downhill driving button turned on

[mtb9153]

I have found that driving with the downhill button pushed on allows me better AvMPG numbers. While driving on fairly level city streets at 35-40mph within a city block I saw my numbers increase from 43 to over 50. My question is does it hurt anything by driving with it turned on for longer periods after the road levels out. There just seems to be more increases in my tenth of a mile digit over when it is turned off. With it off if my numbers drop down to 40 and I push the button, right away the .X number starts increasing steadily. Has anyone noticed this?

Edited March 14, 2014 by mtb9153

[Tdefny]

Thanks. I havent played much with downhill assist except on the rare hills around here and it seems to help there.

[bemyax]

After I started using the OBDLink device I discovered the CMax has accelerometers built into it like a smart phone, or tablet computer. It's how they know to reorient your display when you tip the device. I've tried tapping the Grade Assist on when coasting up to a red light hoping for just a little extra regeneration without touching the deceleration pedal. Nothing, however. Works great in a nearby town with many steep hills. My hunch is that when we activate the circuitry, any extra regen or motor braking must clear two hurdles. 1) Tilt. If the car isn't far enough out of level, nothing happens. 2) Acceleration. If the car isn't picking up speed, nothing happens. Now that I think about it, I should be able to see it by watching the HV amps while coasting down and tapping the button on and off. Will try it on today's drive.

[bemyax]

Okay, bear with me. I've never uploaded a video, or shared a link to it. In these different charging situations, I couldn't see a difference. https://plus.google.com/103508686568546342692/posts/4twuk7vL5N9 I realize the units are probably off because of an error in the formula; this is simply to look for a  change in current flow.

[mtb9153]

Hey I like that, what app is that you have running?  What is the device also?  Curious if I can do this using my iPad mini?  Nice job with the video.

[bemyax]

I've been running the OBDLink MX Bluetooth adapter. The app is Torque Pro running on a Nexus 7(2013) tablet. The video was shot with a Samsung Nexus smartphone mounted in a Scosche power outlet type from WalMart. I learned the hard way - always quit the Torque Pro app before turning off the car. I got in a hurry a couple of nights ago, forgot, and upon restarting CMax, the electronic control unit (ECU) crashed. Ouch. I think the ECU can't boot while the adapter is doing rapid polling.

 

I suspect an Apple application is more of a rare bird. It has something to do with communications needing to work in a way that iOs won't approve.

 

The video load and presentation was actually the path of least resistance. The way all of the Google functions are hooked together, posting stuff like this is something one needs to resist, rather than work at. In order to remove variables, I picked a long, level stretch of highway nearby using Eco Cruise. The only variables I introduced were how I loaded our machine (speeds) so we could see each combination of charge/discharge factors. The one I missed was where we know grade assist works. I don't have a long steady grade to work with.

[ScubaDadMiami]

My hunch is that when we activate the circuitry, any extra regen or motor braking must clear two hurdles. 1) Tilt. If the car isn't far enough out of level, nothing happens. 2) Acceleration. If the car isn't picking up speed, nothing happens.

That's what I've found. When I was in the mountains, it worked great. When going down modest slopes, nothing happened. It's been a while, but that's how I remember it. This is why, from what I recall, there is no harm in leaving it activated. I guess that they added the feature so that you can turn it off to increase speed while going downhill on a glide, for occasions where this is what you want to be able to do so.

Edited March 16, 2014 by ScubaDadMiami

[shinytop]

Where is the obdlink connector?  I just ordered one and have downloaded the torque up.  Will get the link on Tuesday.

[MichaelM]

I have found that driving with the downhill button pushed on allows me better AvMPG numbers. While driving on fairly level city streets at 35-40mph within a city block I saw my numbers increase from 43 to over 50. My question is does it hurt anything by driving with it turned on for longer periods after the road levels out. There just seems to be more increases in my tenth of a mile digit over when it is turned off. With it off if my numbers drop down to 40 and I push the button, right away the .X number starts increasing steadily. Has anyone noticed this?

 

Brother Mike, I have noticed the same thing on my SEL. It wasn't a huge increase but I went (since the temp increased) from 43-47MPG for the 60 mile trip in to work each day to regularly seeing 47-50. The trip is mostly rolling hills with stretches of slight up or down grades, nothing that should trip any of the accelerometers. But, with that being said I noticed the numbers increase along with a much closer fuel used number than before, says (11.7 GAL used, pumped in 11.37) Not sure why, but I'm leaving it on until somebody tells me it will hurt my car

[Jus-A-CMax]

Intriguing. I don't even use this feature on the steep & long downgrades - hate the noise and imo, having the ICE mpg 60+ seems less than the blue EV mpg 60+ .I am doing a gym run today and I usually score 94 to 105 so lets see if this down grade assist button on will make any difference. Good eyes Brother Mike....oh by the way, go check out the Bar thread - I left a special post for you Bro ;)

[HotPotato]

The only downside I've noticed to having it on is a jerky disengagement when coming to a stop at the bottom of a hill. Like the others, I don't notice that it does anything in the absence of a hill...suggesting it's not a switch to turn up the regen percentage (which would be kinda cool) but rather exactly what it's presented as: a way to hold a constant speed when going down a hill, through whatever combination of regen and engine braking will do the trick (which is ALSO kinda cool -- yesterday I was driving through some crazy mountain passes and backroads, and as heavy as the C-Max is, it's nice not to have to worry about brake fade or speeding tickets).

[ScubaDadMiami]

I used DHA a lot in North Carolina. Looking forward to using it some more in New Hampshire and Vermont. For me, it does not engage (small "E") on flat terrain.

[Adrian_L]

The only downside I've noticed to having it on is a jerky disengagement when coming to a stop at the bottom of a hill. Like the others, I don't notice that it does anything in the absence of a hill...suggesting it's not a switch to turn up the regen percentage (which would be kinda cool) but rather exactly what it's presented as: a way to hold a constant speed when going down a hill, through whatever combination of regen and engine braking will do the trick (which is ALSO kinda cool -- yesterday I was driving through some crazy mountain passes and backroads, and as heavy as the C-Max is, it's nice not to have to worry about brake fade or speeding tickets).

 

So the "jerky disegagement" is normal!?.  I thought there was a twig caught in the gears when it happened last week! 

Edited June 9, 2014 by Adrian_L

[Jus-A-CMax]

Nothing special to report. Spent yesterday driving from home to golf course, to gym and back to golf course and pulled the car in, 63MPG. Driving to work today, I was actually low at 77MPG and then golf course, gym and home and finished the day at 62MPG. All city. Infact, if anythng, the DHA slowed me down momentum wise when I was going downhill like it was suppose to do.

 

I think what Brother Mike might be experiencing is the DHA boosting his SOC instead of him riding the regen (assuming he even does this). Higher SOC = more EV. But for those who use the momentum, its counter productive. Jus my 2c....damn, running out of pennies here... :skateboard:

 

No noticeable "jerkiness" either at stop. I try not to stop but when I have to....

Edited June 10, 2014 by Jus-A-CMax

[SnowStorm]

Hey, I didn't even know that button was there (or forgot) - haven't tried it yet but certainly will.  I have tried L on the shift lever but that seems problematic.  Way too much "braking", ICE racing at 4 to 5,000 rpm, and then the ICE won't shut off unless you stop and shift to park!  Is that normal???  Made no sense to me, shifted to Neutral, then sopped, ICE kept running.  The button sounds way better.