On first tank of gas and averaging in low 40's, which ain't bad, compared to our older cars that were in the teens.

Still, I'd like to know if there are easy ways to do better.

Our house is 600 feet higher than the valley floor where we do most of our driving. The drive to the valley is generally "free", but we pay coming back home.

Is there anyway to get the Prius to use more of the battery coming up our driveway, which is a 300' gain? (I'd heard that hybrids should not be put away fully charged, especially if they are going to immediately go down hill the next day. Is this true?)

For safety I like to drive with headlights on, and for comfort with the A/C on. Is this killing mileage by much?

 

How long is the drive up? What speeds can you safely use?

Physics is going to pretty much dictate what happens on the hill climb. The best you can do is keep the speed modest, no more than 55 mph, while climbing. However, it may make sense to look at a topographical map of your climb and do a little 'route planning.' Google up topographical map and see if you can get a map of the hill climb route. Then we can discuss it.

As for AC, you may be able to finish the trip with the AC 'off' and let the cabin temperature rise a few degrees. It is your choice but I'd recommend this experiment:

1. flip air source to 'recirculate'
2. turn off AC
3. set fan to a fixed speed
4. see if the cabin warming is delayed long enough to reach home

Bob Wilson

 

Your situation is similar to mine, though the vertical difference is only a couple hundred feet instead of 600. Part of the issue is that your first drive down the hill in the morning really isn't "free" because the Prius is busy warming up the engine, which involves lots of fuel being burned just to get the engine warm. In a way this isn't such a bad thing because if you started from cold on level ground and took off, the car would be drawing feverishly from the battery while it tries to keep from demanding much of the cold engine. I'm sure that doesn't harm the system, but that energy does have to be replaced eventually. This way you're coasting free and adding charge rather than depleting it.

Of course, if it's a steep descent it's likely that your battery is charged well before you reach the bottom. Once that happens the car reverts to friction brakes to dissipate all of that extra potential energy. That's probably where you take most of your FE hit because you burned the fuel to get up the hill and can't get it all back on the way down. The engine's warmup cycle exacerbates this effect because the system uses some of that extra fuel to charge the battery, filling it up sooner.

My solution was to add an EV switch that allows me to delay engine start as long as I stay below 34mph. What I do is drive 3/4 of the way down the hill (maybe 0.7mi worth of road) and then start the ICE ~20 seconds before I'll actually need it. My observations indicate a small (no more than 5%) but noticeable improvement over the course of a 17mi morning commute. I would also say that this is one of the very few situations where the EV switch can be used effectively to improve mileage. Is this for you? Depends on your conditions I guess. If your speed limits are higher than 35mph you might have trouble with the requirement for reduced speeds. You also may or may not be comfortable adding the EV switch in the first place. (Some argue that Toyota might take exception to its presence, although it does nothing more than activate programming that Toyota provided.)

 

Brick, where did yo get the EV switch? Was it hard to install? I was thinking of finding one but, I thought it could be hrd to install or void my warranty. Does it give you good power when going up a climb?
Thanks,
Matt

 

Remember installing an EV switch will reduce the speed you can travel in electric mode from 41mph down to 34mph. I am able to force electric mode without one of these switches by speeding up and taking my foot off the throttle, when I see I'm in electric I slowly power up and keep it 41mph or below. But this only works when I have plenty of battery charge and the car doesn't need more power.

Right now there are 2 types of EV switches, one is like the OEM verson and the other is in the cruise control stalk. If Toyota finds out you used one of these and you have battery warranty issues they will deny your claim for the U.S. version of the Prius. So the cruise control version is probably the way to go. Niether version will give you the dash light showing you are in electric mode.

http://www.sigmaauto.com/jdm/prius/prius0405.php
Sigma has the OEM version, is complicated to install, is expensive and a dealership will know you have it but looks OEM like the Japanese Pruis.

http://web.mac.com/gagix/iWeb/PriusMods/EVButton.html
Here is an example of how someone installed their OEM switch.

http://www.coastaletech.com/electric_only_mode.htm
Coastal Tech has the cruise control version, is easy to install, is less expensive but a dealership won't know it's there.

 

I think Resist covered your other questions so I'll get this one.

I **DO NOT** use EV mode for primary propulsion. 10mph in a parking lot, yes. Coasting down-hill, yes. Accelerating from a stop, no. That's the ICE's domain.

The Prius has very limited battery capacity and it runs down real quick if you do something like climbing a hill. And max acceleration in EV is very slow. The good news is that the Prius protects the battery and you in the event that you need more acceleration. Get on accelerator in EV mode and the ICE turns back on.

 

One thing you have to remember is that the electric mode was never designed as a hill climber. You can even have trouble backing up a hill, so parking in San Franciso can be an issue. Reverse is electric only for all Prius vehicles.

 

It does not sound like the EV switch give you many options that my car does not have anyway. The mai advantage I can think of is controling when your warmup happens. This is one of my problems, rolling up to an intersection to stop and wait for traffic. Is this the main advantage of the EV switch?

Thanks,
Matt

 

The main advantage is lets say you park your car in a parking structure and don't want to pollute it with exhaust fumes or noise. Or you are creeping along in traffic and don't want the engine kicking on and off. You may know your route and want to use as much EV as possible because up ahead is all down hill, where you can get the juice back for free.

There are many uses for EV mode. The only reason our version does not have the same Japanese EV mode is because of the warranty here. That much use would certainly kill the life of the batteries sooner than 150,000 miles/10 years. I am sure though that the next version of the Prius will make much more use of EV mode with bigger batteries and plug capabilities.

 

This is not correct.
The EV switch mode is canceled at 34 mph, but it does not mean you can't go in electric mode above 34 mph.
You can still go in electric mode up to 41 mph with EV switch installed.

Ken@Japan