bwilson4web
Posts: 689
Joined: Fri Apr 29, 2016 11:59 pm
Location: Huntsville, AL

The AAA Cold and Hot Weather report

Sat Feb 09, 2019 12:38 am

Here is the formal report: https://www.aaa.com/AAA/common/AAR/file ... Report.pdf
  • Key Findings:

    1. In isolation, hot and cold ambient temperatures resulted in modest reductions of driving range and equivalent fuel economy. Driving range and equivalent fuel economy reductions slightly differ due to the temperature dependency of both the recharge allocation factor (RAF) and battery discharge capacity.
    • a. On average, an ambient temperature of 20°F resulted in a 12 percent decrease of combined driving range and a 9 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
      b. On average, an ambient temperature of 95°F resulted in a 4 percent decrease of combined driving range and a 5 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
    2. HVAC use results in significant reductions of driving range and equivalent fuel economy.
    • a. On average, HVAC use at 20°F resulted in a 41 percent decrease of combined driving
      range and a 39 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
      b. On average, an ambient temperature of 95°F resulted in a 17 percent decrease of combined driving range and an 18 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
    3. Depending on ambient temperature, HVAC use results in a significant monetary cost increase.
This looks to be a serious study with attention to detail. I'm still reading it. However, it also shows that "pre-conditioning", heating in the winter and A/C in the summer, can make a significant improvement. The least efficient way is to jump in the car without taking the 20-30 minutes to get the car and cabin ready for the weather conditions.

Bob Wilson
20k/27k mi 2014 BMW i3-REx
10k/10k mi 2017 Prius Prime

frictioncircle
Posts: 29
Joined: Fri Nov 25, 2016 11:23 pm

Re: The AAA Cold and Hot Weather report

Mon Feb 11, 2019 1:26 am

Excellent post, bwilson4web, thank you for sharing!

At 60+ pages it's going to take a bit to get through this but it looks like the Auto Club did a very good job here.

websterize
Posts: 506
Joined: Sun Sep 07, 2014 3:39 pm
Location: USA

Re: The AAA Cold and Hot Weather report

Mon Feb 11, 2019 11:59 am

bwilson4web wrote:… However, it also shows that "pre-conditioning", heating in the winter and A/C in the summer, can make a significant improvement. The least efficient way is to jump in the car without taking the 20-30 minutes to get the car and cabin ready for the weather conditions.
Just a clarification (and you probably already know this): Pre-conditioning the high-voltage battery to optimum temperature only happens when you set a departure time in the car. To warm/cool the pack to this temperature, and to achieve maximum range, you must set departure time at least three to four hours in advance of heading out. And conditioning of the HV battery occurs only with a Level 2 connection.

Pre-conditioning from the smartphone app or the key fob heats only the interior cabin.

jadnashuanh
Posts: 4422
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: The AAA Cold and Hot Weather report

Mon Feb 18, 2019 1:42 pm

Also, you can precondition the cabin whether you're connected to an EVSE or not...it's more efficient if you do this while still plugged in. And, if you do set a departure time, make sure the cabin preconditioning option is also set, or it will just condition the batteries.

If you're stopping for a short while on an errand, you might find it also saves a bit to click the box to keep the cabin conditioned (only runs about 20-minutes, so good for a quick run into a store) rather than letting the cabin heat soak in the summer or chill a lot in the winter. That action may be a tossup, though.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

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