EV mode at every stop

Any clue what the gen III threshold is, 25mph seems high to do for efficiency. It may even be lower than waynes 15mph as the bsfc is more efficient at lower power in the gen III. YMMV, the car won't let you accelerate to 25 at every stop light, I tried it, SOC goes low and EV is kicked out. If you have a few fast road stop lights far away you may be able to regen. 25mph on hills seems very difficult too.

I wish I had a force charge button, creaping along in traffic jams the ice keeps kicking off, but I need A/C in the heat. It gives a tiny charge then fires up again. Worst traffic jam A/C mpg 17 and I know the car was lying high.

 

I'm not really sure. While the greater TQ and better low rpm bsfc efficiency could prove helpful I wonder how this compares to the broader EV range in the GenIII. I noticed that when traveling on my downhill commute, I can go down to below 50% SOC before the ICE kicks in. On the GenII 57.5% was the limit. The GenIII also only charges to 60% SOC on average where the GenII charged to 64-65% on average. *shrug* Not really sure what to think. lol

 

Cool, was hoping someone knew, I really can't use EV much, where I want to use it, it kicks out.

The difference in behavior is because of the ICE. Since the ICE in the gen II had less capacity to give power or recharge, a more aggressive SOC could be used on the Gen III.

 

By letting it regen, you are hurting your glides. First Law of Thermodynamics / Conservation of Energy.

For a better DWB (driving without brakes) technique, push the pedal slightly to make the HSI bar disappear (maybe try Neutral a few times to calibrate the nut behind the wheel), and the car will glide or coast better.

This particular regen is a synthetic engine compression drag, to make the car feel more like the regular non-hybrids folks are accustomed to driving.

 

Side track, but they should make that synthetic drag optional, a customizable feature. Would make it a lot easier on everyone if they would just make removing your foot off the accelerator the same as neutral. Everyone meaning hypermilers of course.

 

I don't think even every hyper miler. A great thing would be user settable, no regen, max regen, most efficient regen. Give me steering wheel buttons. That way you can hit max regen to brake without using friction, or no regen to glide. Max regen with accelerator modulation would be my choice for slowing for turns and accelerating out.

 

That is why I called it a hypermiling buffet. Take what you want and leave the rest. Just because the pros perform techniques that you don't care for does not make them (the pros) wrong. ProximalSuns is driving his first Prius yet he is presenting information as if he is an expert. Because this is a forum for information exchange, such behavior requires checks and balances so future readers are not misled. When he has authentic data confirming his belief I will gladly embrace his ideas but until then it is nothing more than speculation that flies in the face of physics (Prius-related) as we currently know it.

I drive in the real world and I use many of Wayne's techniques in a safe manner.

 

Well I do see an EV only switch installed in the vehicle by Toyota. I don't see any warning about using it. So it is fair to say that Toyota feels the EV switch they installed can be used without damaging the car.

With near full time AC, driving fairly normally, 5 mph over the speed limit...I think getting 57+mpg in those circumstances is excellent and I think it is as high as it is due to the use of EV mode as much as the vehicle allows.

Your mileage will vary. I certainly don't want to be the person following Wayne's instructions causing traffic issues and road rage by driving irresponsibly, getting screamed at by other drivers per the video above.

 

Well you'd have to talk Toyota about that as the car is designed to go into regen mode when you take your foot off the gas.

 

I wasn't one of the numerous PriusChat and CleanMPG opinion leaders invited to attend the G3 kickoff events and talk directly to the Prius engineers. So I just had to read their reports afterwards.

Maybe one of your personalities could do the same.

 

EV switch won't damage your car, but where in the manual does it say that EV mode will improve MPG?

The logic in hybrid is that ICE works only in range of best efficiency. In normal mode you get EV mode until you reach 10 kW (maybe less), when you demand more kW from the car, ICE will fire up as this is the most efficient way. The only way I can think of using EV mode is when the car is cold and you want to move it. You must know that if you use EV for acceleration you can not regen the same amount of energy back (on flat road), you will end up with low SOC very fast, and when you do ICE will work in the best efficiency but you are converting mechanical energy through MG1 and charging battery and then you use battery energy to power MG2 (to propel the car) in best possible way you are getting back 80% energy (may someone correct me on that number) and if ICE is charging at 38 % efficiency (BSFC 220 g/(kW·h)) then the overall EV mode efficiency is around 30 % this number is still very good if you compare it to other cars and low power demand.

 

Basically, you're converting chemical energy (either from the battery or the gas tank) to kinetic energy, which is 1/2 * m * v^2. So yes, if you accelerate to a faster speed, it will require more energy. But if you accelerate more rapidly to the same speed, it does not inherently require more energy. There are some exceptions; for example, aerodynamic drag is proportional to v^2. If you accelerate faster, you will spend more time at a higher velocity, so your aerodynamic drag will be increased. However, the main reason to accelerate at a certain rate with the ICE is to use the engine at its most efficient point; the RPMs are neither too slow nor too fast. An electric motor has a very different efficiency curve; various online sources suggest that most electric motors are most efficient at about 75% of maximum load, however the curve is very flat between about 25-100% of load (below 25%, their efficiency drops rapidly).

I've also heard from my Leaf-owning friend that there isn't nearly as much he can do with his Leaf as he can with his Prius when it comes to hypermiling; driving without brakes or just going more slowly are about the only tactics. Accelerating quickly or slowly doesn't make a difference, while pulse-and-glide would probably actually hurt.

So, since the electric efficiency is fairly flat, it doesn't really make a huge difference whether you accelerate quickly or not when you choose to use EV. This isn't a reason to use more EV power - just that if you're using EV power for something, the rate of acceleration probably won't affect the efficiency significantly.

 

So in the real world, it would be much less efficient for me to be driving EV through a flat neighborhood at a speed of about 10 mph compared to about 18-20 mph (both EV)?

 

Probably not. Energy use goes up by velocity to the fourth power, so faster is less efficient (AEBE). Electric motor efficiency vary with RPMs, but not a lot in that region, at 10 MPH, the MG1 is spinning at 1600 RPMs which 25% of it max rated speed. It seems likely the even if the motors are marginally less efficient at 10 MPH, that wouldn't be enough to offset the decrease in efficiency due to increased speed (twice the speed means 16 times the energy required (air resistance portion))

 

I tried to measure how much power it takes to accelerate briskly in EV Mode up to 25mph today. I only had one real chance to test it because I'm rocking a nice tank right now at 67.2mpg and 292.2 miles. I started at 58.8% SOC and after reaching 25mph I was at 54.4% SOC. This was during a left turn so energy may be higher than if I had gone straight. I was only able to recover about 2% SOC by the time I hit the next light. I could have recovered more if I had ended my glide sooner and applied regen braking earlier but that doesn't seem like the most effective way to go. I also monitored load during initial acceleration and it seemed to sit around 86%-90% if you keep the HSI indicator in the last 3/4 of the Eco area. I didn't get more than a few tests in so take these results with a grain of salt.

 

But it is. Once you are up to speed, that kinetic energy has only two places to go ( in addition to ongoing losses), into the batteries, or into heat in the brakes. You want as much as possible to go into the batteries.

 

I'm sorry I should have written that differently. I extended my glide to the point I was crawling to the stop light and in danger of going too slow for traffic coming up behind me. To effectively regen more power I would have had to start my glide later thus using more ICE power for propulsion. This would have provided more speed at the moment I started applying the brakes for regen. Does that make sense? In essence I drove for maximum glide and not max regen at the expense of glide distance. This is kind of hard to explain. LOL

 

Ok. That makes sense.