Video: Summer Heat Hybrid MPG Loss Explained

[Shay]

Like many Maverick Hybrid owners, our truck has seen huge mpg drops from winter and spring to the extreme heat of summer. Ours went from a 47 mpg average to 35 mpg average. This video explains the mechanical and design reasons why it's happening and why not to panic that something is wrong.

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[RonFLA]

Very true, Great explanation and visuals of a very complicated sequence of events. I believe there has been much discussion of the traction batterie’s cooling system having difficulty keeping up in hotter climates. The thermal management system kicks in, limiting regen, prevents further EV use, and impacting fuel economy, until temperatures normalize.

Save some gas by parking under a tree. Keep that battery temp. normalized.

Great video, as always! Love the way you outfitted your truck. It just looks FUN!

 

[Gullzway]

Interesting. No change in my mpg from March(60-70s) until now(104 today.)
Still 43 mpg average per tank.

 

[Shay]

Interesting No change in my mpg from March(60-70s) until now(104 today.)
Still 43 mpg average per tank.

Strictly city mpg or a mix?

 

[Gullzway]

Strictly city mpg or a mix?

Probably 70/30 city/highway.

 

[Shay]

Probably 70/30 city/highway.

That's why it's not affected as much or at all. A mixture allows for a more normal cycle of coast regen and travel recharge of the battery. The video is based on strictly city mpg performance.

 

[WesM]

Interesting. No change in my mpg from March(60-70s) until now(104 today.)
Still 43 mpg average per tank.

Same here, its basically the same mpg of around 43. My max temps are around 98 with a heat index of 105 and I crank that AC up full blast.

My commute is mixed driving of about 40% at 70-80mph speeds, about 40% at 50-60mph speeds and about 20% in stop and go traffic. 110 miles a day.

 

[8211badger]

Nice explanation and an interesting watch. In the colder climates it's basically the same situation in but in reverse for winter time. I'm getting 40 mpg per tank now in the summer but will probably only get around 34 in January when the engine has to run more to keep things warm.

 

[DryHeat]

It's about 5 degrees cooler down here in Tucson and I've only lost about 3 mpg in the heat.

But... part of the difference may be that my driving patterns (and my city) don't result in as much time stopped in traffic as you probably spend in Phoenix.

My guess is that the time spent stopped in traffic is a big factor for MPG. When it's nice outside and the AC isn't running the hybrid uses very little energy when it is stopped, so you're not really losing anything. But when the AC is cranked up full blast, it just keeps draining the battery and firing up the ICE while you sit there.

 

[DesertSweat]

I feel almost all the loss can be attributed to AC usage.

Unless the battery starts getting too hot and then it will limit charging and discharging to keep temps down as I've experienced. But there's very few people who will experience this, let alone notice it.

But hey, we probably still have the advantage in AZ. Once cooler weather rolls in we won't be needed heat like other states.

 

[Harleystreetbob]

Interesting. No change in my mpg from March(60-70s) until now(104 today.)
Still 43 mpg average per tank.

Same here!

 

[MLA62563]

Interesting. No change in my mpg from March(60-70s) until now(104 today.)
Still 43 mpg average per tank.

Same for me. In strictly city traffic, I'm currently matching the best mileage I've ever achieved. (44-ish...the readout is usually 1-2 MPG high.) I leave the AC on at 75 at all times. Temps here have maxed out mostly in the 90's for the last couple of months...so I think the big drop is probably only triggered when you get well north of 100 degrees. And as has been mentioned, driving patterns surely play a part as well. There's a lot of stuff in play.

 

[Falcon first]

Our driving is all city, 92-98 degrees and we have lost 2-3 mpg since May. My wife drove round trip to Cincinnati in June 1,000 miles round trip and got 39 mpg which is about what we are getting in city driving now with higher temperatures.

 

[davnau]

Like many Maverick Hybrid owners, our truck has seen huge mpg drops from winter and spring to the extreme heat of summer. Ours went from a 47 mpg average to 35 mpg average. This video explains the mechanical and design reasons why it's happening and why not to panic that something is wrong.

I've noticed my mileage in July where I live is lower than when I first got it in June and temperatures were more moderate.

This also explains an "anomaly" in the Consumer Report Ratings & Specs section of the updated report. They show 33 MPG City and 39 MPG Highway results for their Hybrid test. That seemed exactly backwards. But the Hybrid was tested significantly later and thus in warmer weather than the EB, as a separate test on a separate truck. If they did the Fuel Economy test for their Hybrid on a hot day, then this all makes sense. Since this report was just recently updated, that was likely the case,. If the test has been done on a 65 degree day in the Spring, the results would likely have been different.

Also means that on a cold winter day, the engine is always running more to keep the battery warm through the heat exchanger that is part of the exhaust system.

It would be interesting to show a plot of MPG vs temperature over say, -20 degrees to +115 degreed F, of actual test results with a Maverick Hybrid. I think it would be kind of a bell shaped curve, with the top, and thus best mileage, in the 55-75 degrees F range.

Found a chart on Reddit of a Hyundai IONIQ Hybrid from 20-70 degrees F that indeed shows this cold weather decline. So if you combine that with what is shown in the video (I know it's apples to oranges with different vehicles, but the idea is sound), you would indeed get a bell shaped curve.

Did not put this together when purchasing the Hybrid, but it makes sense. It also makes sense about the CU result, because a pure gas engine always gets better mileage when the weather is warmer. So this tells me that in cold weather, the cold temperatures will hurt your MPG two ways, because of the battery for electric mode being less efficient and the gas engine running more due to a more inefficient battery or needing to warm the battery.

It's clear that Ford, along with other Hybrid makers, have some pretty sophisticated software constantly making decisions on what to do, based on multiple inputs from sensors. I now see why there is no way to put a Maverick Hybrid in purely electric or gas mode, controlled by the driver. They are saving us from ourselves, and thus from screwing things up. Our only controls are with the brake and throttle pedals, while watching the EV Coach display, and seeing what is reported as happening. I see this as just learning more about how our truck works.

I think.

In any case, we'll beat a Ranger or regular F-150 any day of the week in MPG.

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