Having read the EV mod posts, I am wondering if there is a consensus about how much it actually saves. I understand that there are times you want to avoid the ICE going on for other reasons, but what is the actual mpg savings if any?
If you've actually read most of the posts about the EV mod you'll see the concensus is that the EV mod will not, likely, save you any gas and is more likely to lower your fuel economy unless used exactly right in very specific situations. It's a nice novelty and it has some nice uses from time to time. But it is not and never was designed to be a fuel saving mechanism. Do not install one unless you're prepared to cover the expense of battery replacement if it should die prematurely.
actual benefit: -X% (Negative benefit of ?%) why? Because 100% of the energy comes from gas. Gas -> Motion -> electrical -> battery (chemical) -> electrical -> motion = huge losses in energy as the conversion processes is NOT 100% efficient.
Somewhat accurate, but not completely b/c it fails to take into account the benefits of being able to shut down the ICE from as much as 1/4 mile or more away from a stop when you're in stage 3a or 3b but below 35mph...a situation where normally the ICE would run the entire time until you arrived at the stop sign/light and then another 5 seconds until it shut itself off. It also fails to take into account the lower efficiency of stage 1 and if you're simply moving the car across a parking lot or out of the garage to wash it where engaging EV mode will save gas that would have been burned for such a short move. Using EV mode to accelerate or in lieu of the ICE when maintaining steady speed is not efficient, but when decelerating to shut the ICE off it can offer benefits. As I said above, the situations are rare and specific, but they do exist, so the formula stated is not so simple to apply here.
The biggest benefit seems to be the ability to move the car out of the way in a driveway. I was thinking though about adding the mod, thinking it would be nice on my way out of work to not use the ICE until I get out of the parking lot at work.
That's actually not a great way to use it. Remember that in Stage 1 the ICE doesn't want to exceed about 1275rpm...that's quite low power and low speed and almost all your propulsion is coming from the battery. Thus, in a parking garage it's best to go ahead and let the ICE start, get itself through stage 1 and maybe even into stage 3 before you exit the garage. That way you're ready to go with a fully warmed up car when you hit the main street. If you delay stage 1 with the EV button then need to accelerate to the speed of traffic immediately upon exiting the garage your fuel efficiency will be very low as you'll force the ICE to run at a higher RPM than it wants to during that initial warm-up. Trust me, I used to use my EV button just that way, but with CAN-View to watch the performance I'm convinced it's better to allow the normal warm up under the lowest stress conditions as possible.
+1 on the accelerating out of EV mode, it is not economical and takes the charge down on the main battery way too fast. Best used sparingly, I installed it about a year ago and have used it maybe a dozen times. It has it's place, not a gas mileage saver in the big picture though.
So basically in Stage 1 the car prefers to just warm up the engine at a low running speed, and uses more Battery then ICE to propel the vehicle. This does make sense and would help explain why when I leave my house and come out of my neighborhood 25 MPH speed limits my first 5 minute bar is always above 25MPG even on a cold engine, but when I leave a store and get on the highway almost immediately the first 5 minute bar is well under 25MPG and that is with a somewhat still warm engine. I think Dr. Evan knows everything about the Prius and one of these days I'm going to actually play you on xbox live..
Far far from everything, but even my thick skull has managed to absorb a bit over the past 4 1/2 years! I don't do much xbox live...but we should do something one day just to say we did.
Cost of EV switch $65 Gas saved over lifetime $2 Frustration from never getting the d*** thing to work when you want it to (-) Priceless
As the OP, thank you all for clearing that up for me. Dr. Fusco, as always was very clear and informative and DocWillie summed it up very nicely (and cleverly). I think I will skip the EV. Now I have to figure out the difference between CanView and Scangauge. I'll research before I ask.
The main difference, now, is that you can't get CAN-View but you can get scan guage. Norm's quit selling the CAN-View except for those doing plug-in upgrades to their Prius.
Hi Sweetguy, I think you should rethink the EV switch. I had mine installed last October (Hobbit did mine). It is very simple to use. It also works great. I use it 90% of the time as an engine kill switch. Many times when the ICE doesn't shut off because I am not in stage 4, the EV switch will shut the ICE off.
i installed it for free, i only use it to get down to the main road, its like 1000 ft away, then i drive at like 45-55 mph all the way on my commute, then when i reach my destination, i engage EV mode in parking lot, it probably doesnt save much, but i just feel its really cool, im sure if my 01 prius had a EV mode switch it could travel farther than the 05 prius on battery
I would like to comment some... - As everyone said there is no magic here, the EV switch does not produce any MPG improvement unless you undestand how it works. - We know heavy use of battery power lessen your fuel economy. - A Pulse&Glide technique tells us do not use the battery power for the best results. If you understand better how Prius works, you'll see better and better MPG results. Ken@Japan
every penny that turns into gas and drips into the ICE that I can savfe is worth it. You don't know how much I hate to hear that engine fire up for no reason at all. As sson as it's warm and wants to shut down I'm where I want to be and turn it off anyway. I might as well drive a honda civic.
I use my button all the time to force the same kind of shutdowns that I *would* get if I was in stage 4, but before I get there. I think that usage, i.e. allowing the engine to run efficiently or not at all just like normal P&G, contributes quite a bit to overall system efficiency. Note that it doesn't mean I'm leaning on the battery any harder than I normally would. . The other problem with the delayed-ICE-run scenario, i.e. waiting to light until you get out into traffic, is that since you're entirely on the battery during stage 1 warmup you're sitting there pulling 80 amps out of the pack trying to get the car to scoot. Best to let it go through that first minute under very light load conditions -- if you've got a short stretch of road you can normally drift slowly along without bugging people, or a downhill, go for it, but if you're diving straight onto an interstate or secondary highway, back-time what you do accordingly so the car's really ready to deliver when you ask. . There are *numerous* threads about this in the archives... . _H*
EV button is standard here. I use it in very limited situations. 1/ Showing off when I drive past work mates in the work compound. (Remember turn off AC, it's noisy) 2/ Back out of my garage quietly at 6.00AM 3/ There is no 3. Why not just let the car manage itself? I don't want to buy a new traction battery so I won't stress the one I have. Using EV might save a few cents worth of petrol but it *may* stress the battery and cost you several thousand dollars. I'm not saying the battery will fail tomorrow after installing a EV switch but why for a few pennies worth of fuel would you play at that casino table? Little to win and lots to lose. While it is advantageous to Toyota to get the most miles from each gallon of fuel you buy it is counter productive if that comes at the cost of reliability. I prefer to allow the computer programs to do their work unhindered.
