Engine braking with the PowerBoost

[thudnblunder]

I'm new to the PowerBoost and I haven't driven in any mountains yet. With my other cars, to avoid riding the brakes on sustained descents I pick a lower gear for engine braking. With the PowerBoost, the behavior I see is that on shorter hills it switches to electric drive and uses the motor to recharge the battery.

What happens when the battery is fully charged? There won't be any more electrical load on the motor/generator so does the PB switch on the engine for engine braking or do the brakes end up doing all the work?

What's the best way to handle something like 4 miles of 5% grade downhill with the PowerBoost? Will locking out higher gears start the engine for engine braking?

Just trying to be better prepared before I head out to the Sierras.

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[Oxford_Powerboost]

I have a lot of experience with this given the mountainous area I live in. The ideal situation is you ride the brakes moderately (hopefully just in the “green” regen zone) until the battery is fully charged. Once that happens, the engine will come on and choose a low gear for engine braking so you don’t ride your service brakes. It’s not using fuel during this time. The power flow screen will display “engine on due to: engine braking”

locking out gears won’t engage the engine. You may choose to do so if the automatic engine braking isn’t enough once the engine cuts on. But in my experience it engine brakes pretty well

 

[SuperRaptor]

I'm new to the PowerBoost and I haven't driven in any mountains yet. With my other cars, to avoid riding the brakes on sustained descents I pick a lower gear for engine braking. With the PowerBoost, the behavior I see is that on shorter hills it switches to electric drive and uses the motor to recharge the battery.

What happens when the battery is fully charged? There won't be any more electrical load on the motor/generator so does the PB switch on the engine for engine braking or do the brakes end up doing all the work?

What's the best way to handle something like 4 miles of 5% grade downhill with the PowerBoost? Will locking out higher gears start the engine for engine braking?

Just trying to be better prepared before I head out to the Sierras.

If I just leave my PB in D without downshifting on a 5% grade (doing ~75 mph) it generally holds speed with the Eco Coach bar showing slightly over in the charging sector (green). If I downshift to 7th or 8th it charges faster but I start to lose speed.

If I press on the brakes and engage the regenerative braking it will shut the motor off even at 70mph and go into full E mode while charging.

I have had the motor start up when I've messed with downshifting to the equivalent of 3,500-3,800 rpm if the gas engine was on while in electric mode. It seems to me (anecdotal evidence) that the SOC of the battery and brake application % all come into play on how it reacts or keeps engine on/off.

Also @ 6% grades my truck builds speed from 70 mph, seems to be the break over point in my experiences.

 

[thudnblunder]

I have a lot of experience with this given the mountainous area I live in. The ideal situation is you ride the brakes moderately (hopefully just in the “green” regen zone) until the battery is fully charged. Once that happens, the engine will come on and choose a low gear for engine braking so you don’t ride your service brakes. It’s not using fuel during this time. The power flow screen will display “engine on due to: engine braking”

locking out gears won’t engage the engine. You may choose to do so if the automatic engine braking isn’t enough once the engine cuts on. But in my experience it engine brakes pretty well

Awesome, this is exactly what I wanted to understand.

 

[amschind]

One of the benefits of a hybrid is that the brakes last 1.5-2x as long as in a regular ICE vehicle. This depends upon driving habits, but one potential benefit is the ability to use more expensive pads and discs ecause you're not replacing them as often.

 

[Tosh]

Yesterday I took note of the "generator braking" in my Powerboost. Set cruise control for 60. Just as I reached the top of a hill, I dragged the brakes to shut of the ICE, but maintained 60. Re-engaged cruise control, truck stayed in electric mode all the way down the hill. At 61 mph I could feel significant drag in the drivetrain, and the EV coach indicator showed major charging to the battery. As I recall the grade on this hill is about 6%, and it's about 2 miles long.

I felt as though I was getting more braking efect from the electric motor/generator than I would from the engine alone.

