Chevy Bolt EV Forum banner

1 - 20 of 44 Posts

·
Registered
Joined
·
117 Posts
Discussion Starter #1
Hey guys.
My first technical post.
Sorry if it has already been been discussed.

For those who did not "meet me" I currently own 2014 Fiat 500e.
I live in MI (Lansing area) and would gladly meet someone who has Bolt and is willing to spend some time with me learning the car.

Anyway, my questions are below.
Scenario - state of charge 50%, temp + 20 C (say +70 F). That means perfect conditions for the battery.
Start driving, full power is available.
If you drive in L - car will slow down on its own using regen. It will even come to a complete stop.
Question 1 - would depressing the brake pedal ADD regen? Say L in deceleration creates 25 kW return flow. You depress brake - would 25 kW become 45 kW?
Same scenario, but you are in D, coasting.
Questions 2 - how is the brake pedal adjusted? Initially regen only, no regen at all or a blend?

Same scenarios as above, but temperature dependent. Say, cold day, -10 C (+15 F). Battery pack is cold as well.
Question 3 - How much regen, if at all, is allowed?

And any other comments.


Now, a few info on Fiat.
It has P R N D. No L or such.
When decelerating - it is coasting with small regen that depends on your speed. About 25 mph you will see 3-4 kW, at 45 mph 6 kW, at 60 mph 7-8 kW.
If you touch the brake pedal, regen will increase up to 60 kW (that's the highest I ever noticed). However, the brake pedal is a blend of regen and friction.
Also, on cold days the regen amount is limited until battery pack warms up a bit. It is not conditioned - at least I did not notice. When plugged in it will warm up to 68 F or so and then starts charging at full speed.
The regen works despite of battery SOC. Meaning, it automatically charges to 100% (there is some buffer) and you start driving, at 99% you can still regen at about 8 kW.
That's about the shortest summary of it.

How is it with Bolt?
 

·
Registered
Joined
·
1,044 Posts
I believe if you hit the brake pedal it is a blend of regen and brakes. I don't remember the last time I actually hit the brake pedal though. I drive in L and use the regen on demand paddle on the left hand side of the steering wheel. This seems to be able to handle 99% of my braking needs. I also haven't seen any reduction in braking with regen unless I charge the car to 100%, which hasn't been over a year. I live in a mild climate and it hardly ever gets below 0 Celsius. I have seen limited regen on my Tesla in colder weather, but I don't ever remember seeing it on my Bolt. Cold weather drivers can assist you better!
 

·
Registered
Joined
·
3,532 Posts
This topic has been discussed fairly extensively, but I'm still unclear about your question about D mode and regen. Some say it's blended right from the outset. My understanding was max regen is achieved with a combination of L mode and the regen button on the steering wheel. My assumption is that max regen could also be achieved with the brake pedal alone. I'll see if I can dig up that old thread that lists the various regen energies.
 

·
Registered
Joined
·
117 Posts
Discussion Starter #4
I'll see if I can dig up that old thread that lists the various regen energies.
Thanks, that would help a lot.

My point, basically is, to drive it like a regular car. Meaning, in D, take off foot - it will be decelerating with some regen. Then, if I must slow down faster, touch the brake pedal to let regen increase, but not use friction yet.

Not that I am after hypermiling, although I averaged 165 MPGe in my Fiat on summer, in city (Lansing area), but I want to make sure that the regen is activated from the brakes as well. Not like Tesla - one pedal driving only and brakes are friction.

Why?
Well, picture this. You loose about 10% of energy when accelerating. To charge, you loose another 10% (via EVSE). If you look on energy flow, to get up to speed and use on average 40 kW for a several seconds, you return maybe 25 kW (that is using regen only).
That is why I want it to coast and use the brake pedal to regen only when needed.
Hence, coasting is the most efficient way of driving it.

Oh, no I do not want to keep pulling the paddle on the steering wheel.
 

·
Registered
Joined
·
1,262 Posts
That is why I want it to coast and use the brake pedal to regen only when needed.
Hence, coasting is the most efficient way of driving it.

Oh, no I do not want to keep pulling the paddle on the steering wheel.
This has come up here dozens of times and it’s still incorrect.

