I noticed in the Owner's Manual that Low Gear isn't supposed to have much effect when accelerating/driving up steep inclines, but is proported to assist in retarding speed on downgrades. On a trip I took this weekend, I did shift down when beginning a steep downslope and found that the motor immediately began charging the HV battery at a greater rate than if I were in Drive and used the brake.

My question is whether downshifting to slow the vehicle in the normal course of driving will put wear and tear on the CVT for which it is not designed (similarly to towing a trailer on a conventional automatic trans in Over Drive) or if this is a legitimate use for the Low Gear. If the CVT is up to it, this seems like a way to milk a few more precious MPG's from the Escape.

art

 

From what I understand, there really is no low gear on the CVT. All it does (again, by my understanding) is to manage the regenerative braking differently - it makes it feel like an automatic in low gear by loading up the generator when you let off the gas. I have gotten to where I keep it in low gear anytime I am in city or stop and go highway driving. Keeps me from having to touch the brake pedal at all and charges the battery better than coasting. My mileage has shot up lately, not sure if this is a factor or not.

According to the book, you can put it into 'low" at any speed. I don't think it has any effect at all on the transmission. Someone correct me please if I am wrong.

Ray

 

Yeah, "low" isn't really "low" at all. On Prius they call it "B" for "braking" mode, it just changes the algorithym to provide more simulated engine braking, but may have a negative effect on fuel economy.

 

I am convinced that my gas mileage has increased by using "low" in city type driving. By letting the regen braking slow me down, I avoid using the friction brakes much. As long as the accelerator peddle is depressed at all, the vehicle behaves the same in "L" or "D".

I would love to see some sort of breakdown on how much braking is done with the regen and how much is with the friction brakes. What I do know is that once the friction brakes kick in, energy is being wasted by generating heat instead of electricity.

 

Hmm. I may try this next time, see how it does. I flirted with it on my street, and was a bit surprised by how fast charging slowed down the FEH.

 

One thing to keep in mind is you really don't want to be fully charged at any time. You always want to have some capacity available in the event you end up braking or if the engine has the possibility of charging the battery by running at a slightly higher (but more efficient) RPM.

 

Why would that be? If the battery cannot take any more change, would not the system would just revert to normal, non-regen-style braking and dissipate the energy as heat, as in most non-hybrid cars? Trying to manually manage your battery charge may be fun for a bit, but it would also add to your driving tasks and become a bother after a while. I am not even sure how you would do it, since your battery charge level is not very apparent from what I have seen.

One other question is maintenance related. Would you rather replace brake pads or the generator/charging system? Over time, in constant L mode, it seems you will work your charging system a good bit more than it might be designed for. Of course, none of us has had an Escape long enough to really test this theory out, but seems there might be a design reason why they have two modes rather than one. Same goes for the Prius I guess, so maybe someone in that forum can speak to the longer term experience.

 

I am curious about that too although I believe that the system is smarter than me. If the battery doesn't need charging then I believe there would be no regeneration and even in L it would just coast. It is an electric motor/generator and to the best of my knowledge, has no parts that wear. I don't think the way I drive it is damaging or accelerating wear but I am very receptive to opinions to the contrary.

I actually like the way it performs in L versus D - when I let off the gas pedal, the regen braking makes it feel like a standard shift car does when coasting in gear.

Is there any way to tell the battery state? Mine always just says avail elec normal ot whatever it is.

 

Something has to manage the current flow - relays or silicon I would guess. My knowledge of exactly how that motor/generator/braking gizmo is implemented is pretty hazy. Just exactly how does pushing on the brake pedal cause the generator to send volts to the battery? Anyone have any details or actual photos/diagrams?

OT is maybe Over Temp, which I think would hurt the battery. I will try out the L mode. Even with the fancy GPS/radio/CD the battery state is not very informative. I guess they think the early adopters come from the idiot light school??? Just for sheer amusement I would like more precise info. That cheesy green display down by the speedo/tach is next to useless IMO.

 

dknapp, the best place to look for detailed information like this would be a patents website such as
http://www.patentstorm.us/,
but several sites have general descriptions of regenerative braking
http://www.hybridcars.com/renerative-braking.html

It essentially works the same way as a windmill electricity generator, converting kinetic energy back to electric energy, I am no expert, so this is just my 2 cents.

Edit: BTW, that hybridcars.com website is excellent for those of you who haven't seen it yet.