Long Distance Creeping (now with pictures)

[TonyPSchaefer]

There are three speed "bands" when coasting at speeds lower than 40, assuming the ICE is off:

• At speeds from 40 down to 8 mph, regenerative braking occurs.
• At exactly 7 mph, there is no shown energy flow between the wheels, the motor, and the battery.
• At speeds from 6 down to 1 mph, the battery propels the car.

I have become intimately familiar with these numbers because my regular commute has a 4-way stop with a line of cars that can extend a mile. No joke. On average, it's about a half mile. On a good day, only a quarter-mile. But since it's a 4-way stop, the creep averages speeds lower than 7 mph.

I have tried just about everything to get all the way through with more than just 2 or 3 bars on the battery. Many time, though, the SOC gets so low that the ICE starts kicking in. As you can imagine, I get a little angry when I just sit there in an idling car. To make matters worse, the two miles following this quagmire has a 50mph speed limit. After sitting in that line, the cars behind me don't want to wait as I recharge my pack. Since it's single-laned, I usually suck it up and have two of the worse miles of my entire drive.

What I've found to work the best is to pulse-stealth with a shift into neutral for gliding. This would work better if I could glide farther without hitting the back of the car in front of me. And I don't want to wait while it gets too far ahead because the car behind me will get antsy.

Some days I'm tempted to just get out and push. I would if it were the Hybridfest MPG Challenge.

So here I am asking everyone if you have a similar situation and how you handle it. Or if you have any ideas or suggestions.

[Ichabod]

I have sympathy for you.

I'm assuming you've considered the possibility of a different route, and I don't think it would be legal to install pneumatic grapplers on your car to latch onto the car in front of you.

Maybe turn off as much of the electronics as possible, including MFD... and for the short pulses, actually try to make sure the ICE comes on instead of stealthing.

OR... petition your local government to change the traffic sign at that intersection to something that makes more sense for the road's use. You could probably walk down the line of cars collecting signatures some morning to back you up. It might actually work.

[hobbit]

Lean on your selectmen to get a proper roundabout installed
at that intersection. The backup will vanish.
.
_H*

[TonyPSchaefer]

Originally Posted by Ichabod

... and for the short pulses, actually try to make sure the ICE comes on instead of stealthing.

Yeah, I tried that. Priapus ended up slipping into MG-whatever where the ICE wouldn't shut off until I came to a complete stop and then with a shudder. Since the creep sometimes lasts for several meters before a complete stop, the ICE ends up running and mileage tanks fast.

As for the round-about you and Hobbit talk of, this would be the ideal location. It's perfectly in the middle of nowhere with plenty of room for expansion. Unfortunately, it's a remarkably safe intersection. I have never seen an accident there. And sadly that's the only thing that seems to get action.

[Jim1eye]

Originally Posted by TonyPSchaefer

Unfortunately, it's a remarkably safe intersection. I have never seen an accident there. And sadly that's the only thing that seems to get action.

Maybe you can get a blind guy to hang around the intersection. They seem to want to get things done when nothing's happening.

[Bob64]

Is it level or uphill?

I'd try leaving a bigger gap and start timing the stop n go traffic so you don't have to brake. If possible, get an ev button so you can kick that ICE idling into off.

[usbseawolf2000]

This is where the solar panel becomes useful. It can avoid your mpg killer situation. I am talking about next gen.

For this gen Prius, creep in D and glide in N is the best I came up too.

You can leave home 15-30 mins earlier and that should improve the situation. You can control the time and traffic varies with time.

How far is this 4-way jam from you home? If it is close by, I would start up and let it warm up until the ICE shuts down. This way, the battery can be as full as it can. It is better to idle during the warm-up than during stop-n-go.

If the trafic gets gradually worse as you close in, to this 4 way jam, don't let the car go into S4 stage. S4 drains the battery pack quickly by raising amp draw before the ICE starts. Stay in S3 and use EV button to shutdown the ICE. Accelerate in S3. This will preserve battery juice for your a mile creep.

[timwalsh300]

Originally Posted by usbseawolf2000

If it is close by, I would start up and let it warm up until the ICE shuts down. This way, the battery can be as full as it can. It is better to idle during the warm-up than during stop-n-go.

Can you expound on this?

Tim

[Danny Hamilton]

Since you're referring to a stop sign where there probably aren't many 18-wheelers, creep distances are a car length or more, and creep speeds may need to be a bit faster to avoid upsetting other drivers, I can't help much with advice with your particular stop and creep situation.

However, I have a daily 40+ mile each way expressway commute, and with the expressway construction throughout the Chicagoland area over the past couple of years combined with the occasional nasty accident, I've occasionally encountered multi-mile stop and creep situations on the expressway.

In these situations, I try to position myself in front of an 18-wheeler. Many of them seem to prefer a large following distance wich allows me to creep a bit slower without seeming to annoy them. Then I can creep slowly (sometimes just dropping it from neutral to drive without touching the accelerator pedal), allowing the space in front of me grow, and drop into neutral when I see brake lights 3 or 4 cars in front of me. As I'm neutral coasting and the 2 or 3 cars in front of me accelerate into their hard braking, the buffer temporarily grows a bit faster and then with them stopped I coast into that space. It is especially great when the next creep begins before I've completely covered the buffer. I get to just keep on neutral coasting as they begin to accelerate away again. I've noticed that the 18-wheeler behind me is frequently behaving similarly. Letting a bit of a buffer grow between min and me before he even begins to accelerate, and then slowly coasting into this space as traffic up fron hits their brakes.

I suppose leaving a 2+ car-length gap in front of you before creeping and then trying to time a slow enough neutral coast into this space such that as you close the gap to a yard or two the vehicle in front of you is moving away again, allowing you to extend your neutral glide, isn't a realistic plan?

If not your options are rather limited by physics. You need to use some form of energy for the sum total of the accelerations between when to firt stop until you pass through the stop sign. You've already indicated that an ICE acceleration won't cut it and pushing isn't an option. This only leaves the battery. You've already made it clear that your creeps are required to be too slow to get any regen, and that you are limited in how far you can neutral coast.

Assuming that taking a different route isn't a realistic option, the only variable you seem to have any control over is the sum total of the accelerations. The more distance you can cover in each neutral glide, the less total number of times you'll need to accelerate.

It would be interesting to count the number of times you accelerate. Do this for a few weeks, and you can compute an average number of accelerations from various initial stopping points. Then you can challenge yourself to try and reduce your number of accelerations against those benchmarks. In the same way that small changes slowly add up to higher MPG, you may find that small subtle changes in the way you handle the situation slowly add up to fewer accelerations.

Example, perhaps repeatedly letting the gap in front of you grow too large to avoid needing to accelerate twice will annoy the driver behind you, but you may find that letting that gap grow large just once each trip is acceptable to you. This shaves one acceleration off the benchmark. You might even find that you are comfortable with letting that gap grow once when you first stop and again when you are 2 or 3 cars from the stopsign. Now you've shaved 2 accelerations off the benchmark.

Watch for situations where it seems reasonable to let that gap grow just slightly more than typical (the car behind you is leaving a larger than typical gap, or the car in front of you is accelerating more aggressively than the other vehicles around you). That extra few feet might just make the difference between an extended neutral coast or not once or twice per trip. Combine this with the inital and final extended gap, and you may shave 4 accelerations off the benchmark.

Thats all that comes to mind right now, but you may find that when you are focussed on trying to shave just one more acceleration off the trip on any given day, you discover other reasonable and novel methods.

[TonyPSchaefer]

Originally Posted by Bob64

Is it level or uphill?

I'd try leaving a bigger gap and start timing the stop n go traffic so you don't have to brake. If possible, get an ev button so you can kick that ICE idling into off.

It's pretty level. Of course I leave the gap and avoid braking. But since the creep at at <6mph there's a constant draw from the battery. This is where the "pulse in D, glide in N" comes in. I have the EV button and it doesn't help because, as I said, I work to avoid ICE-on anyway. Besides, this is a perfect situation in which an individual can use the EV button to intentionally drain the pack to unnaturally low levels.

Originally Posted by usbseawolf2000

For this gen Prius, creep in D and glide in N is the best I came up too.
You can leave home 15-30 mins earlier and that should improve the situation. You can control the time and traffic varies with time.
How far is this 4-way jam from you home? If it is close by, I would start up and let it warm up until the ICE shuts down. This way, the battery can be as full as it can. It is better to idle during the warm-up than during stop-n-go.

Yeah, D-to-N is so far the best I've found but even it falls short some days.
This is on my drive home and I've started leaving closer to 4:30 but here in Chicagoland traffic starts backing up much earlier than that. Even on the side streets. What I said above about "on a good day it's only 1/2 mile" was referring to lighter traffic situations.
By the time I reach it, I've driven several miles, gone through warm-up, glided, stealthed, all that. The ICE and CC are warm and the pack is ready.

I should add that the route leading up to this intersection is primarlily <40mph and also heavy with traffic. But with more favorable conditions. So charging the pack leading up to the intersection is usually difficult. So I start creeping with 4 or 5 bars at best.

I think today I'll try shutting everything off as Ichabod suggested.