Just because “coasting” may have had some benefit in last century ICE operation does not mean it has even the slightest benefit when driving a Bolt

The usual justification is, as you stated “But I/my spouse doesn’t want to bother to learn best science BEV operation.” Your car, you’re the driver, but don’t expect universal agreement here on coasting being the most efficient way of driving a BEV.
 

·
Registered
Joined
·
1,044 Posts
My point, basically is, to drive it like a regular car. Meaning, in D, take off foot - it will be decelerating with some regen. Then, if I must slow down faster, touch the brake pedal to let regen increase, but not use friction yet.
I used to argue that driving in D was more efficient than L, but I was wrong about that. Put the car in L and get used to one pedal driving. You modulate the regen by the accelerator. One pedal driving is absolutely amazing and efficient. There has been talk by some people here in permanently taking the regen paddle and permanently having it active. I thought about this myself.

We have many old threads about this and it is discussed in excruciating detail. Once you get used to driving in L you will understand why even Tesla copied the Bolt in one pedal driving. BTW, why do you want to drive your Bolt like a regular car? It isn't a regular car, it is so much better!
 

·
Registered
Joined
·
3,532 Posts
This reignites previous arguments. Without question, coasting is more efficient than regen and later acceleration, and it's something I would want in any vehicle. That said, you can probably get close enough to a coast driving in L mode.

I'm a bit weird and shift to N in the Prius when coasting just so I don't have to modulate the accelerator to get near to coast. I suppose you could do the same in the Bolt, but I don't think it makes enough of a difference. Maybe you'd get an extra 1/8th mile of range with extreme effort? Probably not worth it.

My biggest concern about getting used to L mode is losing the muscle memory of modulating the brakes in an emergency.
 

·
Registered
Joined
·
12 Posts
Once you get used to driving in L you will understand why even Tesla copied the Bolt in one pedal driving.
The world's top selling all-electric cars in 2014 were the Nissan Leaf (61,507), Tesla Model S (31,655), BMW i3 (16,052), and the Renault Zoe (11,323). Accounting for plug-in hybrids, the Leaf and the Model S also ranked first and second correspondingly among the world's top 10 selling plug-in electric cars.[117] All-electric models released to the retail customers in 2014 include the BMW Brilliance Zinoro 1E, Chery eQ, Geely-Kandi Panda EV, Zotye Zhidou E20, Kia Soul EV, Volkswagen e-Golf, Mercedes-Benz B-Class Electric Drive, and Venucia e30.


Global sales of the Renault Zoe, released in 2012, achieved the 50,000 unit milestone in June 2016.[126]
General Motors unveiled the Chevrolet Bolt EV concept car at the 2015 North American International Auto Show.[127] The Bolt is scheduled for availability in late 2016 as a model year 2017.
Wikipedia

Seeing as the Tesla S was being sold in 2014 and the Bolt was not available till 2016 it is hard to see how Tesla copied from GM. I don't know much about the Model S but I owned and drove a 2014 i3 BEV and one-pedal driving is just how the car works. No putting it into low or other adjustments it just works that way.
Don't get me wrong, one-pedal driving is a great feature of electric vehicles but it annoys me that the "late to the party" (Nissan and GM) claim to have invented it.
 

·
Registered
Joined
·
1,805 Posts
This reignites previous arguments. Without question, coasting is more efficient than regen and later acceleration, and it's something I would want in any vehicle. That said, you can probably get close enough to a coast driving in L mode.

I'm a bit weird and shift to N in the Prius when coasting just so I don't have to modulate the accelerator to get near to coast. I suppose you could do the same in the Bolt, but I don't think it makes enough of a difference. Maybe you'd get an extra 1/8th mile of range with extreme effort? Probably not worth it.

My biggest concern about getting used to L mode is losing the muscle memory of modulating the brakes in an emergency.
Someone mentioned that letting the Bolt coast in N is a bad idea...
 

·
Registered
Joined
·
253 Posts
Letting any car, ICE or EV, coast in N is a bad idea. Automobiles are designed to be controlled via the active engagement of a drivetrain with the wheels of the automobile. Coasting in N is something usually reserved for penniless surfers who are trying to milk every last fume of gasoline on their way to the next rumored site of some gnarly sets.
 

·
Registered
Joined
·
1,262 Posts
[QUOTE="redpoint5, post: 528882, member: Without question, coasting is more efficient than regen and later acceleration, and it's something I would want in any vehicle.

