Not all hybrids created equally

[MasterAlex]

I was just wondering if anybody knows the sure answer for this or not.

I've heard that all hybrids do EOC automatically. Does anybody have any proof for this because I know for a fact that my 2005 HCH does not, do I still need to put it in neutral and turn off the engine to get better results?

[SVOboy]

I'm pretty sure only the prius and the FEH stop the engine automatically, but I haven't been up on the new two-mode stuff in all the GM trucks.

[Red]

Far as I know the only way for a Gen 1 or 2 IMA system to EOC is if you are in neutral and are below 18-20 MPH. Anything faster and the ICE stays on

[jamesqf]

Originally Posted by Red

Far as I know the only way for a Gen 1 or 2 IMA system to EOC is if you are in neutral and are below 18-20 MPH. Anything faster and the ICE stays on

Not strictly true, at least in the Insight. You need to be below the ~18 mph speed for the engine to stop, but if you're on a hill you can then coast up to a fairly high speed (45 mph is as high as I've been), I think until brake vacuum drops.

Coincidentally, I was just doing this tonight on the way back from the lake. There's about 10 miles of 6% downgrade, which is being repaved so there's a 40 mph limit in the one-lane sections. I normally go about 55-60 down it, in gear with regen. With the paving, there were a couple of spots where traffic stopped (or nearly so), which put me in autostop. When it started moving, I just eased up on the brakes, and soon was rolling along at 40, still in autostop.

I don't think it's much of a gain, though, since I normally would have been in fuel cutoff, and getting regen. This is probably true of most hybrids - you may coast a little further, but OTOH you don't get regen - and in these parts most hills are steep enough that you can be in gear with regen, and still need to brake a bit.

[MetroMPG]

Coasting is still more energy efficient than regen. Regen is more efficient than friction braking.

[MasterAlex]

Originally Posted by MetroMPG

Coasting is still more energy efficient than regen. Regen is more efficient than friction braking.

well if you have a battery like mine you have to recharge it after you turn on the radio practically.

This goes back to that 100 hypermiling tips (the one about breaking) wouldn't it be more efficient to break and keep it charged then try and accelerate later while the car tries to recharge it?

[PaleMelanesian]

If you can avoid assist on the accelerations, you don't have to regen to recharge it. I know how hard that is, though. Honda was very aggressive on the assist logic. You think about pressing the pedal, and it assists from the battery pack.

I believe the GM 2-mode hybrids to have a electric-only mode (mode 2). That puts them in the same class as the Toyota and Fords.

The 06+ Honda hybrids have a very low friction mode that the engine goes into instead of completely detaching it from the IMA. It's maybe halfway there to a full electric-only mode, and a definite improvement over the first gen system.

[MetroMPG]

Originally Posted by MasterAlex

This goes back to that 100 hypermiling tips (the one about breaking) wouldn't it be more efficient to break and keep it charged then try and accelerate later while the car tries to recharge it?

That ranking was based on the assumption that you had a fair amount of control over how much you were pulling OUT of the pack, so you could use it sparingly (and therefore have to recharge sparingly). I've only driven the Toyota system, personally. From what PaleMelanesian says, maybe your car's system is harder to control.

But I'd still bet that if we had two of your cars, and one driver maximized coasting while the other employed regen, the coaster would get better MPG, regardless of when & how the computer decided it needed to recharge.

[PaleMelanesian]

43) The most efficient way to slow down

When you *have* to slow down, here's an approximate heirarchy of methods, from best to worst.

1) coasting in neutral, engine off (ie. roll to a stop);
2) coasting in neutral, engine idling;
3) regenerative coasting (hybrid vehicles)
4) regenerative braking (hybrid vehicles)
5) coasting in "deceleration fuel cut-off" mode (in gear, above a certain engine RPM)
6) conventional friction braking (non-hybrid or hybrid)

Choosing the right method depends on traffic conditions (following vehicles) and how quickly you need to stop.

I didn't say it earlier, but I do agree with this ranking.

[MasterAlex]

that brings be to another question then, EOC is dangerous (not going to do it on the freeway) but how bad is it for your car and what about just putting it in nuetral?

Also, will the scangauge monitor while the engine is off?