Discussion in 'Toyota Prius Plug-in' started by SocialSuzy, May 17, 2012.
I haven't paid for electricity yet. Consumers Energy Chargepoint station I frequent is free.
The PiP's battery is only 4.4 KWh in size, of which only 3.3 KWh is usable for EV. The SOC range is from ~18% up to 85%. EV part of is from 25% up to 85%. The rest is reserved for HV usage. The built-in charger is only 2.2 - 2.3 KW. That's the max that the car will pull from the wall, even if plugged into a 3.8 KW or 7.2 KW EVSE. Takes ~3 hours to recharge at 120V and ~1.5 hours at 240V.
For me, who has to pay upwards of 34 cents a KWh, it makes sense to plugin as long as gas remains above $3.50 (which isn't hard in California). We're in the midst of getting solar installed, so my KWh cost should drop dramatically as soon as the system is turned on. I should end paying about 13 to 15 cents a KWh. So, basically no matter what, it's worth plugging in for me. Especially since I get HOV access in CA again, and I'm getting way better gas mileage than my old 2005 Prius.
Agree that people should, in general, be reporting both energy and gas used, though sometimes depending on what one wants to emphasise MPG is a fine measure -- its not about energy efficiency its about energy independence and how little gas one used. Of course John should have known better (since they Op was complaining about wanting all EV and not getting it, so saying something about 75MPG was both off topic and also misleading.
The point about it only making sense if pricess.. depends on if you mean financial sense or ecological sense. If you can pay extra for green electricity it makes ecological sense. I have paid extra for green power for years.. and that never makes financial sense either. If you want financial sense, don't buy a new car.. don't buy a car at all -- use a bike or public transit.
And even from a financial point of view, the 11 miles in a PiP is about 3kw, which at the say .15c (above average but not crazy), so the toal is .45c for 11 miles. 50 miles a gal (generous since it a short trip) that is .22 gallons or $0.77 at your proposed 3.50 a gallon. Its not even close;it is 1.71* more expensive to use gas as the fuel. Electricity would have to be about triple the national average for it to be cheaper to use gas -- and that is using a cheap $3.50 gas.
But I don't think Social-susi was complaining about the cost.. she paid the primium for the car to drive mostly the greener EV way.. and does not want it using gas on short trips. Unfortunately for her, that does not seem to be viable.
The SOC for the Plug-In battery ranges from about 20% when "discharged" and operating only in HV mode, to about 81% when "fully charged". The Toyota engineers have already programmed in giving up some EV range for the sake of the battery lifetime.
And in California, 30 cents/kwh is a good average number for the cost of electricity. You can get it cheaper (about 15 cents/kwh) by getting time-of-day pricing and only charging during the lowest rate period. At least those are the numbers for Northern California (PG&E). I am not taking into account those who have solar panels.
I agree: huh?
Not to argue semantics, but you are using the real world 50mpg which includes all losses and not an ideal "1 gallon of gas = 33.4kW" and then you assume you are getting 11 miles for 3kW. You are not including the loses of the charging station, the inefficiency of charging the 3kW to the battery might have been 4kW from the grid.(ie. you pay what the meter says)
3.67miles/kW is 11miles and 3kW
1.5miles/kW is 50mpg
I would suggest there might be something wrong with using 11miles and 3kW. It probably uses more power, only because of the EPA numbers of 33.7 kilowatt hours of electricity is equivalent to one gallon of gasoline and Toyota states 90mpge/50mpg. So it should be something more like 2.7miles/kW on EV only. I suspect you are using more than 3kW to actually go 11 miles and it might draw from the hybrid SOC (so the wall recharge plus some extra from the HV battery).
^^ IIRc people report ~ 3.2 kwh from the wall. If you pay 15 cents a kwh, then the 11 miles cost 48 cents. This works out to 4.36 cents a mile for fuel.
Calculations attempting to compare miles/kwh between electric and petrol are all over the place because it depends how you made the electricity. Wind ? PV ? Oil ? Coal ? NG ?
the source of power only matters when you add $ to the comparison. The miles/kW is a measure of the MG2/ hybrid efficiency
You seem to have a some misunderstanding of the data and processess.
The 33.7kw in a gallon is the total energy, not what the vehicle can effectively use. The Prius has a very efficient engine, but there are still limits. The electric motors are far more efficient tank-to-wheels than an ICE. But then one as to consider how the eletircity was generated.. if its renewable that's great and very efficient to the wheels. But if the eletricity is from coal.. then the inefficiency for the EV mode is "upstream" and still roughly comparable.
I used real-world for both EV and ICE of the Prius. You were arguing about converting costs, not theoretical efficiency models.
The 3kw is what people are using the charge the PiP from the wall. Like all EVs, the Pip does not use the whole battery, so the 4.4 total size is nto what matters, it is the 2.5 or so that is usable.
The EPA measurement did use some gas in the 11miles of the test.. about .02gallons (it can be estimated from the 95MPGe. (not the 90 MPGe you suggest)
The EPA testing process is pretty clear about testing the state-of-charge during testing, so its not eating HV battery.
Its an Hybrid/EV.. your Milage Will Vary.
Many users get far more than 11, and some, as discussed in this thread, are getting less and trying to understand why. Your discussion is not helping them.. if you want to debate efficencies, start a new thread.
Oh and I'm not a PiP owner.. I drive a Volt.
Here is my experience--and perhaps it will shed some light on how a PiP owner can get incredible MPG but at the same time wonder about EV miles.
