I've seen similar things about the Ford Escape Hybrid which would make one think it is ALWAYS all electric to a certain speed (20 MPH or something) then the ICE kicks in. Simply not true.

Sad but true fact: the writers and reviewers aren't necessarily knowledgable nor do they all care. I saw a web article where the auto reviewer effectively said you could get 10 to 20 MILES on electric only in a Prius. No way unless it is all down hill. I wrote to him so he could correct it. 1 mile in good conditions, MAYBE 2 in perfect conditions. He replied but didn't change the article. It was still there on the web a month later, intact and incorrect for all to read and believe.

In a Prius, and I assume a TCH, you CAN get to 20 MPH (or higher) using only electric (in D, not R ) if you are REALLY light on the accelerator and IF there is NO 'up' component. But in REAL driving, the ICE is going to kick in almost immediately, like at 1 or 2 MPH. That is actually the way you want it to work most of the time. Let's say you want to get to 35 MPH (~51 ft/sec) and maintain that speed. Which is more efficient, using electric to get to 35 MPH then ICE to stay there because you drew the battery down or the other way around?

Consider Newton's second law of physics, reduced for basic computation:
Force = mass * acceleration

• Using weight of TCH & driver = 4000 pounds
• Constant acceleration of 5 MPH from 0 to 35 MPH in 7 seconds, traveling ~205 feet.
• I made up a constant acceleration value of .25 MPH to overcome air and rolling friction. Since it is 'lost' energy, it results in no net change to the acceleration, and therefore velocity (speed).
• By the way, without a fairly steep hill or a switch to force EV, there is NO WAY you could achieve a constant 5 MPH acceleration.

Assuming a level surface and nothing to make you stop or slow down:
From 0 to 35 MPH:
4000 * 5.25 * 7 = 147000 units to go ~205 feet.
Once at 35 MPH:
4000 * .25 = 1000 units to go ~51 feet or 357 feet every 7 seconds.

You can use 147,000 force units from the battery to go 205 feet, then the ICE kicks in to maintain 35 MPH because you have depleted the battery.

OR

You can use 147,000 units from the battery to maintain 35 MPH for 147 seconds traveling ~7500 feet.

You probably won't have to travel 7500 feet on ICE at 35 MPH to replentish the battery to where the car will use it but it is going to take a heck of a lot longer than the 205' you got using the battery at the start.

Running the ICE to get the required 1000 force units is horribly ineffecient, otherwise all vehicles would get great mileage at 35. Even an 8000# H2 would only need 2000 units/second in this example though I'm sure the air and rolling resistance is MUCH higher. That is why ICE only vehicles get better mileage at 50 MPH than 25 MPH. Full hybrids are 'flipped' because they can get some 'free' distance with the engine off at lower speeds.

You might have situations where EV first IS better. Say as soon as you get to 35 MPH you will hit a long downhill where you will be coasting, braking or even in 'B' mode. You might be able to refill the battery without the ICE needing to run at all.

One place on my commute where I force EV has 4 stop signs about 200 feet apart in a 25 MPH zone. For any reasonable acceleration, the ICE will kick in. Not at all efficient so I use the battery and probably about a 3 MPH acceleration. The next section is somewhat downhill so it ends up being 'coast and car initiated EV'.

 

Droid,

I agree with it all. I've also found that the ICE is more likely to stay running at 30 than at 40 mph. I like your last idea. Often times I'll have someone slow in front of me causing an inefficient slow acceleration. What I'll often do is let off the gas, coast and let them build up some more speed before continuing my acceleration.

 

Yea, hate those slow accelerators too ... Just 30 seconds behind one of these guys feels like forever because the FE gauge's bad news...

 

Do I get some sort of prize for initiating such a lively thread?

Also seems to be the most interesting, most informative, and most fun!

 

I read an article in the newspaper about a month ago that said Toyota might improve on the hybrid by designing it so you could actually plug in at night so that it will go farther on the electric motor before the ICE kicks in. You wouldn't have to plug it in but you could if you want extended EV mode. While it sounds like a great idea, I love the convenience of not having to plug it in and don't know if I would do it. But then again, for better gas mileage, I probably would....

 

Unless they have a bigger battery I just can't see where I would want to pay for electricity to charge this. I don't have to drive very far when I leave the house to get my charge up to GREEN (Usually within 4 miles of driving). When I leave my house I have two options. To the north I have a hill and the battery doesn't help much. As I go down the hill I almost always end up with a green charge. If I go south into town, I can pretty well pulse and glide all the way.

Now if they had a charger at the mall or some of the work places where you could start out with a green while you're already in town, OR for those of you that live in a flat area where you start out in EV mode that might help. I just don't think it would add a lot of value for most people considering the battery / ICE balance thay have designed into the TCH.

 

The TCH is already taking a big hit in trunkspace because of it's traction battery. Unless there is some big change in battery technology they will need even a larger battery to support a plugin model. This has always been the problem with EV vehicles. Where to put the batteries.
J

 

This has always been the problem with EV vehicles. Where to put the batteries.

I noticed on the Ford Escape it appears the battery pack lays flat. I would have preferred a less deep trunk and flat batteries rather than the upright behind the seat package we have. It would have been handy if the TCH had both seats fold with a more usable pass though area. ( Maybe even a hatchback opening?)

 

Isn't the TCH traction battery sort of "L" shaped? Verticle against the back seat and also flat under the far front of the trunk? I'm going on the memory of some pics I saw somewhere. I could be wrong on this.
J

 

I've also heard about the plug in hybrids too. Space of the batteries is a big issue, along with the weight. But if technology proceeds to the point of not having to increase the battery size very much then this is going to be a fantastic breakthrough.

The problem with EVs (think GM's EV1) is that they only go 60 - 90 miles. That's way more than enough for most people's daily needs, but is a deal killer for a long trip. With a plug in hybrid you would get about that much mileage on electric alone. It would produce no emissionss and the per gallon equivalent cost of electricity is about $0.60 per gallon. I read that statistic, but have no way of verifying it. Most of the time 60 - 90 miles is sufficient for a daily commute, but on long trips or days with lots of driving you have a regular hybrid to continue your trip.