TonyT
Sorry I wasn't clear. The original Prius system and battery only uses 50% of the recommended battery cycling for the NiCds. An additional battery pack would function however you desired, depending on what control system you use to connect/disconnect the aux battery system from the Prius battery system. The only "trick" is that the Prius system simply sees a higher voltage, which is identical to a "charged" state of the original battery voltage, so that with the aux battery connected it continues to prefer using the battery capacity over ICE power. Once the original and aux batteries are flat, it will simply continue using more ICE power as per usual. Nothing needs to be changed on the Prius circuitry when modding it this way.
As munter pointed out the extra batteries don't really effect the original batteries, unless of course you don't manage them properly and end up connecting them together when one is charged, and the other discharged. This will result in high currents that could damage the batteries and vehicle. It is necessary to balance the cells before connecting the cells.
BTW the economics are derived purely from the cost of installation versus the reduction in running costs. As posted above depending on your driving profile, urban or country, the effect of extra batteries could range from considerable to nothing. Tell me roughly how many km's you do in either, and what range from base you need and I can give you some pointers.
Posted Wednesday 27 Jul 2011 @ 5:08:03 am from IP #
We live at Crafers in the Hills close to Adelaide.
The daily commute to Adelaide is 40km round trip, for an annual total of 8,000km but the variation in elevation is significant.
For each trip from the house, the elevation increases continuously by 140m over the first 3km along the dirt road at an average speed of 50km/hr (to the Post Office) then the elevation drops continuously by 500m over the next 17km along the freeway travelling at 100km/hour.
The return trip is the reverse.
The vehicle could be charging at both ends after each 20km trip.
Add 4,000km/yr for longer trips at 100km/hr on weekends and on holidays to total 12,000km/year.
Goal is to maximise overnight charging of the car battery at home using domestic electricity.
Friends report that the continuous change in elevation travelling along the freeway at 100km/hr reduces the L/100km performance from their Prius.
I suspect that the optimum sized battery may be expensive and too large to fit within the car.
PS
Assembling an electric car kit could be an interesting project !
Please will you provide links to the electric car kit for $US15,000.
Posted Wednesday 27 Jul 2011 @ 9:47:11 pm from IP #
They are looking at starting sales sometime this year. Very well designed conceptually. Most parts are interchangeable, so only a low part count needs to be kept as eventual spares. Plus the inside suspension system is superior in performance, adjustability and reliability. Tubular chassis houses the batteries, it also supports all the suspension, drivetrain and steering components and provides rigidity regardless of vehicle body used.
An interchangeable body could easily be realized. A ute, van, coupe or RV could all use the same drivetrain underpinnings.
Add a small DC diesel genset like this for a serial hybrid with range limited only by fuel tank capacity. Can be placed anywhere in vehicle body underside with a simple cable and fuel connection only. Note this is a 26kW pancake DC alternator attached to a 2 cylinder Steyr intercooled turbo-diesel, with Air-con and water cooling for heat recovery. This model is from Polar Power inc.
Run off vegeoil for RE. Run house from same genset when plugged in. Charge batteries from household PV during the day and use EV battery capacity to run house at night, or buffer larger AC loads, or even export on peak to the grid at work...
I have some links to better pancake style DC motors and KERs type flywheels if you are interested.
On your commute with a Prius:
The height difference will increase consumption, a lighter vehicle would offset this, but your 100kmh transit speed on the 17km of freeway is the real killer for an EV. The Prius would use about 220Wh per kilometer at those speeds (100kmh) so 17 x .22kWh = 3.74kWh, but only about 140Wh for each km on the 3km section, so 0.42kWh for the slower part of the trip. Plus another 2.04kWh to lift the 1470kg vehicle (incl driver and fuel) up 500m.
Some of this will be reclaimed by rolling down the hill, but only a small amount, about 50-70m by the regenerative breaking. So say about an extra 1.6kWh for the hill climb. So all up you would require about 5.8kWh per trip of battery, to allow for 80% efficiency, about 7kWh. This would need about 10kWh of lifepo4 batteries, cycling them at 70% will give you 3000 cycles, and cost about $2500 for the batteries. So 60,000kms before you need new batteries. Double the battery size to get back home at night without a recharge at work.
A charge would cost about $1.75 at 25c/kWh. (Even PV will cost you over 10c/kWh.)
Thats about $8.75 per 100km. Plus $4.10 per 100km for the extra battery cost alone (no wiring or install or switchgear etc for the mod)
So about $12.75 per 100km...
The Prius would probably use about 4.8l of fuel for the same trip, which is nearly half price at $6.72 at $1.40l of petrol. The problem is that the Prius is already efficient at what it does! (IE +34%) Make some ethanol instead!
Hope that helps.
