Driving in L (Low)

[Depauwler]

Why not just leave it in L?

[dlb92]

Driving in L all the time is less efficient especially if you aren't using some kind of cruise control.

[Depauwler]

How so?  It's not a different gear set.  It's just more aggressive regen braking; shouldn't have any effect except on coasting.  It's not actually "Low" gear.

 

I'm tempted to try it myself, a week on D, a week on L, but the driving style is different, I'm worried I'd be expecting L's braking and misjudge my use of the brake pedal.

 

Ahh, hmm.  From the manual:

 

Low Gear:

Low gear (position L) is

designed to mimic the enhanced engine

braking available in non-hybrid vehicles.

Low gear will produce high engine speeds

to provide necessary engine braking. This

is normal and will not damage your vehicle.

In low gear, the gas engine will remain on

more often than in position D.

 

I would take this to mean I'm right.  It's only mimicking  the engine braking.  Nothing else should be affected.

However, I hadn't noticed that part about the gas engine remaining on more often than in D.  I don't really understand that, unless it's talking about having to turn the engine on to provide braking if regen can't handle it.  And it says it will produce high engine speeds.  It does sound as if you shouldn't use this while using the ICE.

At any rate, I've been driving in L exclusively (except after a full charge) for a month now and the engine hasn't come on once (not including the use of EV Later).  But I'll take it under advisement; next time I go into hybrid mode, I'll switch back to D.  Probably not a bad idea for other reasons as well, I worry that at those speeds I'd put too much faith in L's engine braking and be too slow to use the pedal.

 

I still don't see the point of shifting into and out of L for stop signs and stop lights, unless you are in hybrid mode.  But to each their own; I typically only drive short distances around town at < 45mph.  Probably could have gone for a straight EV, but once in a while I'll take a long trip at > 60 mph (which is the only time I go into hybrid), and according to the plug-in maps I've looked at, there's not a single one between me and my destination.

[larryh]

You recover about 75% of the kinetic energy from regen when slowing down.  Unless you intentionally want to slow down, regen wastes energy.   When using L, you are not able to coast due to the aggressive regen.  To maximize efficiency when using L, only let off on the gas pedal when you intentially want to slow down for a stop sign or something.  Otherwise, you should keep the foot on the pedal and try to minimize regen.  If you driving in D, you don't have to be as careful with trying to prevent unintentional regen since it is much less aggressive and coasting is possible.

Edited August 17, 2013 at 02:30 PM by larryh

[Depauwler]

Good points, but I find that's what I'm already doing.  Unless I really want to slow down I always keep a little pressure on the pedal.  The battery indicates it's receiving a charge but I don't slow down as if I'd completely left off.  Maybe that's no better than riding the brake pedal in D, but oh well.  I just don't see the point in shifting.  It's just another thing to worry about, another distraction, another repetitive motion bound to wear something out all the quicker.  Still tempted to give the different things a try and see how it comes out, but my drives are short and at low speed, so I don't know how much use it'd be; I don't really coast on the trip to and from work.

 

But to use it the way described, I'd rather it be the grade-assist button.  Just press the button for more regen (regardless of grade) and it'd be the equivalent of L except for automatically disengaging when you picked up speed again or pressed the button again.  I don't want to feel like I bought a stick shift!

Edited August 17, 2013 at 06:47 PM by Depauwler

[Depauwler]

Well, hmm.  Went out tonight, drove in L there.  Drove in D back.  I know one trip doesn't mean much, but tried to make it as fair as possible, and according to the Trip Summary, D won.  157.5 to 188.8.  Guess I'll try shifting to L at stops next week.

 

Edited August 18, 2013 at 03:46 PM by Depauwler

[FusionEnergi]

I have tried shifting to L on two occasions. Both times as soon as I let off the gas pedal, the ICE came on . Both times I started slow and once I was up to 5 to 10 mph I let off the pedal. The engine came on and I quickly stopped. Turned the car off and shifted to D. Then continued my EV journey home. Am i doing something wrong? I am using EV now.

