Western Mountain driving, braking and battery regeneration

[jgcec@yahoo.com]

I was driving down from the Lake Tahoe area which is about 7,000 ft down to sea level and I thought that if I maintained a lightly applied brake force it would regenerate the battery faster. I did add about 11 miles to a completely drained battery.

 

After applying the brakes for about a minute, I noticed the brake burning smell.

I don't know if it was coming from my Energi or the truck in front of me.

After that I only pumped, (meaning keeping the brakes on for 10 seconds or so, then release) the brakes or not used the brakes at all and just let the engine slow the car down maintaining about 55-60mph. It still added another 5-6 miles to the battery from about 5 miles at that point. I did not notice the smell again, although I was not consistently behind a truck either.

 

How long can the brakes be applied before damage is done to them?

I have read that it would be better just to use the Low gear option, than using the brakes in mountain driving.

 

Any comments, suggestions?

[FusionDad]

If the grade is steep enough and continuous enough, your car will self-charge the battery by itself, without using the brakes.  On a loooong father-son cross-country trip this August, we did this twice in the West: once crossing the Bighorn Mountains in Wyoming from East (from the Black Hiills) to West (to Cody) and gained 20+ free EV miles because the road, once over the pass, descended continuously and gently down a beautiful canyon wall for some 30+ miles, with little if any brake use.  The other time, we self-charged 43 "indicated" EV miles descending from Pike's Peak in Colorado (and yes we did use brakes on that road 'cause you just have to use them all the time on that descent).  

 

Two notes:

 

1). the park ranger at the brake temperature checkpoint commented "cool brakes, very good job guys".  This I attribute to the regen function of the hybrid axles, since the axles in regen mode can slow the car much more than do axles in a regular car.  

 

2).  the "indicated" 43 EV miles of course turned out to be a tricked computer algorithm, and got used up within 23 miles as soon as we hit the flats in Colorado Springs.

 

So my suggestion, after driving our Prius Plug-In for 32+ thousand miles and the Fusion Energi for close to 15 thousand miles, is to "just drive it" and not try to gain free energy by specifically burning up your brake system.  If the mountain is big enough, you'll get free EV miles no matter what.  And if it ain't big enough for that, then in the long run it's not worth using up the brake components, i.e. you can't get something for nuthin'. 

[Eric4539]

Depending how well traffic is moving you can use Grade Assist (the button of the left side of the gear shift lever) which maintains a constant speed as you are descending a hill.  That feature allows the car to decide if it needs to use the engine to propel the vehicle or to charge the battery while maintaining the speed you set as you descend.  Not sure if L or Grade Assist works better.  I like to use L for the rare occasion when I am in bumper to bumper traffic.

[meyersnole]

Just to further what FusionDad and Eric4539 said, I also took a trip through the mountains back in September. I used cruise control and grade assist to recapture battery (also going from an empty battery to miles on the gauge).  When the decline is steep enough you will get the swirl over the battery without touching the brakes. 

[FusionDad]

Ya know - we both completely forgot about Grade Assist during our 7,000 mile trip...  this car has so many buttons it's hard to remember it all   LOL :whistling:

[Fat Fusion]

Depending how well traffic is moving you can use Grade Assist (the button of the left side of the gear shift lever) which maintains a constant speed as you are descending a hill.  That feature allows the car to decide if it needs to use the engine to propel the vehicle or to charge the battery while maintaining the speed you set as you descend.  Not sure if L or Grade Assist works better.  I like to use L for the rare occasion when I am in bumper to bumper traffic.

 

 

There's a significantly steep hill between my house and where my folks live.  In Hill Descent the car will go from 20 to about 28 on the way down the hill.  In L the car will stay at 20.  I drive exclusively in L now, regardless of where I drive.

[Steve smith]

The smell from regen braking can also be the HVB taking a charge. I have a very faint hydrogen gas smell (the cooling fan discharge air goes into the cabin) when I regen from coasting down a hill or lightly braking which actually does not apply much pressure to the brakes themselves.

[murphy]

The smell from regen braking can also be the HVB taking a charge. I have a very faint hydrogen gas smell (the cooling fan discharge air goes into the cabin) when I regen from coasting down a hill or lightly braking which actually does not apply much pressure to the brakes themselves.

Hydrogen is odorless.

Properly operating Lithium-ion batteries are a sealed unit.  They don't expel anything other than heat.

 

Regen done lightly does not engage the service brakes at all.

 

Check that the vent tube is still connected to the top left rear corner of your 12 volt battery.  It vents gas underneath the car.  Also check that the white plastic plug is installed in the vent hole at the front of the 12 volt battery.

[Steve smith]

My 2014 Fusion Energi only has 900 miles on it and what I faintly smell might be the battery case the cooling fan is blowing some heat off of. The front 12v vent is plugged fine and the rear vent tube is in place like it should be. The smell is similar to new electronics smell that goes away after a little use. The wife cant detect any odor other than that great new car smell.