Coasting Downhill Maximum Recharge

[RickLightning]

Did you add more kWh than what you would have used accelerating? Any time I can make a car go faster without pushing on the accelerator (I.e. spending kWh) that’s kinda like adding kWh to the bank.

Let’s say the speed limit is 60. Assuming you don’t impede traffic, if you slow to 50 up the hill, then shift to neutral and speed up to 60 down the hill, is your state of charge higher or lower than if you held it at 60 up the hill and regenerated something down the hill? I think that would require some testing before being dismissed out of hand.

Shifting to N gives no regen. And no control. I was taking A curves as fast as I would normally drive, and it regenerated the whole way.

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[KurtsRPMGarage]

60-70% of what? If kWh regenerated is the numerator, what is the denominator?

It’s 60-70% of the kinetic energy contained in a mass traveling at a certain velocity. It’s typically expressed in joules but can be converted to watts. So 30-40% is lost to heat. Standard brakes convert 100% to heat. This is why it’s technically still more efficient to get up to speed and coast to a stop rather than maintain speed for longer and use the regen to stop you. Friction will always be there.

 

[MM in SouthTX]

It’s 60-70% of the kinetic energy contained in a mass traveling at a certain velocity. It’s typically expressed in joules but can be converted to watts. So 30-40% is lost to heat. Standard brakes convert 100% to heat. This is why it’s technically still more efficient to get up to speed and coast to a stop rather than maintain speed for longer and use the regen to stop you. Friction will always be there.

Ahhh…
I’ve been wondering what that equation is. Thanks. People talk like they are getting back 60-70% of what they put in. That can’t be the case because if you are slowing down from 60 mph, we don’t know how much was put in to get to and maintain that speed.

I have been guessing that if the brake coach says 100% it means that all braking was done by regen, and if it says 90% then 10% was done by the regular brakes. Is that correct?

Would love to see the uphill/downhill experiment in various modes.

 

[Ekiehn]

I went from about 1/2 mile high all the way to the bottom and scored about 18.3 kwh... use single peddle to max out regen..

Hey Lightning Owners,
Does anyone have good experience with "coasting" out of the mountains to maximize recharge? I'm about to go on my first camping trip with my new Lighting (extended range battery), and I legitimately have range anxiety. I'm obviously going to burn most of my range on the way up the canyon into the mountains but am hoping to regenerate a lot of charge on my way down to make it home or to a charger. I'm just not certain what drive mode I should be in to maximize the recharge on the way down. I typically drive in 1-pedal, but this would obviously bring me to a stop, so not planning on using that one. Anyone have experience with coasting out of the mountains using Sport, Tow, or Regular drive modes? I'll probably have around 1,000 lbs worth of gear in the bed, and I won't be towing a camper or anything.

Thanks!

 

[RickLightning]

1 Pedal...

 

[trichard83]

I went from about 1/2 mile high all the way to the bottom and scored about 18.3 kwh... use single peddle to max out regen..

Thanks. I know there are a ton of factors involved with this, slope of the mountain, weight of truck, and finding that right balance where my speed is offset by the friction regeneration. With my last truck, I would downshift and let the engine slow me down so I wasn't burning my brakes, so I'm hoping one of the drive modes will do this for me. Appreciate your comment!

 

[RickLightning]

Thanks. I know there are a ton of factors involved with this, slope of the mountain, weight of truck, and finding that right balance where my speed is offset by the friction regeneration. With my last truck, I would downshift and let the engine slow me down so I wasn't burning my brakes, so I'm hoping one of the drive modes will do this for me. Appreciate your comment!

Tow/Haul may be of interest, or Sport mode.

 

[Skidrowe]

It sounds like you want to put it in a mode that would be like riding a lower gear down the mountain so that engine braking helps you maintain speed.

With 1PD, it will assume that you intend to stop if you take your foot entirely off the gas. That's not what you're looking for. To get what you want with 1PD, you'll have to find that sweet spot on the pedal that maintains the speed you want down the hill. That spot would theoretically use regen to slow you when needed or use power to speed you up.

With 2PD, you'd coast when off the gas pedal and if you go too fast then depressing the brake will engage the motor to slow you down with regen. If you don't brake too hard, then it will be all regen and no friction brakes.

