Mpg drop in winter.

[jjackstone]

Originally Posted by oil pan 4

I'm just saying the economy loss we see isn't all due to the internal combustion engine or battery being cold.
For me it takes more power to maintain speed when cold.
So cold tires, cold transaxle oil and increased air density would be shared between gas, hybrid and pure electric.

Excerpts from a Battery University article below.

"All batteries achieve optimum service life if used at 20°C (68°F) or slightly below. If, for example, a battery operates at 30°C (86°F) instead of a more moderate lower room temperature, the cycle life is reduced by 20 percent. At 40°C (104°F), the loss jumps to a whopping 40 percent, and if charged and discharged at 45°C (113°F), the cycle life is only half of what can be expected if used at 20°C (68°F).

The performance of all batteries drops drastically at low temperatures; however, the elevated internal resistance will cause some warming effect by efficiency loss caused by voltage drop when applying a load current. At –20°C (–4°F) most batteries are at about 50 percent performance level. Although NiCd can go down to –40°C (–40°F), the permissible discharge is only 0.2C (5-hour rate). Specialty Li-ion can operate to a temperature of –40°C but only at a reduced discharge rate; charging at this temperature is out of the question.

The driving range of an electric vehicle between charges is calculated at ambient temperature. EV drivers are being made aware that frigid temperature reduces the available mileage. This loss is not only caused by heating the cabin electrically but by the inherent slowing of the battery’s electrochemical reaction, which reduces the capacity while cold."

Full article: https://batteryuniversity.com/learn/...w_temperatures

So, how can we test how much range loss is from the batteries vs. the mechanics and higher air density at colder temperatures?
Maybe someone with a Chevy Volt can weigh in on their cold weather range reduction in EV mode only since those batteries have active cooling and heating. Although the 1500 watt heating element would likely cause some drop in range by itself.

JJ

[Ecky]

Originally Posted by cowmeat

I saw about a 20% decrease this morning when I turned on the heater in the Volt

Poor thing. Did it get below 70 there?

[Isaac Zackary]

I have a block heater and the grill blocked off by a huge percent. (And even at that the engine never has gotten above 186°F all winter, even climbing steep mountain passes.)

But on the other hand I have studded snow tires. I've gotten stuck at least three times and have had to put chains on. And temperatures have gotten down to -30°F quite a few times. Add to that winter fuel blends.

So overall my fuel mileage went south for the winter. Hopefully it will perk back up once things warm up enough to merit putting the all-season tires back on.

[broski499]

I've got a 2008 Prius and I have seen a significant decline in the winter months, even in Southern California. I don't even use the heater. That initial engine warm just kills me.

BTW - how do you like your Niro? For such a big car it seems to get really good MPG.

[mpg_numbers_guy]

Broski499, my mom has a 2008 Prius, and she averaged mid-upper 40s in the winter normal driving + new tires, and high 40s-low 50s now that its a bit warmer.

She has been running new Michelin X-ice snow tires this winter, but inflated to sidewall max (44 or 51 PSI, I forget which). She also runs a nearly invisible upper grille block that helps with warmup slightly.

Keeping your speed below 65 MPH will help, but she doesn't do that (she's not a hypermiler lol).

A dying hybrid battery will lower your mileage.

Winter does take a larger toll FE-wise on more fuel efficient vehicles, especially hybrids.

[broski499]

Originally Posted by mpg_numbers_guy

Broski499, my mom has a 2008 Prius, and she averaged mid-upper 40s in the winter normal driving + new tires, and high 40s-low 50s now that its a bit warmer.

She has been running new Michelin X-ice snow tires this winter, but inflated to sidewall max (44 or 51 PSI, I forget which). She also runs a nearly invisible upper grille block that helps with warmup slightly.

Keeping your speed below 65 MPH will help, but she doesn't do that (she's not a hypermiler lol).

A dying hybrid battery will lower your mileage.

Winter does take a larger toll FE-wise on more fuel efficient vehicles, especially hybrids.

Hey thanks for all this info.

Yeah I have Bridgestone Ecopedia or something like that. I keep them at 50PSI. My lifetime average is 45. My last few have been in the low 40s. I really need to put in some pipe insulation foam to act as a grill block. My daily commute is all city driving, only about 15 minutes.

[mpg_numbers_guy]

Short trips really aren't good for Prius economy, especially in the cold. You could probably run a 80-90% grille block in the winter on those short trips and half a grille block in the summer (depending on where in CA you are; would want to monitor those coolant temps if you do any significant blocking).

Low 40s for 15-minute drives in the winter/spring isn't bad. The average '08 Prius gets 42.9 MPG according to Fuelly.

[Frank Lee]

With any luck soon cold temps will be a thing of the past.