Consumption Screen

[maggieddd]

Gee, I know, I know, you must be thinking, wow she is soo soo dumb. OK, fine I am dumb. But can you explain to me exactly what each thing means on the consumption screen. What is good to get and what is not?

[efusco]

First part, what's each "thing":
1)bars--the average mpg averaged over 5 minutes. Quite meaningless in stop and go traffic or when the speed is changed frequently, but nice for observing trends for mileage over time and as you experiment with technique.
2)Car/leaves-these show how much energy you've regenerated one car/leaf is 50Wh of energy. This takes into account braking and coasting (any green arrow).
3)Miles--how far you've gone on that tank
4)MPG--average for the tank so far
5)bar on left--your instantaneous mpg--lags about 2 seconds behind reality.

Part II--What's good/bad.
1)Car-leafs: It is 'bad' to try to accumulate these. ideally no leafs with no stops and no regen would be perfect. But, they're good to see in real life b/c in real life you have to stop and when you stop it's better to regen than to waste the energy as heat to space. It should not be a goal to get more of these..I, in fact, try to get as few as possible. If you look at the screen shots of the 1400 mile marathon guys they have 3 or 4 partial car-leafs per 30 minutes.

2)high 5 minute bars are good, low are bad. Sometimes you'll have low bars if you only drive a little way in a given 5 minute period but then are stopped for the rest (like at a drive-though window or something), and that should not be considered bad b/c you 1 minute of 50mpg driving is then averaged over 5 minutes and will show a 10mpg bar.

I think you can figure out the rest.

[maggieddd]

Thanks for the explaination.
I guess what I was confused about were the bars. I thought high bars were bad because I thought they represented gasoline consumption and I thought that the less leaves I got the worse. I've been getting partial leaves and thought I was doing bad.
I do understand the average MPG and miles drive, but these were the only 2 things I understood on that screen ops: I guess I am doing OK.
So ultimately, I should be aiming for high bars all the time with as little leaves as possible, correct?

[Sid]

<snip>

Part II--What's good/bad.
1)Car-leafs: It is 'bad' to try to accumulate these. ideally no leafs with no stops and no regen would be perfect. But, they're good to see in real life b/c in real life you have to stop and when you stop it's better to regen than to waste the energy as heat to space. It should not be a goal to get more of these..I, in fact, try to get as few as possible. If you look at the screen shots of the 1400 mile marathon guys they have 3 or 4 partial car-leafs per 30 minutes.
<snip>.

I'm not sure I understand why it's "bad" to regen, if this didn't happen wouldn't then the ICE have to run to charge the Hybrid battery, thus using gas?

[kirbinster]

Have to disagree to some aspects of the regen leafs being bad. It all depends on the traffic and the terrain. When I drive to work I try to make sure that I regen going down the steepe hills so the SOC is a max when I get into town, that way I can run EV all the way through town. Conversely, going home I use the EV down to a low SOC in my development as I know in the morning the engine has to run to warm up anyway. This approach maximizes my mileage. But the concept of no electricity is valid in a perfectly flat world with no traffic, lights or stop signs. In our world, regen is good, and in some cases a lot of regen is very good.

[altaskier]

I'm not sure I understand why it's "bad" to regen, if this didn't happen wouldn't then the ICE have to run to charge the Hybrid battery, thus using gas?

Regen is bad - it's just less bad than not having regen.

Ultimately the energy stored in the battery comes from the gas engine, either directly by siphoning part or all of its output to a generator, or indirectly by recapturing some of the kinetic energy of the car when you hit the brakes. The problem is that the capture, storage, and reutilization of this energy is not 100% efficient, so you only get a fraction of it back to use for propelling the car. The good news is that you do get some of this back, while in a normal car when you hit the brakes you just dump energy into heating up the brakes. You're also helped because the energy per gallon extracted by the gas engine is improved at moderate versus low output which you can exploit in a hybrid by capturing some of the excess.

Think of cruising along a road with mild, undulating hills. If you had a car free of all friction and wind resistance, your speed would oscillate from a minimum at the top of hills to a maximum at the bottom of hills, and you would be able to coast forever. If you instead hit the gas as you climb and hit the brakes as you descend, you have to put in energy as you climb and you recover it when you descend - but you recover only part of it so the net result is that you have to supply energy. Of course in real life you have additional losses due to wind resistance, friction, and the annoying fact that the people behind you would rather not have your speed oscillate from 15 mph to 80 mph depending on whether you're at the top or bottom of the hill...

[kirbinster]

That is a fairly good explanation. And to take it a step further, it also explains why the Prius gets good mileage in city driving. One key advantage is that at a traffic light the engine turns off (if it was running). This saves a lot of fuel. The other is that instead of wasting energy to the brake pads each time you have to slow you recapture some of it. If you are able to anticipate your stops you can actually go for quite a while without ever starting the ICE -- you really get unbelievable gas mileage when you burn no gas

[efusco]

It's a spectrum:
Best to worst.....
No regen, no friction braking (ie all gliding) -> Minimal regen, no friction -> Lots of regen, no friction -> Lots of regen, lots of friction -> No regen, lots of friction

[TJandGENESIS]

Wow. I am learning a lot here...but I need to get the basics...REGEN...ICE....these things are almost foreign to me...

Let me put this out there. Can you just drive the car, with little thought, as if it was a 'normal' car? Or do you have to pay attention to all the REGEN and stuff.

I'm not trying to sound stupid, and frankly, it sounds like something a geek like me will enjoy, but on the other hand, I don't always want to 'babysit' the car. Sometimes, I just want to, you know, drive.

[Tideland Prius]

You can just drive it. Try driving with the screen off for a tank and see if you do better with it off. Some people do =)