Regen braking non adjustable ? Deal breaker for me.

[metroshot]

.........
Modern locomotives have something similar to regen except there are no batteries (other than 64V starting batteries)to dump the current in to. It is called dynamic braking and there are giant resistors on the roof that they dump the current generated in to dissipate as heat. Blowers send air over the grid resistors to cool them off. In order for regen to be consistent over all states of charge and battery temps they would need to supplement with friction brakes or add grid resistors like locos to dissipate the energy generated.

Never knew railcars had this !

 

[GaRailroader]

Never knew railcars had this !

Locomotives not railcars. The railcars just have air brakes but engineers prefer to slow the train with dynamic braking only to preserve their air.

 

[EV Trek]

Like a lot of things with the Slate it could change before it goes into production and starts shipping to customers.

 

[jmason]

Yikes! That's just what I want in a brake system: unpredictability.

Having different braking performance depending on the battery charge level sounds like a recipe for disaster.

Yeah, good thing a braking system is still standard equipment 🙂 the only EV I drive that does’t display this behavior is my BMW CEvolution motorcycle which has good regen and I hardly ever use the brakes so I guess that’d make it a 1T?

Anyway, most EVs scale back regen whenever the battery is at FC. Not that unusual or scary in my experience.

 

[KevinRS]

Like a lot of things with the Slate it could change before it goes into production and starts shipping to customers.

If they are planning on showing off production units on the 24th then nearly everything is probably locked in at this point, they are just waiting another 10 days to show us the details.

 

[Tom Sawyer]

It is called dynamic braking and there are giant resistors on the roof that they dump the current generated in to dissipate as heat. Blowers send air over the grid resistors to cool them off.

New idea for the AI image thread.

 

[phidauex]

Some buses used to use a similar braking system called a driveline retarder - they had big coils around the driveshaft and banks of magnets on the driveshat itself. By connecting more and more resistors in parallel with the coil it would act as a generator and magnetically slow the drivetrain. The resistors would heat up and were cooled by mass and air. Very helpful for things like school buses in mountainous regions, you could click the retarder on one or two clicks while descending the mountain and not have to touch your brakes!

Most EVs handle it pretty gracefully, and blend braking as needed. Even my MachE still has plenty of regen at 100% battery, in part because 100% on the display is not a true 100% SOC chemically (this is virtually always true in EVs). This lets it still have a little headroom for some regen. Now, if you charged to 100% and immediately started descending a mountain maybe it would run out of regen space and switch you to all friction, but in 60k miles I haven't noticed the phenomenon.

 

[EV Trek]

As long as it is strong enough to hold my speed going down mountains without touching the brake I will be happy.

 

[Tom Sawyer]

Even my MachE still has plenty of regen at 100% battery, in part because 100% on the display is not a true 100% SOC chemically (this is virtually always true in EVs).

Not my Model 3. When I charge it to 100%, I get no regenerative braking and use the standard friction brakes (pretty much like any other car.)

 

[GaRailroader]

Not my Model 3. When I charge it to 100%, I get no regenerative braking and use the standard friction brakes (pretty much like any other car.)

Same

 

[Sneetches]

Sounds like you want blended braking like the new Bolt has. You hit the brake pedal and it uses regen first and then the brake pads if necessary.

 

[Ronnie]

That seems like it would be very disconcerting the let off the gas and coast when expecting regen to slow or stop you. It would be nice if letting of the gas was always just coasting, and stepping on the brakes activated regen , and as more braking is needed start bringing in the friction brakes.

I do not own an EV so this will be a first for me. I have riden in a Tesla many times, and i recently drove a chevy pickup a short bit with one pedal driving. Reminds of hydrostatic drive that is typical on mowers, and some tractors, even some railroad track equipment. So i am used to one pedal in that way. But it these cases it is always the same no oh we are full so surprise no brakes today...

 

[phidauex]

Not my Model 3. When I charge it to 100%, I get no regenerative braking and use the standard friction brakes (pretty much like any other car.)

Well, that sucks. I do think most EVs retain some regen even at 100%.

Honestly though I don't think it will really impact most people most of the time. I rarely charge to 100%, and even then, it is usually because I'm on a trip and immediately jumping on the highway. By the time I have to slow down, I'm already down a few %.

Blended regen on the MachE works close to perfectly - I've tracked brake system pressure on actual drives, and I can routinely drive over an hour on regional roads and highways without the friction brakes engaging even a single time.

 

[phidauex]

That seems like it would be very disconcerting the let off the gas and coast when expecting regen to slow or stop you. It would be nice if letting of the gas was always just coasting, and stepping on the brakes activated regen , and as more braking is needed start bringing in the friction brakes.

What you describe is a typical 2 pedal drive mode - letting off the "gas" results in coasting, or a very mild regen (aiming to feel like engine braking on a normal ICE car). Pressing the brake pedal engages regen first, then as you press harder, blends in friction brakes as needed.

1 pedal drive works the same way, it just allows for more powerful "engine braking" when letting off the gas, and unlike even a high compression ICE, it will allow you to come to a complete stop (usually right at 1-2mph it will apply the friction brakes just to bring you to a hold).

We don't yet know the logic on the Slate, but I'd be surprised if it differs much from this standard mode.

 

[metroshot]

Sounds like you want blended braking like the new Bolt has. You hit the brake pedal and it uses regen first and then the brake pads if necessary.

Neat concept!

Does the Bolt have that jarring lurch when you take your foot off the throttle ?