How to Improve Winter MPG's

[ptjones]

With Winter here now, temps in the mid 30's it is time to cover all the grills to conserve as much heat as possible.  BRRR :sad:  Yesterday I got 63mpg going to work with 46*F and some HVB charge and today only got 40.7*F with 34*F, sleet, rain and no HVB. :sad:

 

Paul

[ptjones]

Yesterday We made our normal trip up to North Atlanta(49mi.) to see our new grandson and see the New Star Wars movie.   I started out and ended up with 53.9 mpg, outside temps 45*F going Up and 35*F going home with 40 mi. FWY and 9 miles, 45 mph City. I did have 5 miles of stop and go HWY construction going( extra 30 min.) up and nothing going home. Better than I would expect given the temps.   You Tube videos up to 4,550 now, Hoping these are helping new members to improve their MPG's this winter. 

[ptjones]

I'm surprised how good my gas mileage has been with temps in the 30's and 40's and about 60% hwy. With 540 mi. on tank and 55.6 mpg Smart Gauge average, I should have another 700+ mi. tank and 54 actual/fuelly mpg.  :) Bottom line is these Mods really work and pretty much anyone can do them. :) 

 

Paul 

[joshg678]

Its been about 14F here, only been getting 45 if i'm lucky

[ptjones]

What Mods are you using? :)

 

Paul

[joshg678]

What Mods are you using? :)

 

Paul

Haha. I have the lower grill covered and the center is taped.

Mileage is much better if I don’t use heat but I like my heat. Usually only set to 68.

The battery drains fast when cold, it’s very noticeable. There’s about a mile stretch I drive on at 40mph and I can always make it when SOC is 54%+ but when it’s cold I only make it half as far on the same SOC. Is drains down to 42 very quickly and needs ICE for a bit to charge back up and then I continue on EV for the last bit.

[obob]

Haha. I have the lower grill covered and the center is taped.

Mileage is much better if I don’t use heat but I like my heat. Usually only set to 68.

The battery drains fast when cold, it’s very noticeable. There’s about a mile stretch I drive on at 40mph and I can always make it when SOC is 54%+ but when it’s cold I only make it half as far on the same SOC. Is drains down to 42 very quickly and needs ICE for a bit to charge back up and then I continue on EV for the last bit.

 

I am noticing with temps in the low teens on shorter trips, even if the temp gauge is like a third of the way up, the system's tendency is to use the engine(ICE) rather than electric, even with high voltage battery gauge maxed out.  It may be because the HVB is still super cold and for some reason it would rather wait for it to warm up.

[joshg678]

There are definitely moments where the ICE kicked on for what appears to be no reason. I haven’t been watching the battery temp but I’m sure it’s colder then the cabin temp.

I feel like at temps that low the cooling can for the battery doesn’t run at all. I would think running it on low would help warm the battery from cabin air.

[plus 3 golfer]

The internal reistance of the HVB at cold HVB temperatures limits the use of the HVB.  So, one will see more ICE operation  at low temps than at high temps.   Internal resistance increases significantly when cold and limits the discharge and charge currents.  So, ICE needs to run longer in cold temps than warm temps to achieve the same level of storage. Likewise, when EV is used (discharging), it's likely that ICE will be allocated more of the torque requirements and run more often in cold temps to supply torque to the wheels.

 

However, the higher internal resistance of the HVB should heat up the HV battery faster and thus, limit the amount of time of the above operational constraints to a great extent. Also, operating lithium ion batteries in cold weather reduces cycle life. My guess is that the operational algorithms take all of the above into account. 

 

Bottom line: FE sucks in cold temperatures especially when the trips are short - ICE cold, HVB cold, and high air resistance (air density).

[plus 3 golfer]

I found this graph below which shows how a Li Ion SOC varies with temperature.  Basically, at low temperatures the usable capacity of the battery declines significantly and depends on discharge rate. So, the algorithms will likely limit the amount of discharge resulting in ICE running more at low temperatures.  The battery symbol gauge may show a very high SOC, but in reality there is very little usable SOC and ICE will run more than at a higher temperature.

 

 

[joshg678]

My trips are usually only 14 miles. Park in garage at night, stays about 50F in there (insulated) unless it gets windy.

Leaving work in the afternoon is bad, usually water temp is ambant. Unless I go out for lunch then it’s usually still above freezing when it’s 20F out.

