Give up charging during winter?

It was 8 this morning, but the charger cord outside was still nice and flexible!

 

Any electricity you use will provide a greater benefit to the gas used. That has been overwhelmingly confirmed by those who drove their Prius PHV in the winter, leaving home with full charges every morning. When the engine runs, that heated coolant will circulate to provide warmth for quite awhile, allowing the EV drive to be taken advantage in the meantime. MPG clearly shows the resulting gain.

Electricity use will also help reduce pollution, which is worse during the winter. So whether it saves money or not, there's still a win in return. Leaving Prime plugged in will take advantage of the battery-warmer too, which reduces impact from the cold.

Have you looked into time-of-use discounts from your electricity provider? I had a sub-meter installed. That dropped my price paid for overnight charging to 6.74 cents per kWh.

 

Confirmed during my two week visit to Ohio in November with our PiP. We had some highs in the 20s the 1st week and I was still getting good results just driving in EV mode and letting the engine run when it needed to to provide heat. I gotta think the Prime is way more efficient.

 

I recall when I was being recruited for a job in MN and took one look at all the cords dangling from the front grill of the cars....

New Bern is a nice town, but on the coast with rising tides....old houses, history, boating, pretty upscale.

I live pretty much in the middle of NC and any route I've plotted (NC mountains, SC, DC, PA, etc) for trips I've actually taken just doesn't work well with an EV. Which is why I drive a Hybrid. I like starting out in the AM with 400 miles (range > bladder) and the ability to refuel in as much time as it takes for one of us to take the comfort stop with no deviation from the planned route. I can live with every two hours or so but the worry is enough of the right type of charger in proximity to my route and the time to charge.

 

here is the excel to help you out put your cost etc and you will find out if it worth charging or not

 

Sometimes the $$$ shouldn't be the deciding factor.

 

I agree with the general advice to use EV mode as much as possible. Remember that heat pumps use much less energy than the electric resistance heat that was used in early electric cars. It's not worth burning gasoline just for heat; save it for when you are out of electricity.

However, intelligent use of the electric seat heaters and the steering wheel heater if you have one is also more efficient than heating the whole interior. I keep the cabin heat set for about 65F, and wear a light jacket, and use the steering wheel heater from time to time if needed. My passenger uses the seat heater in the same way.

If you have the remote climate feature, then by all means used it (always with the car plugged in), because even at low temperatures the heat pump in the Prime is more efficient than burning gasoline for heat. The coldest temperatures I've had so far were in the upper 20s (F); I selected "last in-car setting" (65F) and "Front Defrost". then pressed "turn on climate". The car spent about 10 minutes heating, then about 20 minutes more re-charging. The whole process used 0.35 to 0.38 kWH, which cost me about 8 cents. When it gets colder, I may try the "max heat" option.

See How does the heat pump work in a Toyota Prius Prime plug-in hybrid? | PriusChat for technical information about the Prius Prime heat pump.

 

Once it gets down the teens and below the car will start the ICE whether you want it to or not.

 

hope that helps to determine if it worth charging or not, depending on your cost of gas/electricity.

 

I think a lot of people are probably not really touching base on what the OP actually means here. There are a couple different factors to remember when using a plug-in hybrid. I should probably go ahead and make a list to get my talking points in order.
1. Batteries have a variable charging efficiency affected by heat.
2. Batteries have a usable charge capacity which is effected by heat.
3. Charging speed and time also have an effect on charging efficiency.
3. Electricity cost is Very High so system efficiency needs to be very high.
4. Electricity is more expensive in the NE and more expensive in the winter.
4. ICE engines run on relatively cheaper fuel but are still effected by cold weather
5. Both energy sources come directly/indirectly from non-renewable energy so neither is tech. green.
5. ICE Pre-heating Devices/methods.
6. HVAC use in Hybrids has more of an effect on hybrids than normal cars.