I'm a bit weird and shift to N in the Prius when coasting just so I don't have to modulate the accelerator to get near to coast. [/QUOTE]no matter how many times an incorrect statement is repeated, it’s still incorrect.

The fallacy above is that L is an ON/OFF switch; full regeneration followed by acceleration. That some choose to drive that method only applies to their preference. Those who’ve learned to use L mode to best advantage know it offers the most precise control of vehicle speed available today

I’ve driven all the Tesla, BMW i3, Leaf, Jaguar, et,al. They’re catching up, but none are as good at one-pedal as the Bolt was when introduced in 2017.
 

·
Registered
Joined
·
1,805 Posts
We need Yoda to train all these new drivers on how to Use the L. Hybrid drivers need especially more training. Glide and coast is not the best strategy for an EV. :)
 

·
Registered
Joined
·
3,532 Posts
The primary reason I got into the habit of shifting to N in the Prius is that the engine kicks on if you exceed 61 MPH, but if you put the car in N beforehand and let the downhill accelerate the vehicle, the engine doesn't kick on. When you've got between 11 (winter) and 16 (summer) miles of EV range, you end up doing everything you can to maximize it.

We need Yoda to train all these new drivers on how to Use the L. Hybrid drivers need especially more training. Glide and coast is not the best strategy for an EV. :)
Pulse and glide is a technique that maximizes the power delivered for the quantity of fuel burned (Brake Specific Fuel Consumption) by operating the engine in most efficient torque and RPM range, building up speed, and then coasting down to some lower threshold speed.

That's different than a technique of driving the average speed of heavy traffic (allowing space to increase and decrease between the car ahead). Not expending energy in the first place is always more efficient than expending it and then trying to gain it back with regen, granted that difference is made much smaller in hybrids/EVs.

Likewise, it's more efficient to coast to a stop rather than maintain speed all the way to the braking point. It's a small difference in the scheme of things, and you need to be considerate of traffic behind as well.
 

·
Registered
Joined
·
721 Posts
This reignites previous arguments. Without question, coasting is more efficient than regen and later acceleration, and it's something I would want in any vehicle. That said, you can probably get close enough to a coast driving in L mode.

I'm a bit weird and shift to N in the Prius when coasting just so I don't have to modulate the accelerator to get near to coast. I suppose you could do the same in the Bolt, but I don't think it makes enough of a difference. Maybe you'd get an extra 1/8th mile of range with extreme effort? Probably not worth it.

My biggest concern about getting used to L mode is losing the muscle memory of modulating the brakes in an emergency.
Trust me, you WON'T ! ;)
I drive in L ALL the time, I don't even use the paddle.
I won't buy another EV with out it ! So I guess I am stuck with the Bolt ;)

@PLP, forget what you can gain back when regening. It is not worth the effort to think about---- UNLESS you live in the mountains. Then you will see it .
 

·
Registered
Joined
·
305 Posts
The Bolt gets a lot of praise for the way the engineers implemented "L mode", and rightly so, but how about some praise for good old "D mode".

I always drive in L by myself, but my wife complains that she feels a bit nauseous when I drive in L (perhaps my driving style :p), so I drive in D when she is in the car. It's amazing to me that D truly feels like a traditional ICE vehicle when braking while still using a good amount of regen and then friction brakes on top of that.
 

·
Registered
Joined
·
1,262 Posts
The primary reason I got into the habit of shifting to N in the Prius is that the engine kicks on if you exceed 61 MPH, but if you put the car in N beforehand and let the downhill accelerate the vehicle, the engine doesn't kick on. When you've got between 11 (winter) and 16 (summer) miles of EV range, you end up doing everything you can to maximize it.
How a Prius drives has zero to do with how the Bolt drives. Why keep coming back to this?

Likewise, it's more efficient to coast to a stop rather than maintain speed all the way to the braking point.
Not in a Bolt. One more time, the Bolt isn’t a Prius. In a Bolt in L, one can drive for weeks without ever needing friction braking. Slowing to a stop is done completely with regeneration.
 

·
Registered
Joined
·
59 Posts
The specific reason why it's a bad idea to coast too far in the Bolt is because it turns off the oil pump that lubricates the gearbox. That's a real, solid, financial reason to avoid leaving the car in "N" for very long.
I can't speak to how the '17 and '18 function, but the '19 Bolt will NOT shift into neutral while driving.
 
1 - 20 of 44 Posts
Top