[ptjones]

I did my normal 7 mi. trip to work and these where the conditions. Garage was 52*F, with oil pan heaters on WT 91*F, HVB temp 52*F and SOC 41%.  Outside temp 21*F, I got 52.8 mpg with 39% SOC. Didn't see HVB temp when I got to work, but when I went to lunch an hour and a half later if was 59*F. Drove 4 miles to lunch and 4 mi. back with 54 mpg too and 47 mpg back, ended up with 50% SOC and HVB temp 64*F. Two and a half hours later HVB temp was down to 48*F with OT of 27*F and SOC was up to 56%. :)

Paul

[joshg678]

It was 9F this am, and my garage was much colder then usual because we didn't drive anywhere the last 2 days so i had a WT of 31F, ICE Fired up right away :(

 

Considering the Oil Pan Heater at this point.  Friday is a High of 12F.  Brrrr

[ptjones]

Not that bad in Atlanta area high 35*F today still Brrr. Using oil pan heater at home and work.  54 mpg/ 50 mi. on this tank so far. :)

 

Paul

[kyledamron1]

Bitterly cold here in Ohio. Temps ranging between 0-25 for the past few weeks. MPG is averaging between 30-50. Very difficult for it to get warm enough to turn off. And even inside my garage, it'll start the engine instead of the silent start. 

[ptjones]

Under those conditions you really need block/ oil pan heaters to have a chance of getting enough heat in the ICE to turn it off. :sad: In my opinion all Hybrids should come with block heaters standard.  

 

Paul

[fbov]

+1

 

I found this graph below which shows how a Li Ion SOC varies with temperature.  Basically, at low temperatures the usable capacity of the battery declines significantly and depends on discharge rate. So, the algorithms will likely limit the amount of discharge resulting in ICE running more at low temperatures.  The battery symbol gauge may show a very high SOC, but in reality there is very little usable SOC and ICE will run more than at a higher temperature.

 

Capture.PNG

Great data. Note the chart is in Celsius; -20C is -4F.

 

We're about to get a spell of sub-zero this week. I remember from two years ago what it's like driving with a cold HVB. This chart shows why sub-zero is a special case, where our EV systems can't function. Note this is for discharge; no charging below 32F. 

 

Have fun,

Frank

[ptjones]

+1

 

Great data. Note the chart is in Celsius; -20C is -4F.

 

We're about to get a spell of sub-zero this week. I remember from two years ago what it's like driving with a cold HVB. This chart shows why sub-zero is a special case, where our EV systems can't function. Note this is for discharge; no charging below 32F. 

 

Have fun,

Frank

That's brutal. :sad:  I don't know if having a heater inside the car is going to help much.

 

Paul

[joshg678]

That's brutal. :sad:  I don't know if having a heater inside the car is going to help much.

 

Paul

I was considering a space heater in front of the car and one inside lol.

 

I do think i will be buying the oil pan heater though.  How long do you leave yours on for Paul?

[raadsel]

I was considering a space heater in front of the car and one inside lol.

 

I do think i will be buying the oil pan heater though.  How long do you leave yours on for Paul?

 

I recall one person, posting on another forum, mentioning that he adapted an electric blanket to sit on top of the battery and keep it warm. I believe he stated he toyed with the idea of a space heater but discarded the idea as there was too much risk.

[obob]

Some winter notes:

 

I have/had a strap on seat warmer.  I was not very careful to keep it unwrinkled.  Well it shorted out and something melted plastic onto my seat and/or the seat was scortched a bit.

 

If I had a garage to keep my car in I probably would check for wind leaks.  If it is an attached garage it has warm walls.  I recently bought an old house and am finding ways to stop some of the cold air leaks.

 

And these external faucet covers seem to work well to stop cooling the pipes in the house or garage: https://www.homedepot.com/p/Hard-Faucet-Cover-1981/204759083

Edited January 4, 2018 by obob

[Bill-N]

 

And these external faucet covers seem to work well to stop cooling the pipes in the house or garage: https://www.homedepot.com/p/Hard-Faucet-Cover-1981/204759083

 

Since we're drifting a bit off topic, I've found bubble wrap held on with bungie cords (or the ever-popular duct tape) also works.

[joshg678]

I put tape over my top grill today, High of 15 Estimated for today.

I think there was a difference, my WT was up to 170 this morning when i got to work, but only got 42mpg.

[ptjones]

This morning at 9AM temps were only 22*F Brrr.   And got 48mpg going 7 mi. to work.  Started with 44% SOC, 85*F WT, garage was 49*F and ended up with 40% SOC.

 

Paul

[SnowStorm]

With Winter here now, temps in the mid 30's it is time to cover all the grills to conserve as much heat as possible.  BRRR :sad:  Yesterday I got 63mpg going to work with 46*F and some HVB charge and today only got 40.7*F with 34*F, sleet, rain and no HVB. :sad:

 

Paul

Hey Paul, will this arrangement work for a grill cover?  When the weather warms up it goes away!