Alright, so you have some options here. It's actually pretty complex to figure out if its worth it at the moment to use electricity instead of gasoline and with gasoline prices so much lower now than when the car came out it is an even harder decision (the reason I bought my Prius hatch last year vs a plug-in hybrid). But for the variables of actually getting the energy to the battery efficiently and retaining it, you really wanna be at a pretty mild temp. So if you can charge a battery in say your heated to some degree garage you for sure want to do this. I don't have the exact efficiency numbers but the more extreme to a degree of temperature the more the charging efficiency goes down and inputting the same amount of energy actually gets less charging as a result. So ideal optimal is somewhere between 59F (15C) and 95F (35C) and for our case when you get below the range the battery chemistry gets pretty sluggish and it actually limits the point of capacity at which the battery can charge to without reducing life. So if you can warm the battery up to somewhere closer to these values while it charges overnight you can actually get the battery to accept more charge. Also, level 1 charging is somewhere like 76% efficient, and level two charging is something like 85% efficient when charging for longer periods of times but the numbers are much lower when only charging for a short period of time so try not to short charge it's not very efficient. So say if you went home for your lunch break and charged your car with a level one charger in the cold for thirty minutes you lost so much energy going to the battery it was probably better for you to have just faced the diminished battery capacity and used gas if you ran out of battery at the end of the day. Also, electricity is relatively expensive across the United States but much more so in NE (something like 40% more expensive than my area) because their grid can hardly support what they have and they have to buy power from outside sources to cover surge use and other times when they fail to produce enough. So especially in the winter (or summer both temp extremes hvac use is about 45-50% of most home energy use) if say their power source they get their energy from rises in price (coal or nat. gas goes up for the power plant) or grid demand goes up (mostly from people being indoors more and using more electricity) and they have to buy from a more expensive source it reflects in the cost for the month. That's why the kW hour price is never the same from month to month. So I'm not really sure of the exact prices in your situation since I just know gas and electricity is pretty high in that area compared to AR. A good solution if you had a garage would be to pull the car in the garage so your battery and your engine (my garage isn't even heated but by default in the winter it's about 20F warmer than ambient) by default starts out say 20 degrees warmer. Then I would definitely try to get a level two charger for charging and only charge over night for long periods of time. You could also get a block warmer installed. So say if you did want to use the engine because it ended up being cheaper to use electricity from your house to heat the block up to increase efficiency you could set a plug timer with your smartphone and start block warming for an hour or two prior to your commute and that combined with the garage you could start to say 70 degrees warmer than having your car sit in the driveway. Also since most portions of the Prius are more efficient (ex: higher efficiency drivetrain that the ICE setups) than standard cars the HVAC actually consumes more pieces of the pie. And when you only have an 8.8kWh battery (gal of gas ~33.7kWh, I think the epa uses this number as well) which equals .26 gallons of gas you can see the dang hvac really will use all of your battery pack compared to ICE SETUPS (think cheap fuel source and less efficient setups you don't really notice the HVAC impact as much) so try and only use the PTC heater for defrosting the window, get a seat heater, wear a jacket, and get one of those aftermarket steering wheel heaters.
So that the synopsis. Sorry, its wordy.
If you wanted to go into more depth you can try and charge more efficiently and get a kill-a-volt ot some sort of volt/amp meter/ recorder and see how much energy you are putting into the charger and how many miles you're actually getting out of that energy so you can see your cost per mile and compare it to cost per mile of the gasoline engine.

Heres an example of my situation:
For November (on my 8mi round trip work commute and Walmart runs)
Gas cost: $2.089/gal (right off the bat gas is already 47% cheaper based on 33.7kWh per gallon)
Electricity cost: $.0912/kWh
Gas cost per mile - 2.089/49mpg= $0.04263/mi
Guesswork:
https://www.veic.org/docs/Transportation/20130320-EVT-NRA-Final-Report.pdf (page 9) (actually a good read)
Charging efficiency I'm assuming (w/o temp consideration): 86.4%
8.8kWh/.864= 10.185kWhs of electricity needed to charge the battery 8.8kWh.
95mpge (gas equivalent...) for 2012 PiP
Alright, final equation.
8.8kwH*$.0912/kWh*(.864)^-1 *(33.7/8.8)kWh= $3.557 per gallon equivalent / 95mpge = $.03744/mi electric cost per mile
So I'm assuming at absolute worse that you have normal distribution electricity and gasoline prices like above so the electric cost per mile ends up being closer to what a standard non-hybrid is. (I've heard horror stories from my boss who moved to AR from PE who said surge prices and expensive electricity prices in the north almost made it not worth it to drive an electric car at certain times in the year).
So it would be like 49mpg vs 55.8mpge (or 45.5mpge if you decided to level 1 charge for 45 minutes during your lunch break). (so yearly you don't save much in fuel cost)
So if you're an idiot and use a level one charger and don't let the charger charge the battery a large portion at once I can definitely see where in combination with the cold weather the cost of charging the battery, using the battery to run around would actually not be cost effective.

