The Premier's Limo: 2004 Toyota Prius "winter beater" ecomodding thread

[MetroMPG]

Repurposed from last year's winter beater Civic:

[MetroMPG]

I wonder how long the lettering will stay on. Probably not very long in cold salty/sandy spray conditions...

[oldtamiyaphile]

Originally Posted by MetroMPG

Why? Because under light/moderate braking, the car slows via regenerative braking. The friction brakes are only called into action when the car is nearly stopped, or just moving slowly.

My car squeals it's brakes under light braking at speed. It's the sort of sound you'd get from glazed pads. I haven't have a chance to have a look yet, but thought I'd ask for ideas, if the hydraulic systems isn't supposed to be reacting, I don't know what else it could be.

[MetroMPG]

Well, if I were an engineer, I would design regen so that braking at speed applied the lightest possible hydraulic pressure to ensure the rotor surfaces are always dry & corrosion free.

But from what I've read about the 2nd gen & newer Prius, the friction brakes only come on:

a) under hard braking, when the braking request exceeds regen limits
b) when the ABS activates due to a wheel losing traction or a bump
c) below 7-9 mph, when regen ceases

[Daox]

Looks good Darin. When is the A-B-A coming?

[planetaire]

Originally Posted by MetroMPG

Well, if I were an engineer, I would design regen so that braking at speed applied the lightest possible hydraulic pressure to ensure the rotor surfaces are always dry & corrosion free.

But from what I've read about the 2nd gen & newer Prius, the friction brakes only come on:

a) under hard braking, when the braking request exceeds regen limits
b) when the ABS activates due to a wheel losing traction or a bump
c) below 7-9 mph, when regen ceases

Below 10 km/h you could brake in R mode. Don't use the brake pedal !, just the accelerator one ! The more you depress the pedal, the more the speed will be reduced and at a moment you go backward.
You will have a little more regen. Little because speed is very low.
You could also use B mode under 35 km/h to improve regen. But don't forget to switch back to D mode after.

I am also waiting for A-B-A test, specially with boat tail

[MetroMPG]

Cool! I didn't know that R trick for low speed forward regen. Scary for any car behind you though.

So I suppose you could also get regen while going backward, by shifting from R to D before stopping.

[MetroMPG]

Update!

1) I put insurance on the car about a month ago and have put a couple of hundred kilometers on it since then. Piloting Toyota's hybrid system is as geeky-fun as I remember it. I have to say I'm really, really enjoying the car.

2) Except for the fact that on day one, the exhaust broke right before the muffler. I was going to fix it, but you know what? It's a very mellow sound -- not harsh, not very loud. I've had several people in the car who didn't even notice it.

3) Another modification: I added the EV switch so I can take manual control over when the ICE runs. EG: from my driveway, I typically go down hill less than a block to the first stop, and now I always do this in EV mode. I wait to fire up the ICE until it can make some useful contribution to forward progress, rather than idling along for the ride, getting terrible MPG. It's like taxiing efficiently to the runway before firing up the big jets.

4) This car is really cold blooded! It takes a long time to warm up. I've primarily been using it on fairly short (<16 km / 10 mi.) local sub/urban trips (fetching building supplies etc.), and have only gotten it up to full operating temperature maybe twice in the last month.

5) Fortunately, I discovered the EV switch works like a kill switch in a conventional car. Otherwise the engine would run non-stop until it gets to a predetermined minimum coolant temp, which I'm never going to get to anyway on a typical local trip.

6) MPG so far: 50 mpg US / 4.7 L/100 km for 95% short-haul, sub/urban trips. That's acceptable, all things considered. The Firefly would be good for ~70 MPG in similar use; last winter's '07 Civic beater would have been low 40's, using ICE-off coasting at every chance in both cars.

[MetroMPG]

"EV mode" switch - that's the little white button I added to the car.

It's a simple momentary switch connected to the ECU to give this North American market gen 2 Prius a feature that was unavailable here, but available on the JDM/European cars.

Limited efficiency usefulness... or so I thought at first!

When I put it in, I mostly did it because I thought it would be neat to use EV mode for short distances like moving the car in the driveway, or as a party trick to show passengers.

Ooh, neat! And how far will it go in EV mode?

Everybody wants to know, myself included. So for kicks, I drove it as far as I could from 7/8 bars on the battery SOC gauge until the battery got low enough that the engine automatically fired up.

In mild, dry conditions it went about 1.3 km / 0.8 mi., feather-footing it through suburbia, including 2 stop signs, mixed gradually rising/falling elevation (with maybe a net 5 foot drop from the start), and a max speed of probably 45 km/h.

Of course, using EV mode like that is a terrible efficiency strategy, because once you deplete the battery charge, the ICE automatically fires up regardless of EV setting and then it gets particularly terrible mileage while the engine force-charges the battery back to a minimum level, even when stationary. Mileage in that scenario will be worse than if you'd just driven the car normally the same distance (ending at the same state of charge).

A few scenarios where EV mode can boost efficiency...

- Increasing EV usage before an upcoming significant regen event (eg. descending a long hill).

- Delaying a cold start until the engine is really needed. Eg. I typically go down hill less than a block from my driveway to the first stop, and now I always do this in EV mode. Which means I wait to fire up the ICE until it can make some useful contribution to forward progress, rather than going along for the ride at high idle, getting terrible MPG. It's like taxiing efficiently to the runway before firing up the big jets.

The best use of the EV switch is as an engine kill switch

Wait a minute, you're surely saying. Doesn't the Prius normally stop the engine automatically when you let go of the accelerator?

Sure it does. But it only does this when the coolant has gotten hot enough AND after you've made a complete stop.

But if you're doing a fairly short trip where you know the car isn't going to get up to temp anyway, or if it's up to temperature but you haven't yet had to make a stop, you can use the EV switch like an engine kill switch in a conventional car: ICE-on for accelerating & cruising, ICE-off for coasting up to stops & turns.

My in-town mileage has gotten much better since I started using the EV switch like this.

The main downside? I would have put the switch it in a different location if I'd known it was going to be much more useful than as a party trick. I put it where it is mainly because that trim panel was easy to remove, and I intentionally put the switch lower down so it would be less obvious when I removed & patched it when I go to sell the car next year. It would be much ergonomically better closer to the steering wheel, like on one of the stalks (signal/wiper/cruise).

[deejaaa]

great info.