Do you think winter's effect on EV is given enough attention?

Last winter Consumer Reports did a prelim report on Volt and reported 2 mile/kWhr versus the normal 3 mile/kWhr in winter. I then used this number to calculate that represents quite a bit of fossil fuel burned at the power plant. My number was so ugly I will not repeat it here. Believe Leaf may not take as bad hit (at least last years version).

 

The poster in that thread is in Arkansas (midwest US not terribly far north) but apparently he'll have weather like this 3 or 4 months worth out of each year. Ironically the averages for my city in Tennessee are lower than his and I don't consider it cold here.

But as to what I think about the cold and EV use, I think some leaf owners need to readjust their thinking pattern on charging.

Using the 120v charger instead of the 240v charger will charge slower but will ensure the battery is warm when you unplug it in some scenarios. A full charge is listed in the wiki as

• Level 1 (120V) - 18 hours
• Level 2 (240V) - 7 hours

But you may not be driving to 0%. So say you make it home at 20% charge and you want to get to 80% charge, the net charge needed is 60% or about 10 hours on Level 1 or 4 hours on level 2.

If you start charging as soon as you get home at say 7 PM the L2 charger will leave the battery pack to cool down after it's done charging in 4 hours so if you leave for work at 7 am it has 8 hours to cool off.

Take that same scenario with the L1 charger and it isn't done charging until 5am and only has 2 hours to cool off. Go one step further start it at 20% SOC at 7PM and request a 100% charge cycle with the L1 and at 7am it'll still be charging somewhere in the 9x% range (above 90% below 100%). Since charging produces waste heat you'll have a warm battery as you pull away from the house (warmer than using the L2 charger unless you time it just right).

That warm battery will behave better in terms of delivering power on the outward drive away from the house. If you can plug in the L1 charger at work it'll be warm for the drive home but even if you don't the warmer battery will hold charge better on the outward drive giving you better efficiency and getting you to your destination with a slightly higher SOC.

Also, we know 80% charge is easier on the battery but if you only deal with truly cold weather for 2 or 3 months a year just change your habit to ask for 100% charge in the coldest months to offset the heater use.

In short

1. favor the L1 charge rate if it'll get you near 100% charge before you need the car
2. favor 100% charge vs 80% charge in the coldest months

It won't make the hugest difference in the world but it'll help.

 

Oh, and I didn't address choice of EVSEs in that post. There is an in between option for those who got the wall mounted L2 EVSE

see My Nissan Leaf Forum • View topic - Fast Low Cost Charging - All EVSE Questions Answered! for more details

You can choose at the time of upgrade if you want it to charge at 12a * 240V or at 16a * 240V

If you want it to charge faster you can do the 16a option. If you want to make your battery last longer (plan to keep the vehicle years down the road) you can charge at the lower amperage to charge slightly slower.

3.84 kW (240 x 16 amps = 3840 watts, a 16-amp L2 EVSE)
3.30 kW (220v * 15a = 3300 watts "nominal" EVSE description)
2.88 kW (240v x 12a = 2880 watts (L1/L2 EVSE)
1.44 kW (120v x 12a = 1440 watts standard L1 EVSE)

In other words by choosing your EVSE you can charge slow, medium, fast or low, medium, high.

I'm suggesting using the 12a L1 or 12a L2 vs the Nissan spec L2 or the 16a modified L2 as the slower charging will be easier on the battery long term and could help you keep the battery warm in winter conditions.

 

It's time to bring back gasoline powered heaters for cars to increase EV range in the winter. Southwind heaters were good heaters.

 

Ok, I'm a little confused here. You heat your garage with fossil fuels, but are concerned about a slight winter time hit to your EV numbers. Wow!

 

The range reduction due to colder temperatures has nothing to do with the battery.

The type of battery in the Leaf and Volt has an optimal operating temperature range of 0° F to 100° F. Not like a NiMH or NiCad battery that prefers to be at exactly 68° F all the time.

The reason for reduction... The owners are using the heater more and probably driving a bit more aggressively in order to either use the heater less or to get out of the cold weather faster.

After preheating from shore-power, I noticed that the heater will draw about 1.5 kW continuously with the occasional bump to 3 kW in my Leaf. Since my commute takes just over an hour (one way), that's about a 10% reduction in range. I've gotten a lot better about pulsing the heater as necessary manually in order to keep things comfortable and have reduced my additional consumption to around 5%. With some luck, the seat heaters I'm ordering next week will allow me to reduce my additional consumption to around 2% (including the seat heaters).