Cruise control is the closest thing to what you're looking for and it will engage regen and if necessary, the friction brakes to maintain a speed. It might not do it as efficiently as you. Or if you wait until the last minute to make sudden changes in speed, it could possibly be more efficient. I find that cruise tends to accelerate more aggressively than I do and brake harder at the last second than I do. So for me, it would be less efficient in your downhill scenario.

Sport mode has more aggressive motor regen settings, but that might not translate to more power recaptured because there will be scenarios where you simply want to slow a little where less regen is needed. Try it and if the regen setting for it when off the gas pedal matches the grade of the road, it might be like selecting the perfect gear in an ICE to maintain speed down the hill.

I'd recommend you use 1PD or 2PD (based on comfort level) with normal mode and either modulate your speed through throttle control in 1PD or through coasting and brake control in 2PD. Both of them will use regen braking first and won't engage the mechanical brakes until you attempt to slow at a greater rate than the regen braking can handle. This gives you the control to ensure that you coast and use regen braking as much as possible to maximize your range while traveling down the mountain.

 

[TheWoo]

Thanks. I know there are a ton of factors involved with this, slope of the mountain, weight of truck, and finding that right balance where my speed is offset by the friction regeneration. With my last truck, I would downshift and let the engine slow me down so I wasn't burning my brakes, so I'm hoping one of the drive modes will do this for me. Appreciate your comment!

Cruise control is the best substitute for engine breaking. It will use regen to slow you until it has to use friction breaks. While you might be able to squeeze a bit more energy out by varying your speed a bit in the right conditions, it'll be hard trip beat cruise if you want a stay decent speed with lots of regen.

 

[RickLightning]

Cruise control is the best substitute for engine breaking. It will use regen to slow you until it has to use friction breaks. While you might be able to squeeze a bit more energy out by varying your speed a bit in the right conditions, it'll be hard trip beat cruise if you want a stay decent speed with lots of regen.

Breaking and breaks should never be used. Braking, and brakes work much better.

 

[Alan168]

Here's my experience with multiple 40 mile roundtrips we have taken in very hilly portions of Vermont. The results are for driving in Normal mode and 1-pedal mode.

The outbound leg is mostly uphill. I use an average of 9% of battery charge for this part of the trip.
The return leg is exactly the same route, which of course, means it's mostly downhill. I use an average of 3% of battery charge on the return trip.

Therefore on average I use only 1/3 the energy during the downhill leg of the return trip. As they say: "Your mileage may vary", but this might help alleviate some of your range anxiety.

 

[RickLightning]

Here's my experience with multiple 40 mile roundtrips we have taken in very hilly portions of Vermont. The results are for driving in Normal mode and 1-pedal mode.

The outbound leg is mostly uphill. I use an average of 9% of battery charge for this part of the trip.
The return leg is exactly the same route, which of course, means it's mostly downhill. I use an average of 3% of battery charge on the return trip.

Therefore on average I use only 1/3 the energy during the downhill leg of the return trip. As they say: "Your mileage may vary", but this might help alleviate some of your range anxiety.

I suggest you try Sport mode, on the downhill, and see if you use less than 3%.

 

[Ekiehn]

Thanks. I know there are a ton of factors involved with this, slope of the mountain, weight of truck, and finding that right balance where my speed is offset by the friction regeneration. With my last truck, I would downshift and let the engine slow me down so I wasn't burning my brakes, so I'm hoping one of the drive modes will do this for me. Appreciate your comment!

No matter what mode, single peddle gives you the most regen..I have one of the original Escape Hybrids and you could put the shifter in low for a similar effect... wish I had that option over single pedal.

 

[RickLightning]

No matter what mode, single peddle gives you the most regen..I have one of the original Escape Hybrids and you could put the shifter in low for a similar effect... wish I had that option over single pedal.

1 pedal.

 

[Calvin H-C]

I have been guessing that if the brake coach says 100% it means that all braking was done by regen, and if it says 90% then 10% was done by the regular brakes. Is that correct?

Pretty much. Think of it this way: a brake score of 100% means that 100% of the possible recovered energy from braking was recovered.

That word "possible" takes into account the losses and inefficiencies, so those are not part of the score. The energy left over either goes into the battery or ends up as heat in the pads and rotors.

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