Driving in L (Low)

[Fat Fusion]

FYI guys (and new girl in So Cal :) ) I was in L when I had my system freak out and flash SERVICE ADVANCETRACK SOON.  The dealer ended up reflashing the transmission control module to fix it. 

[SD Diver]

Yikes!  FF - you are NOT having a lot of luck out of the gate.  Hopefully all of your initial bugs get squashed quickly.

 

FYI guys (and new girl in So Cal :) ) I was in L when I had my system freak out and flash SERVICE ADVANCETRACK SOON.  The dealer ended up reflashing the transmission control module to fix it. 

[tseibel76]

I drive in L almost all the time and have not had any problems so far. However, FF, after your post, now I'm hesitant to do that.

 

I don't think you get any better MPGe in L vs D, nor do I think you get more regen. I did an experiment one day. Drove a route in D and then the same one in L on the same afternoon (to account for temp, wind, elevation as much as possible). According to MFM, the results were almost identical (L was 1 MPGe higher) and regen was the same.

 

However, I like L because you don't have to anticipate lights as much as you do in D and it seems easier to get max regen without thinking so much about the breaks. Plus, if you have to stop unexpectedly, it's easier to get 100% regen if you are in L.

 

However, after your issue FF, I'm rethinking my L plans.

[Fat Fusion]

I wouldn't worry too much about it. It was only a software flash to fix it. If it does happen to you, turn the car off and on a couple times to get it drivable. Sounds like it was a rare condition since no one else seems to have experienced it.

[meyersnole]

I drive in L almost all the time and have not had any problems so far. However, FF, after your post, now I'm hesitant to do that.

 

I don't think you get any better MPGe in L vs D, nor do I think you get more regen. I did an experiment one day. Drove a route in D and then the same one in L on the same afternoon (to account for temp, wind, elevation as much as possible). According to MFM, the results were almost identical (L was 1 MPGe higher) and regen was the same.

 

However, I like L because you don't have to anticipate lights as much as you do in D and it seems easier to get max regen without thinking so much about the breaks. Plus, if you have to stop unexpectedly, it's easier to get 100% regen if you are in L.

 

However, after your issue FF, I'm rethinking my L plans.

 

I think the major difference here is how you drive. I have found that driving with the adaptive cruise (how did I live without this????) I have little need for driving in L, as the car takes care of all of the acceleration and regeneration on declines.

 

If you do not like to drive with the cruise, then I could see where driving in L can help. Just taking your foot off the accelerator and you are recapturing energy. However, if you are not careful with your speed regulation you could also waste energy -- sometimes L would be beneficial, other times you might be much better in N. When I took a trip in the mountains on my way to Pittsburgh I used L and even hill assist at times.  It is amazing how much energy this car can reclaim driving down a mountain  :shift: 

 

http://www.fordfusionenergiforum.com/uploads/gallery/album_8/gallery_42_8_39315.jpg

 

Like many others have mentioned I have used L at many different speeds and have never had any issues.  

[Fat Fusion]

I'm learning to LOVE the "L" LOL.  I am putting it in L exclusively now.  I really don't see any downside, while the upside is not having to use the "brakes" to charge nearly as much.  Plus you don't piss off the people behind you by getting on the "brakes" early.  I bet most people initially think my brake lights are out!

[Russael]

The only concern I have with L as it currently stands is that the brake lights DON'T come on.  From what I've heard, the Tesla S has had numerous rear-end collisions due to the regenerative brakes being so aggressive when you take your foot off of the accelerator, and the scary thing is the brake lights DO automatically illuminate on those cars.

 

I've followed a vehicle or two that had totally lost their brake lights, and when they begin to come to a stop, I don't immediately detect it, and had to brake more aggressively myself to keep from deleting their trunk. 