Regards
JB
Posted Thursday 28 Jul 2011 @ 5:12:52 pm from IP #
A Yaris that uses 5 liters is about 5 x 9.7 / 100 so about 485Wh/km. I doubt it would consume that much on that run though, especially at 100kmh. The gen2 prius and the Yaris have identical 1.5l engines, although one runs on the Atkinson cycle, the other on the normal Otto cycle. The Prius is much more slippery though, and will have less drag and be able to regenerate charge instead of heating normal brakes. (this depends on the driver!)
The efficiency of the Yaris I do not know, this would depend on the Wh/km figure consumed by drag, drivetrain and combustion losses. I have that for the Prius but not the Yaris. The Prius has a 35% drivetrain efficiency. Which is high. Typically petrol engines are not better than 25% eff. just on the combustion side. The other problem is that most drivable engines are most eff. at 80% throttle. The Prius uses a low torque engine, as the electric motor is very high torque from zero revs, and can sustain various different revs across a broad vehicle speed range. This speed de-coupling allows it to get the fuel consumption down, by optimizing engine output regardless of load.
Diesels cheat a bit, diesel fuel also has a higher energy density, but the available low torque results in a slower running smaller engine with higher fuel:air ratios. Hence 1200bar common rails. A small petrol engine needs a electric motor to assist with the torque to keep the car drivable, thats why hybrids normally have petrol, current diesels tend to have turbos instead on small engines.
There are a few diesels, like the VW Polo Bluemotion that outperform the Prius on the highway, (3.4 vs 3.9) but even it's automatic engine stop system (at traffic lights, coasting etc) on the Polo can't touch the hybrids ability in urban traffic. Plus in Australia the Air-con will use a liter an hour by itself with a diesel engine not being able to shutdown at the lights. The Prius Air-con is a DC powered inverter type that can run independently of the drive train. It also turns off when accelerating.
On charging efficiency:
That depends on the type of batteries and the charger used. Typically don't expect much more than 80-90% energy recoverable from a charge/discharge. SLA will be worse.
If you want something efficient then have a look at one of these:
NUNA5 consumption:
2000 W @ 110 km/h Charge: 1800 W in full sunlight
1450 W @ 100 km/h LiPol specific capacity: 0.2 kWh/kg
900 W @ 90 km/h Efficiency solar cells: 35%
Thats a crazy 14Wh per Km!!
But it gets better: Human Powered!
About 4Wh/km!!
Why go electric when you can get fit whilst propelling yourself along at 132kmh!
And they wouldn't even be able to book you for speeding!!
Russell
How fast were you going when you got booked? And how did they book a un-motorised vehicle that requires no registration? I would like to see in which state this is a part of the traffic act. What state do you live in?
dbin
Thanks for the link. Haven't heard of that one before. Is going on the list.
But this one is probably more likely atm and will likely be more popular and cheaper in that size range:
Toyota/Scion IQ
Of course the usual candidates like the Nissan Leaf and plug in Prius are on the list. All supposedly coming to Australia next year.
I would love to see this version of the Carver come out:
On the highway, if operating at an efficiency of 35% and using 3.9L/100km of petrol that contains 9.7kWhr/Litre the energy that is used to move a Prius is
3.9 x 9.7 x 0.35 = 12.3kWhr/100km
Assuming an efficiency of 85% for the cycle of battery-charge-discharge, the electricity use would be 12.3/0.85 = 15.6kWhr/100km.
Q1. For the Prius, what is the efficiency between the shaft of the electric motor and the wheels ?
If electricity costs 20cent/kWhr the fuel cost for electricity used at 15.6kWhr/100km is $3.12/100km.
If petrol costs $1.40/Litre, the fuel cost of 3.9L/100km for petrol is $5.46/100km.
Depending on the annual km travelled (e.g 12,000km), the annual $ saving can be used to decide the $ investment that can be justified (e.g. for 10 years payback at 12,000km/yr x saving of (5.46 - 3.12)cent/km = $2,800) for converting a hybrid so that it can operate using all-electric mode.
Q2. What are the environmental costs and how "sustainable" is the mining of Lithium and its widespread use in batteries ?
TonyT said:
Would you prefer a bungee jump or a test drive with 007 in Carver's helicopter ?
lol Tony
It's actually a gyrocopter, and as such the main rotor is not driven at all, it is only pushed along by the rear propeller, which forward movement then rotates the main rotor producing lift. If the motor fails you simply autorotates back down to earth like an aeroplane gliding, but you can land on just 30-40m of runway/road or grass.
It's pretty safe for what it is. You could add an BRS aircraft parachute if you wanted. provided you jetison the main rotor blades!
