Pulse and glide versus stealth. Explain please ...

First off, watch the Energy screen so you can see the status of power flow.

"Stealth" is a single mode when the car is running on battery only, with arrows flowing out of the battery to the wheels. Kinda cool to do to show off to your friends, but not the most efficient way of driving. It's also helpful for very short drives (e.g., through a parking lot or around your driveway) where it might not be efficient for the ICE to light for such a short distance and duration. The battery isn't big enough, and the car is not designed, for sustained stealth driving. The car does it on its own for brief periods, but to try to force it for any length will cost fuel economy; the ICE has to run to recharge the battery.

Pulse and glide is a combination of modes. The pulse is modest acceleration with arrows flowing from the ICE to the wheels, avoiding any battery use. The glide is a no-arrows state induced by totally releasing the go-pedal and then feathering it back down slightly. It is roughly equivalent in a conventional car to putting it in neutral and killing the ignition, allowing the car to freewheel.

P&G is done at speeds <40 MPH. Pulsing can be done at any speeds, with more power to overcome aero drag required at higher ones, but no-arrows glides are pretty much limited to the lower speeds.

Neither ICE-off glides nor stealth will happen until the ICE has completed most of its warmup cycle. Until then the Energy display may mislead you into thinking the ICE is off. You might give a listen with the music off a few times to get a sense of when it's running. And for further study on the warmup process, see this.

 

Oh, I just let you go first. :heh:

Brian, your paraphrasing of our (carefully thought out) posts is pretty much spot on. Here's one other thing that might help you during a pulse: Keep the instantaneous MPG at least half the vehicle speed. This will help keep ICE RPM out of inefficiently high ranges.

As for hills, it depends on the incline. On a gradual incline, P&G is still feasible. The steeper it gets, the less practical P&G becomes. I normally just aim to keep ICE RPM in efficient ranges during a climb. If a downhill precedes it, I use a glide to gain speed to help carry me up the other side, then allow speed to fall off during the climb as needed. All of this assumes staying safe and legal, of course.

As for "B" mode, limit its use to long, steep downhills as a substitute for braking. Think of "B" as engine braking, sort of like a jake brake on a semi if you're familiar with that. And on that subject, here's more for you to digest. :thumb:

Finally, for your 1-mile trips, that's still too long to try to run in stealth mode only. The car probably wouldn't cooperate anyway. The lower the battery charge, the more difficult stealth mode is to attain. "Short distances" here means maybe a few hundred feet at most and where power demand is low, as in the examples I provided previously.

 

Evan, I'm getting faster on the trigger, but dammit, you did it again. :fish:

Brian, you ever had two men fighting over you before?

 

That's correct, for pulses.

It takes a little over a minute to move from S1 to S2, and it seems more dependent on time rather than temperature; it's pretty consistent across various outside air temperature (OAT) ranges.

The S2 to S3 transition is an exact temperature: 70F (158F). So obviously, the warmer the OAT the less time it takes. In the heat of the summer, 2-3 minutes may be all. At the other extreme is the dead of winter with cabin heat running full blast. I've never timed it in that scenario (largely because I don't allow it -- see below), but my semi-educated guess is 10-15 minutes.

Many of us use modifications to help shorten that interval -- namely, an engine block heater and blocking the grill. A good search around PC will give you lots of info on either. The EBH especially is effective, safe, and easy to use (though the install is a bit of a pain) if you have somewhere to plug it in. With the grill block there is at least a theoretical concern of overheating the engine, electric motors, or inverters, so that's probably best done only in the coldest of weather unless you can monitor temperatures under the hood.

Finally, I try to avoid running cabin heat in the winter. It really robs the engine of heat. It's easy to pull ICE temp back down into S2 ranges, and with that you can no longer glide. I've seen ICE temps drop by as much as 20F just sitting at a long red light.

The S3 to S4 transition is neither time nor temperature dependent. Instead, it requires that curious "idle check" (as some call it), where the car has to come to a stop with the ICE running, sit for about 7 seconds, and the ICE spontaneously stop. It can happen as soon as the car hits the 70C S3 temperature threshold.