "Sorry, no heat!" light!

Just curious: What does the Leaf User's Manual say? It seems like an important enough detail to be included.

 

[liveforphysics]

It will, however, still require another heat source in the coldest markets. You don't want to get into one in a -5 degree F parking lot and get a "Sorry, no heat!" light!

You still get all the heat going into the system electrically, in a worse case you're a lower power electric heater, in >99% of places people live >99% of the time you've got a more powerful more efficient heater. If you live in Fairbanks Alaska or North Dakota or something, it's not the right car to buy. If you live nearly anywhere else you're going to be fine.

 

[GodlessCommie]

Typed this for my G+ friends. A lot of it is trivial for you guys, as you already drive on electrons, but I hope you'll find something interesting:

One year ago today I took a plunge and traded my TSX for the all-electric Nissan Leaf. It was not an easy decision - keeping a well-running older car is always better financially, and even though I was following the battery technology for awhile (or maybe because of that), I was not a 100% sure it would work out.

I'm happy to report that the first year of driving was extremely uneventful. I didn't get stranded, didn't run out of juice in the middle of the trip (although I had to take my wife's car to work on two occasion because I forgot to plug mine in the night before). The car drives just like any other, only better. Very quiet, no vibrations, very linear acceleration and deceleration. Love the heated steering wheel and listening to Pandora through Bluetooth.

Everybody is asking about my electric bill. It went up ~$20/month. I used to spend ~$100 a month on gas. Dominion switched us to an experimental tiered rate plan, so I charge at 5c/kWh, but my peak rate is 16c. It works out a tiny bit to my advantage, maybe $5/month compared to the flat rate.

Surprisingly (or not) the Leaf changed the way I drive. I used to drive stick, traffic lights and traffic jams were annoying me beyond reason. I almost felt how the clutch was wearing out. Now I almost feel how the energy from slowing down gets saved in the battery. I started picking more direct routes on slower streets, and the stress level went well down for me. Driving is almost a Zen experience now.

The field changed a lot in this year. There's not only an excellent Volt and mediocre iMev that were selling back then, but also Prius Plugin, Ford C-Max Energi, electric Honda Fit and Ford Fusion, Toyota RAV4 and BMW ActiveE. Almost every manufacturer has either a plug-in hybrid, or a fully electric car (although not all of them are available nationally, and some can only be leased). Deals also became better, especially leases on Volt and Leaf, sometimes down to $200/month. So if anybody is on the fence - the time to start driving on electrons may very well be now.

 

[o00scorpion00o]

I would love a Leaf, but currently I wouldn't make my 85 ish mile round trip. I would save around 4000 Euro's a year over the Prius at 60 mpg because of the High petrol prices here and the high road tax and because of less maintenance.

That would pay back a Renault Zoe in 4 years, or Leaf in 6 years, Renault give free battery rental for the first 2 years.

The whole problem is not knowing how long the battery lasts or how much it will cost to replace. Doing 25000 Miles a year could mean a new battery after 4 years or less. It's not a problem with Renault because you rent the battery, but if I add up the cost of the battery rental over 4 years to cover my mileage it would cost 8100 Euro's so it actually ends up costing as much. But it's the uncertainty of replacing the battery in a Leaf is the main problem.

 

[dnmun]

why could you not make the round trip? you could charge at work or at a charging spot during the day, and make it back with no trouble.

it is charging spots that are needed, not humongous battery packs.

 

[o00scorpion00o]

why could you not make the round trip? you could charge at work or at a charging spot during the day, and make it back with no trouble.

it is charging spots that are needed, not humongous battery packs.

Exactly what I've been saying,

Well there is no fast charger on my route, and I can't currently charge at work. But if I could then the problem would be sorted. I need at least 25 kw/hrs to drive the 85 miles because of the reduced range in winter and the heater. I don't know what extra range you would get out of the 2013 leaf with the heat pump. I guess we'll have to wait and see.

Wish they would answer the end of life battery questions.

 

[Toclofane]

The Leaf is a great car and really deserves more attention.

 

[Xrain]

It will, however, still require another heat source in the coldest markets. You don't want to get into one in a -5 degree F parking lot and get a "Sorry, no heat!" light!

You still get all the heat going into the system electrically, in a worse case you're a lower power electric heater, in >99% of places people live >99% of the time you've got a more powerful more efficient heater. If you live in Fairbanks Alaska or North Dakota or something, it's not the right car to buy. If you live nearly anywhere else you're going to be fine.

IT ISN'T THAT COLD HERE... :wink:

Took these this morning.

Yea I think most of the EV's up here that I know of use resistive heaters. As well as some heaters in the pack to plug into the wall when not in use.

There are some that use Heat pumps in their house up here, but often times they circulate water through the ground, though I think there are a few that use air circulation. Haven't talked to any personally however. It would be interesting to see how a leaf would perform up here. My Nissan pickup truck hates anything below -30F. My heater in my truck stops putting out all that much warm air at around -40.