I saw the message Engine on due to ? Didnt finish reading it I went into EV panick mode.

Edited August 19, 2013 at 08:28 PM by FusionEnergi

[larryh]

If the HVB is fully charged, the car cannot use regen to slow the car.  It has to use the ICE instead.  Wait until the HVB is discharged a few percent before using L.

Edited August 19, 2013 at 08:36 PM by larryh

[FusionEnergi]

Thank you, I will try that. You are correct I had just fully charged the battery at work and was heading home.

Edited August 19, 2013 at 09:09 PM by FusionEnergi

[FusionDad]

We had our Fusion Titanium since Memorial Day weekend.  We (Son and I) are currently on a 3-week cross-country trip.  Several days ago, we drove the Fusion up Pikes Peak in Colorado from Colorado Springs, an altitude change of almost 8 thousand feet (from 6500 to 14,100+). The dedicated Pikes Peak road is just over 18 miles long.  Of course, after attaining the top we drove the car back down.

 

Up: I was driving. Just about the treeline, which is more than halfway up, we pulled over and we both smelled the underbody - it was pretty warm, warm enough to faintly smell.  At that point, I switched from D to L.  The smell vanished and the car felt better on the remaining very high inclines up to the summit.

 

BTW - per my old aeronautics textbooks a combustion engine loses 3% power for every 1000 feet of altitude - so @ 14,000+ feet, the car was at around 60% power or less.  You could feel it. 

 

On the way down, my Son drove.  The hairpin turns being pretty hairy above the treeline, I insisted he stay in L.  Just inside the treeline, with around 13 miles+ to go, there's a ranger road check station where the ranger laser-checks every descending car's front brakes' disc temperature.  He checked ours, nodded approvingly and said "that's pretty cool - keep doing what you're doing all the way down".  Thank you regen braking  ;-) 

 

The EV traction battery had of course been regenerating since the summit, where it had been empty.  It showed 43 "EV miles" around three miles before the end of the descent.  At that point, it quit taking any more charge to store, although the regen spinner kept spinning - i.e. the regen charging kept producing juice, but the battery was full and closed itself for any more.

 

Our other car is a 2012 Toyota Prius Plug-In we've had for fifteen months, and based on that car's behavior I fully expected the Fusion's internal combustion engine to come on to shed the excess electricity.  Well, it didn't.  Not to the end of the Pikes Peak road (3 miles), and not during the almost all downhill drive to Colorado Springs - another 10+ mile descent.  Maybe there's a Zener diode somewhere in the Fusion to convert excess electricity into heat?

 

We immediately went to Denver for the afternoon, about 65 miles away.  Son and I were betting whether the "43 EV miles" would really turn into actual 40+ road miles.  Unfortunately, the EV charge was all gone at Mile 23, with the car at standard freeway speeds the whole way.  

 

IMHO, the only way to explain the unusually high EV miles display is that the unusually steep and long descent somehow spoofed the Fusion's algorithms.

[FusionDad]

... and yes, the car is well broken-in now after Pikes Peak   :rockon: 

[larryh]

Are you sure the ICE did not come on?  I believe it comes on, but it does not use any fuel when used for braking.

Edited August 23, 2013 at 08:56 PM by larryh

[FusionDad]

I and Son are both certain - we were watching the displays like hawks.  The grayed-out ICE icon stayed grayed out.  This is the dash left-side display, which we have set up to show the combined blue EV use band, the white ICE use band and the blue EV charging band.

Edited August 23, 2013 at 09:03 PM by FusionDad

[Rhyalus]

If you watch the amount of battery energy used while driving in L, it is obvious that it uses more energy than D. You may get more regen, but the cost is not worth it.

 

There may be some dependency on the road grades, but for flat road driving, L is a bad choice.

