Is Battery Temp Reason for Low MPG @ Lo Temp?

msilverb · 02-19-2008, 04:20 PM

I wonder whether low temperature short trip MPG could be improved if a system was included to raise the battery temperature before driving. One possibility is an AC plug in connection and a timer to turn it on sufficiently early in the morning.

**efusco** · 02-19-2008, 04:31 PM

It's certainly a factor, but there are multiple factors in the cold on short trips. The battery takes a very long time to warm up and when it's really cold the HV capacity is reduced and does impact FE.

diamondlarry · 02-19-2008, 04:44 PM

It seems that any temp below 25F for sustained periods will cause EV mode to not be available. It also seems to cause the ICE to come on if you even think about touching the gas pedal.

**efusco** · 02-19-2008, 04:50 PM

Quote:

Originally Posted by diamondlarry

It seems that any temp below 25F for sustained periods will cause EV mode to not be available. It also seems to cause the ICE to come on if you even think about touching the gas pedal.

Hmmm, that's not my experience....unless you mean the battery temp specifically. But as long as the battery and ICE are warm I can EV, glide, etc. almost like in warm weather no matter the outside temp.

jayman · 02-19-2008, 05:28 PM

In very cold weather, you will experience improved heater performance and fuel economy by using the EBH and by blocking the front grille

diamondlarry · 02-19-2008, 06:54 PM

Quote:

Originally Posted by efusco

Hmmm, that's not my experience....unless you mean the battery temp specifically. But as long as the battery and ICE are warm I can EV, glide, etc. almost like in warm weather no matter the outside temp.

Sorry. Yeah, I was talking about battery temp. When my car is in the garage overnight with the EBH plugged in, I have full use of EV mode whenever I want it. When I'm parked at work and the car gets an 8 hour cold-soak, I quite often never get EV mode even after over 15 miles. I do however, get to glide once the coolant reaches 155F no matter how long the car has been in the cold.

msilverb · 02-21-2008, 04:19 PM

The comments don't relate directly to my question. I live in CT and during the winter mostly make short trips. When the temperature is 32F and below I average less than 38 MPG. When it is about 38 and above I average 43 MPG or higher. This seems too big a change to be the result of the control system warming up the catalytic converter. It would be easy to pre-heat the battery with a thermostatically controlled heater while it is in my garage. Do you guys think this would help? Another question is does an EBH raise the battery temperature?

jayman · 02-21-2008, 07:38 PM

Quote:

Originally Posted by msilverb

It would be easy to pre-heat the battery with a thermostatically controlled heater while it is in my garage. Do you guys think this would help? Another question is does an EBH raise the battery temperature?

No, the EBH does not affect battery temp

I would think it easier to heat the garage itself than just the battery pack. I used to have a condo with heated underground parking, now I have a 1,348 sq ft home with heated attached garage.

It's a Reznor gas heater in the garage. Appears to add about $45 to the gas bill in bitter cold temps, with the heater set at +50 F. Very nice to hop in a car without scraping frost off, just drive off

02-19-2008, 04:20 PM	#1
msilverb Junior Member Join Date: Feb 2008 Location: Westport Posts: 2 My Car: 2006 Prius Model: Package: #5 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Is Battery Temp Reason for Low MPG @ Lo Temp? I wonder whether low temperature short trip MPG could be improved if a system was included to raise the battery temperature before driving. One possibility is an AC plug in connection and a timer to turn it on sufficiently early in the morning.

02-19-2008, 04:31 PM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 19,618 My Car: 2004 Prius Model: Package: #9 Thanks: 215 Thanked 870 Times in 505 Posts Friends: 47	Re: Is Battery Temp Reason for Low MPG @ Lo Temp? It's certainly a factor, but there are multiple factors in the cold on short trips. The battery takes a very long time to warm up and when it's really cold the HV capacity is reduced and does impact FE.

02-19-2008, 04:44 PM	#3
diamondlarry EPA MPG #'s killer Join Date: May 2007 Location: Elkhart, IN Posts: 559 My Car: 2007 Prius Model: Package: #5 Thanks: 1 Thanked 10 Times in 9 Posts Friends: 7	Re: Is Battery Temp Reason for Low MPG @ Lo Temp? It seems that any temp below 25F for sustained periods will cause EV mode to not be available. It also seems to cause the ICE to come on if you even think about touching the gas pedal.

02-19-2008, 05:28 PM	#5
jayman Senior Member Join Date: Oct 2004 Location: Winnipeg Manitoba Posts: 13,430 My Car: 2004 Prius Model: Package: B Thanks: 220 Thanked 581 Times in 449 Posts Friends: 16	Re: Is Battery Temp Reason for Low MPG @ Lo Temp? In very cold weather, you will experience improved heater performance and fuel economy by using the EBH and by blocking the front grille

02-21-2008, 04:19 PM	#7
msilverb Junior Member Join Date: Feb 2008 Location: Westport Posts: 2 My Car: 2006 Prius Model: Package: #5 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: Is Battery Temp Reason for Low MPG @ Lo Temp? The comments don't relate directly to my question. I live in CT and during the winter mostly make short trips. When the temperature is 32F and below I average less than 38 MPG. When it is about 38 and above I average 43 MPG or higher. This seems too big a change to be the result of the control system warming up the catalytic converter. It would be easy to pre-heat the battery with a thermostatically controlled heater while it is in my garage. Do you guys think this would help? Another question is does an EBH raise the battery temperature?