Fuel Economy: What is just as important as EV?

[Riddley]

For those wanting to get 5 MPG better fuel performance, here is a technique that made this much difference in my driving.

 

I started to pay attention to the battery icon. Prior to this discovery, my total focus was on the EV mode. How to get into EV mode as often as possible, and for as long as possible. While important, the total focus on EV mode alone proved to have limited results.

 

About the battery icon: I set the display for this to show when the battery is charging and discharging. This display mode simply puts an up arrow (or chevron) above the battery when it is charging, and a down arrow (or chevron) below the battery when it is discharging. This should not be new information for most people, but it might help some... :)   <see the chevron above the battery in the image below - borrowed from JUS - thanks JUS!!> :rockon:

 

Why this is important:

 

Driving in EV mode as much as you need to for optimal fuel economy requires a well charged battery. If you don't pay attention to that battery icon, you will not have it sufficiently charged to provide optimal EV driving.

 

But the battery icon tells you something else that is just as important, if not more important: it tells you if your foot is too heavy on the gas pedal. The implication being that a heavy foot will result in more fuel used per mile. This is subtle, but very important to improving fuel economy. Often times I am driving on a flat road, not in EV mode, and I look down at the battery gauge and see the down arrow (chevron) under the battery icon. It is discharging. I lift just a touch off the gas, almost imperceptibly, and the chevron goes to the top of the battery - it is now charging. That small change in pressure on the gas pedal was so slight that there was almost no change in my vehicle speed. It might be like a 1 MPH change, very slight. One time the light foot lift off the gas didn't result in the up chevron (charging) and I looked around and noticed that my AC was set too high. I clicked the AC fan down one or two clicks and the battery started charging again. Subtle change. But important.

 

I've come to the conclusion that the battery display, whether it is charging or discharging, is fundamental to improved fuel economy. If you don't monitor it at all, you will struggle with getting optimal economy. The up chevron above the battery is your FE friend, the down chevron below the battery eats your fuel economy. 

 

 

It is not always possible or desirable to have the battery in charging mode. Sometimes the battery will be discharging under normal operation, like when you need to accelerate, or if you are in EV mode. But giving just a little bit if your attention to the whether battery is charging or discharging, and working to get the battery into the top third (of being fully charged), will make a difference in your vehicle range and FE.

 

In the spirit of JUS and his naming conventions for FE techniques (ICE High, P&G, etc.) I suggest this strategy might be labeled "Feed the Battery". Whenever possible - Feed the Battery.   

Edited May 20, 2013 by Riddley

[Edsel]

Going to try this out.

[Jus-A-CMax]

Good stuff Riddley - feel free to borrow any pics as you or others need :)

[Recumpence]

I would say the advanced version of this is to know your route well so you can plan when to run in EV mode and when to drive to maximize charging. This becomes second nature after a while.

 

Matt

[Riddley]

Very good point Recompence! 

 

Having the same daily commute has me sometimes feeling like a mouse that's been running in the same maze for a long time. One silver lining is knowing when I will get a recharge of the battery, and when it's OK to run it down under EV anticipating the next hill.    

[Recumpence]

I do this a HUGE amount during every day's driving routine. I kow when I have a long stretch of flat road that can maximize EV and when the engine is going to run anyway (maybe for along up hill climb) and I plan my driving accordingly. "Oh, this hill is coming up, I can EV until the hill and let the battery charge as I climb (because the engine is more efficient at higher power output than just climbing alone and I can use that added efficiency to charge the pack)". ---or--- "Hey, I have a long down hill stopping situation approaching. That will charge my pack, I can run it down in EV before then."

 

Matt

[JAZ]

Matt, I'm thinking that with your tire psi @ 51, you must have some pretty decent roads where you are.  Here in Michigan with the spring thaw(s) and resultant potholes--aka bathtubs--- I'd be fearful of running those pressures.

[Recumpence]

Actually, higher pressures reduce the chances of a pinch flat.

 

The car does ride a bit more harsh with more pressure, though.

 

Matt

[fotomoto]

I would say the advanced version of this is to know your route well so you can plan when to run in EV mode and when to drive to maximize charging. This becomes second nature after a while.

 

^  This.

 

On my daily route, I have a couple of straights that vary in length from 1-3 miles at 55-70mph.  I had been trying to get a max batt before these straights in hopes of getting the high ICE mode to kick in but after several tanks with OK results I decided to try the above.  Now with some forethought, I can drain the batts in EV and use the periods when I need to either accelerate, going up grades, or cruise hwy speeds to recharge.  I've seen as high a 5mpg increase on each commute leg and currently netting a +3 on the overall tank even though I have more overall hwy miles on it due to a couple of out of town trips.  I think these daily straights are just too short for any meaningful high ICE results.  

 

As always, YMMV.