 

He runs his EV on fossil fuels, too

 

My back of the envelope calc says that 4 season climates will end up with annual energy consumption up to (1.5*4 + 8)/12 = 17% higher than they might estimate from EPA numbers, since that test does not have a cold drive cycle.

Smart PiP owners are going to rip the Volt (or a pure EV, for that matter) in winter driving by using the CHP ICE judiciously.

 

I'm a Volt driver. I've seen about a 20% drop in range since I had to start using the electric heater. (27-36 mi instead of 35-45 miles).

Pre-heating the cabin before unplugging in the morning makes a world of difference. Once the cabin temp is comfortable the system doesn't have to work as hard to maintain it compared to what it has to do to actually change the temp into the comfortable band. I also find the heated seats key in my own comfort without too much power draw (about 6% of climate system power output).

In the afternoon I find all the glass and generally black interior tends to have the interior temp significantly higher than the ambient when I get in.

To be honest, my main concern for this winter is devising some way to cover the plug so a snow or ice storm doesn't freeze the EVSE in place.

 

We know the resistant heater in the leaf is the biggest draw. Ignore it for a second.

You suggest that the leaf battery pack is practically the same efficiency at 70F it would be at 30F. I disagree with that but lets also ignore that for a second.

Do you know that the leaf battery pack self discharges when the charger isn't active and the EVSE doesn't have any sort of trickle charge mode to maintain charge?

Do you know that Leaf owners have set their car to charge to 80%, gone to bed and woken up to find it was closer to 70% than 80%?

Charging at a lower rate so that it will still be charging when you wake up not only is less harsh on the battery long term, not only keeps the battery warmer in the winter, it also keeps the battery for self discharging during the period between the L2 charge ending and you actually powering up the vehicle.

And of course the big one of charging to 90%+ if you can vs stopping at 80%.

Again self discharge is only worth a few percent but when we are talking about winter usage I'm saying all these couple of percent here and there add up.

Slow longer charge targeting 100% vs 80% on a faster charge could

1 provide longer battery life in terms of years / charge cycles
2 keep the battery warmer in winter usage
3 reduce non charging time, reducing self discharge
4 actually give a higher state of charge when you leave the house if your usage/charging patterns allow.

And I'm not saying you have to do 100% of your charge at 120V x 12a. If you know you are at the edge of your range / charge time window you can charge at L2 rate targeting 80% for an hour or two, then go stop the charge process and plug up the L1 and start charging again at the slower rate targeting 100%.

Depending on how good you are at controlling the process you could end up with a higher SOC and a battery that's in better shape to handle the conditions.

 

I would assume Nissan did extensive cold-weather testing, but real-world, average consumer experiences will be interesting. The only winter battery testing I've done is while skiing. The tunes have to go in an inner pocket, or they fade out surprisingly quickly. I hope the same doesn't happen with EVs, because that will just add another excuse for the dinosaur crowd.

 

While we usually take for granted that the ICE 'waste' heat is free, we do know that it really does burn more fuel in winter. And it burns more still when the cabin heat is turned up.

When comparing costs, are folks including the extra fuel the Prius needs in winter? It is not fair to compare Leaf's winter cost to Prius' fair-weather cost.

 

I don't know about you but for me at less than 10c a kWh (electricity is cheap in my state) the leaf is so much cheaper to use the cost per mile isn't an issue.

If I could afford to buy a new car and if I could live with the range limitation the Leaf is the cheapest per mile cost (if you drive it regularly)

I'm in a used Prius and will be for the foreseeable future but I hope someday to be able to grab a used Plug in Prius or Nissan Leaf that someone treated well and use it.

I don't think it matters if the Prius drops 20 MPG in the winter vs summer and the Leaf drops range in the winter. I don't think the cost differential will be the biggest factor.

I think range is the one thing people worry about and have to manage.

 

Mine consumes about 10% extra in winter -- see my two year mpg graph -- and I don't even have a 'real' winter climate. Other than extra rain.

During my city commute, the ICE spends a lot of time turned off, and the ScanGauge often reveals a coolant temperature drop of 30-40F, despite grill blocking. In winter, cabin heat cools it off much faster, and often forces the ICE to fire up for heat while I sit at lights. Therefore I often use no heat, or turn it off at lights to allow ICE shutdown. Drivers with 'real winter' will see far worse engine cooling, even with a grill block.

The hardcore CleanMPG hypermilers see this extra winter fuel consumption in standard ICE vehicles too, and go to great lengths to minimize heat losses.