Otherwise you could have one of these instead, but with the Trexa EV drivetrain:
Flying:
But on the prius PHEV conversion:
Your calculations assume the maximum of 35% efficiency all the time. Even though the Prius can regulate engine and electric motor control mostly independently, it will not achieve such a high efficiency all the time. If you drive a Prius you will notice that the road conditions constantly change, up/down slopes and wind effects you never saw before become visible if you follow what is being displayed on the vehicles system screen. And because of these fluctuations, the relatively "soft" vehicle control to ensure reliability over consumption, plus the insufficient battery size/type to completely regenerate or offer most peak power, the real driving is considerably less than just the efficiency calculation. I am not sure at what speed this 35% efficiency is achieved at, and it would vary according to engine load.
Typically most combustion engines run at maximum efficiency at relatively high revs, this however equates to much higher road speeds than can be driven here in AU. The Prius is speed limited to 170kmh and 188kmh for the gen3.
Your 3.9l usage is also lower than real (and still comfortable) driving. BTW that is the figure for a Gen3 Prius, but expect 4.4l for city and 4.6l for country. Add 0.4l for Gen2. Your calculation of 12.3kWh/100km equates to 123Wh per km. In reality this is nearly half of what it consumes. Typically it's about 215Wh km at 100kmh and about 50% of the energy consumed at that speed is just to overcome drag.
Here a picture of the electric drivetrain, this includes the electric "CVT" type gearbox btw, and does not require a clutch. The output from the front cog drives the diff.
If you revisit your calculations considering the factors above, I'd expect your calculations will be fairly close to mine. Let me know if they are not.
In the meantime I'll be waiting for this one.
it only uses 1L/100km
JB. Thanks for another fantastic post and the very interesting links !
Can you provide a link with information about the second vehicle with its parachute ?
Is that vehicle "launched" by driving it over a cliff ?
The VW that delivers 1L/100km certainly sets a bench-mark !
I hope that someone will revive the Carver: pity it was so expensive. The auto-gyro version would be an even greater adrenaline rush.
My investigations so far indicate that a second-hand small car, converted to run on gas (? Getz, ? Yaris, ? Mazda 2, ? Polo), may be the vehicle for least-cost practical transport in 2011.
I had thought that a car that uses mains-electricity would be cheapest because it would avoid the taxes on petrol. However at 5L/100km the latest petrol and diesel engines look hard to beat.
Also, what are the environmental costs and how "sustainable" is the mining of Lithium and its widespread use in rechargeable batteries ?
TonyT
The paraglider car is http://www.parajetautomotive.com/
And no, you don't need to jump of a cliff with one of these! You only have to get it up to 70-80kmh and then it takes off from the ground like any other paraglider. (A bit like the Delorean in Back to the Future making the jump through time!)
The VW is called the XL1, they also had a L1 which was a tandem seater. They already have some versions of the Lupo and Polo in Europe that can achieve under 3l/100km, just with a turbo diesel with auto-stop for traffic lights etc. The XL1/L1 are hybrids though. I don't think it's possible or likely to get a petrol/deisel vehicle under 2l/100km without being a hybrid. It just wouldn't be drivable.
Add Honda Jazz to that list. My daughter has one and it performs flawlessly, good consumption around 5.6l/100km, but by far the best space arrangement and versatility for such a small, and well priced car. Quality is good too. That or if you have the money a new Polo, the TDI is pricey, but the TSI (petrol turbo) is a ripper as well.
Apparently the Honda Jazz Hybrid will be coming out this year or beginning of next in AUS. (They're already on sale in Japan). They are only a parallel hybrid though, ie electric assist, but are meant to produce less emissions than a Prius and use less fuel as well at around 3.3l/100km. In Japan they are only $2500 more than the standard model, so in Australia say 2x that...but still that will get you a 5 seater P-hybrid for around $23k. Not a bad buy if they can hit that price. Might be worth waiting for.
On emissions: The Prius does about 89g CO2/km. With coal fired electricity in EV only mode that would be about 200g CO2/km. With wind power about 7g CO2/km, with solar PV about 30gCO2/km, with Biogas (can also be done without batteries, similar to LPG conversion) minus -80gCO2/km. You'd drive around and reduce your carbon footprint by as much as a Prius produces in CO2!
I will have to look into lithium battery sustainability, I know we have an abundance of the material available: We only currently use 18000tons a year of it worldwide(don't forget it's super light), Of which 31% is for glass and ceramic production, and only 21% for batteries (and that with a billion mobiles etc already out there!). But the oceans alone have 280 billion tons of it floating around (which is harder to harvest atm), however the known easily harvestable ground based reserves are around 28 million tons, so about 1500 years worth of the stuff at current usage, if we don't recycle any.
The embodied energy of a Prius is about 30MWh all up, but that includes everything, of which the steel accounts for 44%, aluminium 13%, plastic 27% etc as well as the battery (%??), which is a Nicd btw. Which is the equivalent energy consumed by driving it 70,000km on unleaded petrol.
But another question for sustainable transport is what do we use instead of fossil derived bitumen and concrete for roads? The cars that drive on them are only part of the problem.
This one would beat them all if you added a little electric assist:
The Shweeb in NZ:
