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Toyota Marketing BS or Hybrid Limitation?

2415 Views 9 Replies 9 Participants Last post by  Wirecutter
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amchemist--Toyota is telling us that a reasonably large NiMH battery (they stated that they believe Li-ion technology is not yet mature) in their prototype plug-in Prius only gets them a short distance on electric power alone - I believe it was about 8 miles.OK, I could totally buy their statement, if it were not for one fact - the EV-1. The EV-1 was a BEV that could get around 120 miles on a single charge with NiMH batteries seven years ago. How can all this possibly add up? How can a 20-30 mile range be unreachable in a plug-in Prius with NiMH batteries, when a straight BEV greatly exceeded that range with NiMH batteries seven years ago?Can someone explain to me how all this adds up?Thanks
Either toyota is just saying this to discourage the notion of 100% electrics, or there is something about the hybrid drive train that creates a ton of resistance for the electric motor. Anyone know anything about this?
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It can't be a limitation if Hybrids Plus have already converted a standard Prius hybrid to a Plug-In hybrid and increased it's range from the standard 15 or so miles to 32 miles on one charge. Hybrids Plus used Lithium Ion in their PHEV conversion months ago.
If a private individual or company on a budget can do it well then Toyota can too.
Toyota is probably limiting the discharge of the batteries more than others might. Also, Toyota may be taking into account the cost of the batteries vs. how much people might be willing to pay for such a car.
Toyota even made the RAV4 with panasonic NiMH that goes over 100 mile on a charge and many are still in service in California at well over 100K miles on the same original batteries.

The key here is cost. The Prius 201v 6.8 ah NiMH pack cost about $5,000. The price started going down then with nickle prices jumping it went back up.

They can make a Prius that will go 50 miles ll electric but at what cost and weight ?

Lithium is lighter but also very costly. The Telsa 98K cost is about 50K for batteries to go 200 mile all electric at 2,000 lbs vehicle weight. The prius is 3200 lbs. Providing the range and cost that many could afford is the last hurdle. It will happen but takes a little time.

A123 is trargeting a prius pack for 60 miles at 100 mpg mass marketed in 2008 for about 12K with a 1 hour install. That maybe a 10 mile range all electric at 55 mph. They make make it happen first. will convert yours this year for $36K. I have to wait. You may be willing to pave the way for the rest of us at higher prices.
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My guess would be that they are so limited in range because they are trying to retain the cargo space of the Prius. It would be easy for them to get more range by putting a big battery in, but a lot of people aren't willing to compromise the cargo capacity of their cars.
If you take a look at the Prius battery vs the Rav4 EV battery, there is a massive difference. The Prius battery is a measly 6.5 Ah and the Rav4 EV has a 90 Ah battery. Both cars have a similar 288 Volt system.
Exactly as TheSGC said, it all comes down to battery capacity.

If the Prius has a battery pack of 288v and 6.8 Ah it only comes out to 1958.4 Watt-hours.

Where as the RAV4 has 288v at 90 Ah which comes out to a whopping 25,920 watt-hours, which is almost 26 Kilowatt hours!

If the RAV4 uses around 200 watt-hours per mile driven then it could have a 100 mile range.

If the Prius used the same 200 watt-hours per mile, it would have only around an 8 mile range.
The big NiMh batteries used in the EV1 and RAV4 EV are no longer available. Only batteries under 10 Ah are currently available. If you want to know why you'll have to ask Cobasys as they own the intellectual property for large format NiMh batteries.
I would respectfully have to argue here. Cobasys might have IP rioghts to the big suitcase battery packs they seel, but one can still do a NiMH battery without infringment.

These are just the large NiMH cells, and I could call them up and get 100Ah "off the shelf" (sort of).
I attended a meeting of the local EV club, where they were showing off a couple of "plug in hybrid" models of the Prius. One of the presenters was the manager of a large municpal motor pool which featured 50+ Prii (?? Priuses?) One had been converted to "plug in". What the "plug in" part is/was intended to do is increase the battery-only range of the Prius.

The consensus among those present was that the battery-only range of a standard Prius is in the neighborhood of 5-10 miles, provided:
1. You don't "lead foot" it.
2. You don't exceed 34 mph, at which point the IC engine automatically kicks in.
3. You don't use the heater, which gets its heat from the IC engine.

The "plug in" conversion consisted of a supplemental battery pack (20 motorcycle starting batteries, or some such) to help top off the existing Prius NiMH pack. The supplemental pack gets nothing from the regen braking or normal charging system of the NiMH pack - it's just used to boost the charge of the NiMH pack.

The conversion costs between $7K and $15K, and extends the "electric only" range to around 13 miles, more or less depending on conditions and driving habits. The reason the conversion is not more integrated into the drive system of the car is that nobody wants to void their warranty. If all it does is help the original NiMH battery, Toyota is apparently fine with it.

Another interesting thing is that, in the EPA mpg test cycle (or whatever it's called), the plug in version of the Prius has substantially higher emissions. In the normal Prius, during the EPA test cycle, the IC engine might cut in 30 or so times. With the plug-in conversion, the ICE comes on maybe 6 times. The ICE's duty cycle in the plug-in converted Prius makes it quite the polluter.

Why is this, you ask? Well, when the catalytic converter is cold, it doesn't work. It has to be (very) hot. So, when the ICE in the Prius comes on, they actually inject a bit of gasolene into the catalyst to get it hot. At that time, the exhaust is very dirty. Eventually, everything gets hot enough, the injected gas is completely burned, and the catalyst does its job. With the plug in conversion, the ICE doesn't run enough to get (and keep) the catalyst at the optimum temperature.

It's my humble opinion that the Prius is a typical compromise. Yes, it gets good fuel economy, but it's not a very good electric vehicle, and it's not a good ICE vehicle. Toyota made tradeoffs in order for the car to appeal to a wider audience. (I suppose they figured people weren't ready or able to plug their cars in whenever they parked.) Also, electric vehicles have a very hard time competing with ICE for the combination of range and performance. We're getting there, but we're not there yet. We are, however, far enough along that a lot of people could get around in EVs because they don't always need the range and speed of an ICE vehicle.

A Prius gets 50-60 mpg with the usual disclaimers. A Rabbit diesel could do this in 1980. I would submit that a Prius, given an appropriate diesel engine using current technology, would get better mileage than the hybrid.

I think the Prius' appeal is a combination of fuel economy and low emissions. The design was carefully thought out for this, and tampering with the original system brings things out of balance from the intended design. As EVs move into the forefront, hybrids will fade to the back. They probably won't go away, but they'll fade a bit.



...edited for spelling, 4Apr08
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