Sorry for the term paper but I think the concept is interesting. As electric cars make advances, gasoline suddenly got cheap again, inflation happened and made gas prices seem even more normal, and now mazda and others are saying the they have a car coming out next year that can run hcci with a supercharger that can run super high diesel like efficiency at cruise or run standard power cycle gasoline maps at high load to zip around like a normal car to boost ICE efficiency numbers to diesel like numbers without the 25% increase in fuel cost which will make it even harder to decided to buy a plug in electric car of some sort. Imagine a hybrid car with an HCCI engine... and how much more competitive it would be with pure electric cars cost per mile wise.

 

i'm not following you, can you expound on that a bit?

 

Synopsis: Electric range and Charging efficiency are hugely variable and electricity is expensive compared to gas. Try and record the electricity going into the battery (like a gas pump does gas) with a clamp and see how many miles you're getting out of each charge. Then find your cost per mile using the electric mode only and compare the two modes. Above also mentions efficient ways to charge and inefficient ways.

Also forgot to mention that as the car gets further out of the optimal temp range the battery loses charge at a faster rate than normal (think money slowly dissipating into inexistence), but you will see all of that reflected at the clamp.

 

hayden55, your gas prices are way too cheap.here in Seattle its about $2.80 at Arco, Chevron is closer to $3.00 for 87 gas.

electricity rate in WA is cheaper compare to other states 7.75¢/kWh because of the Grand Coulee Dam we have here on theColumbia river.

 

Wow, that is interesting to hear. Makes the electric car perspective even more interesting in your area. Yup, everything in Arkansas is pretty cheap for the most part especially with an emphasis on how cheap gas/diesel/natural gas is in the south versus the more overpopulated areas in the far west and north east.

 

walmart effect.

 

I can't really follow your post, but 49mpge just doesn't fit even close to what i'm seeing. Our electric prices are .12 kWh, my commute is 75 miles (total), climate is warmer, but we get into the 30's at night right now, and with a full charging, I get 90 mpg average on my commute, so there's no way mpge can be less than what i get in pure hybrid mode. I get close to the 55mpg if I go hybrid alone...

I figure my electricity costs around half of gas (We're at $2.20 right now)...

 

If you are getting 90 mpg average on a 75 mile commute, you are using 0.833 gal of gas.
If in HV mode you get 55mpg, then the 0.833 gal of gas is taking you about 46 miles and the other 29 miles are EV.

With a 6.3KWh charge at $0.12/KWh you are spending $0.75 per charge and going 29 miles or 2.6 cents/mile in EV mode.
At $2.20/gal you are going 55 miles in HV mode or spending exactly 4.0 cents/mile in HV mode.
Looks like electricity is costing you the equivalent of $1.43/gal...Electricity cost you about 2/3rd what it cost to use gas.
Very nice.

 

Yeah, I've been really happy with it and it's a bit better than I thought it would be. On the very coldest days, I expect it to not be as good, but these moderate day numbers more than make up for it to me. I also like the way it drives under EV too and wish my employer would get a charger!

 

Our electricity is 8.58 cents per kWh for first 660 kWh, and 12.87 cents above that. We're typically completely in the lower level (last month consumption 490 kWh).

Gas fill up a couple of days back was $1.31 per liter.

(All Canadian dollars)