You are all correct. The way you drive and the terrain are important factors. I am an experienced Prius driver (easy acceleration, etc)--but I mostly do short trips within 10 miles RT. In addition, because of the need to cross a creek, much of the time I do a steep downhill followed by a steep uphill at both the start and end of the trip--although the rest of the terrain is flat. My starting EV range is always around 9.1 miles - and that's pretty close to what the range turns out to be.
From reading your posts, I have concluded that the initial EV readout will tend to be low if you mostly run on EV. The hills also affect that readout, even though the regeneration downhill negates much of the subsequent uphill.
I guess I expected a little better actual EV range.
Still, because I know I'll get home on EV, I don't use any of your strategies on the hills. On longer trips, I will use HV to conserve 1.5 miles of EV before getting close to the downhill/uphill ending because the engine will not (even with everything else off and verrrry slow uphill driving) let me get below about 0.7 EV miles on that last uphill without turning on the ICE.
I still question whether my battery is giving me what it's supposed to because--when I drive in a different direction (away from the creek) and there is never a significant elevation change...and when on long trips where I drive using your suggested HV/EV strategies--both my initial EV readout and actual EV miles remain pretty low compared to what you other owners are posting.
And that's how an overall MPG in the (quite amazing) 130 range can still leave a PiP driver with just enough concern to ask the dealer about it at my next service and wonder aloud on the forum.
Thanks.. that was a good description. It helps you say both estimation and real range are low both with the hills and when going on the flats.
I will note that regen is not perfect.. the measurements we've done on Volts suggests maybe 80-85% efficient at low speeds (which is darn good) in what goes into the battery then there would be loss again in using the battery. So the hills always hurt, loss in regen and higher-demand going up hill means higher loss for the same speed.
Second is the algorithm for estimation. While there are no published descriptions from the manufactures its been well documented by multiple drivers in the Volt that the estimation algorithm depends on multiple days of history, but is weighted more heavily on recent data. Seems it the same for the PiP, as a few people commented it takes days to get it back to where it was after they take a long trip. (Taking a few days in the begining is different as it may include driver learning).
For the Volt, one of most telling experiments on the battery issue was two drivers swapping cars and driving their normal route with a different, logically identical Volt. While there was a change, the actual "range" went mostly with the car not the driver. see Let's swap cars and see if mileage goes with the driver or with the car...... These cars have hundreds of cells and even a single cell being weak can cause a problem (because it impacts the other cells in the series) can increase stress, see Battery Life and How To Improve It. Even if the quality is very high, say 99.999% are "perfect" with hundres of cells per car, and thousands of cars, the odds are some weak cells exist in cars which could limit their range.
Testing for weak cells is very hard.. but time amplifies the problem which may be why there are some, but not all Leaf's showing signs of degradation.
So its quite possible there are PiPs that get more and some that get less range, even with exactly the same driver and path.
More importantly for you now is that weak cells now only accelerate the pack degradation.
Ask your dealer for a 1-day swap and measure real (not projected) range and see fi there is a difference.
dcdave, here is an easy experiment to try when you have an hour or so: charge your car, shut off all climate controls, put it on ev and eco, set a trip to 0, note your starting 'range', find a reasonably flat area to drive between 20 and 40 mph. if you can't do 14-15 miles before the ice comes on, i believe there is something wrong with your car. if you can, your car is fine and it's the terrain you typically drive or climate controls or driving style. many here try to get the posters who think there is something wrong to do this type of experiment, but most would rather ignore and complain.
Have you taken into account the fact that when you coast to a traffic light, no energy is consumed by the pip, thus the mileage accumulated during this coasting effect is added to the total mileage traveled, thus giving you the impression EV range is more than the estimated EV range?
Just to take that a bit farther.. since DCdave is in hilly country, one should be able to hit HV when leaving the garage and still a "full charge" once you get to flatlands.
If the energy to get up to spead was EV, then its proper to count those as EV miles. And regen to battery from EV is also EV, HV mode up a hill and down may do regen into battery but counts the miles as HV so its fair. What matters is what was the orginal source of the energy.. so the only "cheating" is going up hills in HV and then switch to EV mode for regen on the down hill. That will artificially inflate the EV, both by putting more chareg in the battery (wich is indirectly from the ICE) as well as making the "EV" miles seem to have a very low kWh/mile rating as they are all downhill miles.
I think your facts are a bit off kilter,altho the car is rated at ~4.2KW it generally charges to about 3 KW. I often come home with 5 to 6 miles left, so my costs are even less. Where and how the HV portion is being charged, I am unsure of, the EV portion is definitely a charge station, home or otherwise. If the HV is being charged while driving while in EV, THAT is BRILLIENT,
I see you have a Prius, you should test drive the PIP, it is amazing!
But, EV is more than what you see on the dash and it is inevitably more no matter how bad a driver one is. Why because One must stop from time to time. If you are a good driver or have ideal topography the results can be impressive. Regeneration is not a impression, but a FACT.
Just to clarify the OP and people questioning EV mode range. The PIP is only rated for 6 miles all electric. If you get 11, then great. The 95MPGe assumes 0.2 gallons of gas. The 11 mile range is including plugin + gas. You can see clearly on the sticker only 6 miles of all EV.
Also note that the 0.2 gallons of gas at 50mpg would be 10 miles of range. Obviously starting and a cold ICE means you get more like 15-25mpg when not warmed up, plus some losses with the ICE wanting to charge the HV battery.
So anyone claiming over 6 miles is getting a bonus.
So the math above was wrong and it really should be 6 miles for 3kW (or 3.3kW) which will only make sense if gas goes above $5 or your local electricity is very cheap or you get free ChargePoint until they start charging.
You obviously dont understand how the EPA test works.
Separate names with a comma.