 

I have since learned how to feather the brake to keep from engaging the friction brakes.  Yeah, leadfoot Michiganders still fly around me, but eh, usually the light is green right when I get to it. :)

[Fat Fusion]

It doesn't sound like much risk to me, it doesn't slow that quickly IMO.  All of my manual transmission cars can slow quicker by downshifting than the Fusion can by regenerating.  I've actually had people tell me twice that my brake lights are out in my truck when I was just not using the brakes in stop and go traffic on the freeway.  My truck weighs about 6800 lbs and I've put new brake pads on twice in the front and once in the back over 300,000 miles!

[Dabu]

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 have this problem as I live on a large hill.  I have subsequently run into problems.  On two occasions, the "stop safely now" warning came on as I near the bottom of the hill.  On these two occasions, the ICE did not kick in, and I think either the battery or the transmission overheated.  I brought it into the dealer and they ran some diagnostics on the car but did not finding any codes.  Unfortunately, the service folks at the dealer are clueless about the new electric hybrid cars and did not offer much insight or give me any confidence in their assessment of what had occurred.

[Russael]

I'm not too convinced it's an overheating issue.  I'm leaning more toward something wrong with the regen system kicking over to ICE operation for your particular scenario.  A relay could be stuck or some sensor could be on the fritz.  With the ICE NOT engaging wouldn't have anything to do with heat... it's that particular component that is supposed to engage the ICE.

 

The car does have temperature sensors all over the place and it does spit up warnings for transmission temperature issues and I believe it'll kick up a warning if battery temperature gets out of control.

Edited December 14, 2013 at 10:56 PM by Russael

[larryh]

The only thing I could suggest is that you monitor the state of charge of the HVB using the MFT Electric Vehicle Information screen.    Is the HVB at 100% when you descend the hill, or does it go below 100% and then increase back to 100% as you descend?  At what state of charge does the stop safely now notification occur?  The ICE is used to brake the car when the SOC is at 100% to prevent overcharging the battery.  If the car fails to brake using the ICE, then a fail safe mechanism should kick in to prevent damage to the battery due to overcharging from regenerative braking.  Does the problem occur if you leave it in Drive and use the brakes?

 

If you fully charge the car and immediately afterward being descending down the hill, the ICE should start and brake the car soon after you begin the descent. 

 

The dealer should be attempting to reproduce the problem and/or get in touch with Ford to resolve the problem.  But it might be difficult if they are not near a hill to descend with the state of charge of the battery near 100%.

Edited December 14, 2013 at 11:40 PM by larryh

[larryh]

You could also reset a trip odometer before starting out.  Hopefully, the kWh of plug-in energy consumed does not go negative as you go down the hill, i.e. the regenerative braking is adding additional energy to the battery which is already full charged.   I don't know if it goes negative.   So maybe you could observe what it reads when you start out, without resetting it, and make sure that it never becomes less that what it was when you started. 

Edited December 15, 2013 at 12:22 AM by larryh

[Dabu]

I'm not too convinced it's an overheating issue.  I'm leaning more toward something wrong with the regen system kicking over to ICE operation for your particular scenario.  A relay could be stuck or some sensor could be on the fritz.  With the ICE NOT engaging wouldn't have anything to do with heat... it's that particular component that is supposed to engage the ICE.

 

The car does have temperature sensors all over the place and it does spit up warnings for transmission temperature issues and I believe it'll kick up a warning if battery temperature gets out of control.

Thanks again Russael, but I am not sure how to proceed next, as the dealer service folks seem to think the warning I had is due to user error (using L gear to go down a hill; I had to explain that I wanted to recupe some of the energy, with blank looks on the fellow's face), and more importantly, they couldn't find anything wrong based on their diagnostics.  They basically told me to stop shifting to L to go down hills....

 

The reason I was wondering if it had anything to do with switching to the ICE engine is because on my traded in Prius (2007), when the battery is full from going down the hill, the engine would "rev" to dissipate and avoid excessive charging of the battery.  It seems that this does happen occasionally with the Ford Fusion Energi, but not always.  With my Leaf, I also never had any issues going down the hill (but I do charge it to 80% for the most part, and have noticed that the regen does not occur if the battery is to 100% before heading down the hill.)  I really like this Ford, but these two incidents are making me a bit nervous.