 

R

[Depauwler]

Yes, I believe it now that I've switched back to D; I think I can see a difference in my commute MPGe.  Almost got 300 MPGe one day.  I don't believe it uses more while driving, but in D, you have more and finer control over the regen.  Ah well, I was getting worried that L was going to get me into trouble (foot not on the brake if sudden braking needed) anyway.

[Rhyalus]

Yes, I believe it now that I've switched back to D; I think I can see a difference in my commute MPGe.  Almost got 300 MPGe one day.  I don't believe it uses more while driving, but in D, you have more and finer control over the regen.  Ah well, I was getting worried that L was going to get me into trouble (foot not on the brake if sudden braking needed) anyway.

Drive the car in Empower mode and just look at the amount of power. I think you can see the difference between L and D very clearly... At least in my car....

 

R

[Energized]

Drive the car in Empower mode and just look at the amount of power. I think you can see the difference between L and D very clearly... At least in my car....

 

R

 

When I move between D and L  I do not see any difference.

[tseibel76]

Hi Everyone!  I just got my Fusion NRG on Monday (10/14).  I have been experimenting with D and L.  It seems to me my MPGe is about the same with both.  However, it seems I get more range in L mode.  Nothing scientific yet, just experimenting, but it seems L puts more power back in the pack.  I'm lucky in that I drive about 18 miles total everyday, so I have yet to use the ICE (except when I drove home from the dealer in Fargo (only place in ND that sells the NRG), which is about 185 miles away).  So far, I love the car.  Amazing technology!

[Russael]

Welcome to the boards and welcome to your new Fusion Energi. :)  An 18 mile commute is just about perfect to stay in EV mode for your entire trip.  Ask questions if you can't figure something out or can't find it on the boards.  We all try to help each other out as much as we can.

[tseibel76]

Will do.  Thanks Russael.  I ran errands around town yesterday and used L.  All city driving, mixed hills and flat stretches.  I went 15.7 miles, all in EV, in 4 "trips".  No CC and it was about 44 degrees.  When I got home, I still had almost 1/2 my battery left.  In one stretch, I went down a hill and put about 3 miles back in the pack (according to the estimate on the gauge).  According to MFM, when I plugged in yesterday afternoon, it took 3 hours and 4 minutes to charge the battery to full.  I plan on doing my normal weekday commute in both D and L and see if I notice any difference.  I'll post the results.

[tseibel76]

Forgot to attach the screen shot from MFM of the day.  

 

[Doctor Emmett Brown]

It would be interesting for one of you to try going down a grade in L or hill assist with a full battery.  I'm pretty sure that is when the ICE will kick back on to aid in slowing the vehicle through compression.  Once a battery is full, it can't take any more charge so either the electricity has to be dissipated in a resistor (like diesel-electric locomotives) or something else has to take over like the ICE.

I just got my car today, and I'm not quite sure I understand exactly what's going on here, but I have the opportunity to test this out.  The name of my street is Pinnacle, so as you might guess the first mile of my commute is downhill at a pretty good grade.  I believe the elevation drops 400 ft in a mile.  (i know bc I run down it, and unfortunately back up).  I will drive down it with a full battery tomorrow will hill assist on.  Monday I will try it in low gear.  what exactly is it that you want me to look out for tho? MPGe?

[murphy]

If the HVB is full neither hill assist or low gear would be able to provide any braking since there is no place for the energy that is generated to go.  The engine should come on to provide the back pressure while descending the hill.  There should be no fuel consumed by the engine.  Either clear one of the trip meters or note the fuel value before you start out.

[Doctor Emmett Brown]

If the HVB is full neither hill assist or low gear would be able to provide any braking since there is no place for the energy that is generated to go. The engine should come on to provide the back pressure while descending the hill. There should be no fuel consumed by the engine. Either clear one of the trip meters or note the fuel value before you start out.

[Doctor Emmett Brown]

That's exactly what happened