 

[Snakebitten]

Fascinating stuff that I will not often experience in the flatlands. Amazing vehicle!

 

[Porpoise Hork]

Yesterday I took note of the "generator braking" in my Powerboost. Set cruise control for 60. Just as I reached the top of a hill, I dragged the brakes to shut of the ICE, but maintained 60. Re-engaged cruise control, truck stayed in electric mode all the way down the hill. At 61 mph I could feel significant drag in the drivetrain, and the EV coach indicator showed major charging to the battery. As I recall the grade on this hill is about 6%, and it's about 2 miles long.

I felt as though I was getting more braking efect from the electric motor/generator than I would from the engine alone.

I'll have to remember this trick the next time we head out to the hill country.

 

[SuperRaptor]

Fascinating stuff that I will not often experience in the flatlands. Amazing vehicle!

I do feel I get a lot of benefits of the PB when I'm going up and down hills. I swear I get better mileage with some downhill areas to help charge the battery, lol

 

[thudnblunder]

I might be in Yosemite in a week’s time. I’ll report back.

 

[Jimi]

Yesterday I took note of the "generator braking" in my Powerboost. Set cruise control for 60. Just as I reached the top of a hill, I dragged the brakes to shut of the ICE, but maintained 60. Re-engaged cruise control, truck stayed in electric mode all the way down the hill. At 61 mph I could feel significant drag in the drivetrain, and the EV coach indicator showed major charging to the battery. As I recall the grade on this hill is about 6%, and it's about 2 miles long.

I felt as though I was getting more braking efect from the electric motor/generator than I would from the engine alone.

Thanks for the info

 

[Thunderchief]

I live in the mountains of North Carolina and I use the Cruise Control to control speed going down the mountain roads. Always works for me.

 

[Oxford_Powerboost]

Sorry for the photo quality, my gf was trying to take the pic from the passenger side lol. But I was in a fully charged battery descending a mountain situation yesterday. This is what you’ll see - the engine popped on in a lower gear, and my EV coach is showing only a sliver of green and the rest is white real brakes. It stays in EV mode right until the regen bar gets to this length. One thing cool to note, if you have to tap the gas like the road temporarily evens out, it keeps the engine running for some time but only uses the electric motor, doesn’t inject fuel to the engine

 

[Calson]

It depends on the vehicle. With my GM 2500 truck using the manual transmission setting would disable grade control completely and not a smart thing to do. Wth my 2022 F-150 it came with the hill descent control feature that is activated with a push of a button on the dash and then the + and - buttons on the steering wheel. If the system overheats and shuts off then you are back to using the brakes.

The engine braking from its diesel engine was exceptional but with a gas engine the "braking" is nowhere near as effective and not something to rely upon.

Modern trucks have disc brakes at all four wheels and brake fade is not the problem it was with enclosed drum brakes.

Most drivers do not have a clue as to how to drive in the mountains and will brake too late and lock up the steering and then try to compensate. Ego driven drivers are the worst as they will drive faster than their limited skill can manage and have no knowledge of chassis loading going into a turn.

 

[JIMFOUNTAIN]

The engine braking from its diesel engine was exceptional but with a gas engine the "braking" is nowhere near as effective and not something to rely upon.

My hill descent experience has been a little different. I have found diesel engines to have terrible braking... unless they have a Jake brake or a compression brake or a Diesel Engine Exhaust Brake (Ford optionally equipment on super duty).

As far as gas engines and my experience the old saying applies "There is no replacement for displacement." Descent with my 3.5 L V6 vs a normally aspirated V8... the V8 wins hands down.

In fact I have been disappointed in how little help engine braking in my Powerboost is compared to the old V8 towing the same trailer/weight/route. Since it is a Powerboost I try to manage descents to max charge the battery but I often end up with the battery fully charged before I get all the way down. At that point the engine will spin to help out but I still end up using a lot more brake pedal than I did with the old V8.

Of course your mileage may vary

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