[Dabu]

FYI guys (and new girl in So Cal :) ) I was in L when I had my system freak out and flash SERVICE ADVANCETRACK SOON.  The dealer ended up reflashing the transmission control module to fix it. 

Just curious, were you going down a hill with a relatively full HVB when this happened?

[Russael]

Fat Fusion also has a 2014 Fusion, so you may be having the exact same issue that he had.  You could always ask the dealer to update all of the software on the car with the latest versions...  We can update Sync ourselves, but when it comes to ECU updates, that's still only available to them.  There probably isn't any TSBs with that particular issue since the car is so rare, but, I'm sure they have new software versions for the transmission control module as well as many other items in the car.

[mmmhmmmm]

Both the Escape and the Fusion have continuously variable transmissions. There is no Low "gear"; The Low gear effect is the result of software trickery.

I prefer "L" because it's easy to avoid using the friction brakes. When I want the car to roll further I switch it to "D".

My ICE came on once while going steeply downhill in "L" and the EV display showed "Engine On Due to Low Gear". The battery was fully charged at the time so I take it the air compressor (ICE) was required to provide resistance, emulating the traditional "L" braking effect of a geared transmission. Usually when I come to a stop the battery needs charge so the L effect is provided through more aggressive regen. Gotta love technology!

Our other vehicle is an 2008 Escape Hybrid. We have driven the Escape in "L" for years. At 112,000 miles it is still has the original brake pads. I'm sure it's been done before, but I've NEVER put this many miles on brake pads. +1 for regenerative braking!

[Fat Fusion]

Just curious, were you going down a hill with a relatively full HVB when this happened?

No. I was going 2 mph after discharging about half the battery.

[Steve smith]

I thought I read on the Energi  data sheet it has a two speed CVT. Can anyone confirm or reject this ? I am going to set up the tachometer display to watch the RPM of the ICE when running both accelerating and decelerating.

[Kybuck]

A CVT is "continuously variable", which is essentially infinite "speeds" (or "gears")...

[Steve smith]

update.. A eCVT is unique. do a search for eCVT .  It is a power split device transmission that uses one single planetary differential gearset.  NO BELTS used.

[meyersnole]

update.. A eCVT is unique. do a search for eCVT .  It is a power split device transmission that uses one single planetary differential gearset.  NO BELTS used.

 

Thanks Steve! I did not know that. Very cool, I like this better as I was wondering how durable the belt driven would be verses the gears.

[Markn455]

California has an area on Interstate 5 from LA north to the valley known as the "Grapevine". The descent drops about 2300 feet in 6 to 7 miles. Just using hill assist, it kept my Fusion Energi at 60mph and put 5 miles back into the battery. I did try a shift to low but it slowed me too much so I shifted back to drive within 15 seconds. At no time did the engine engage and my milage reading came up to 54.1 mpg. Gotta love this car!!!! Even if I never reach the goal of 100MPGe I'll take 50 any day.

I have learned through trial and error that hill assist does re-generate more aggressively. Another thing I noted using the feature In the East Tennessee mountains it did a great job of maintaining speed and regeneration to a point. If the hill assist can't maintain speed, I noticed it actually starts using the HVB to place additional resistance by applying power to the electric motor to increase drag. I proved this by observing the KV power in the empower screen also the percent charged i could see the charge level start going down. Slowing the car slightly with the brakes and the system went back to regenerating the battery.

[Rexracer]

I have learned through trial and error that hill assist does re-generate more aggressively. Another thing I noted using the feature In the East Tennessee mountains it did a great job of maintaining speed and regeneration to a point. If the hill assist can't maintain speed, I noticed it actually starts using the HVB to place additional resistance by applying power to the electric motor to increase drag. I proved this by observing the KV power in the empower screen also the percent charged i could see the charge level start going down. Slowing the car slightly with the brakes and the system went back to regenerating the battery.

 

Thanks for the update. This makes sense, aggressive regen, but turning into power consumed to achieve the same results as engine braking.