2nd Battery for better milage ?

Lithium vs NiMH

Instead of having the NiMH Auxiliary Battery, they shall do research and replace the stock Toyota battery, with an lithium polymer battery that has can save more energy quicker and longer.

Honda has done research on lithium batteries.

 

so has toyota, their conclusion was that it isn't yet cost effective

 

definitely much more money, its too bad that it wasnt listed as a 3rd party option... some people will buy it just because its there no matter what the cost.

 

I suspect that at present-day prices, lithium batteries would add, not a few thousands, but a few tens of thousands to the price.

How many people would pay $60,000 for a Prius just to add 10 mpg to their present 45 to 60 mpg?

The cost of lithium batteries will come down. But they're not ready for the Prius yet. Look at the LiIon tZero: $220,000. It will appeal to the Ferrari crowd. Who's a $60,000 Prius going to appeal to?

(I've pulled all the above numbers --except the prict of the tZero-- out of my hat. But I think my point is valid: Lithium is still too expensive.)

 

well, i guess having the LiIon batteries as an option was basically the lack of thinking off the top of my head.

i was talking to a friend who works in mat.sci dept. at intel and he says that the entire charging and monitoring system would have to be different as the properties bet the two types of batteries are simply too different.

iow, the two types of batteries are not interchangeable on that large a scale. also, the LiIon batteries would be about 200-300% more expensive.

 

At the street fair here in Fargo there was a solar race car on display. I forget whether they used NiMH or Pb batteries, but I asked, Why not lithium? Answer: too frigging expensive. There's a separate catgegory for teams with deep pockets. But they have to be very deep to afford lithium. Also, the electronic charging/discharging circuitry is a lot more complicated because lithium batteries can explode if they overheat.

Lithium is coming, if they don't invent something better first. It's just not ready yet.

 

This is a fascinating topic.
I would like to see a Prius-like vehicle with a removable battery pack -- something the owner returns to the maker every year or two.
I would also like to see the vehicle capable of gathering every scrap of data related to energy efficiency and then invite the driver to conform to various objectives ("best energy saving," "best acceleration,") and then have the system seamlessly adapt and responsd to driver input (obviously turning off energy efficiency algorithms when the driver floors the throttle to avoid a collision or whatever) and I would like to see a variable displacement and variable forced-induction engine mated with a series (perhaps three or four) electric motors and a variable array of batteries (perhaps one or two 'stacks' for around town, perhaps two or three or four for short weekend trips and perhaps as much as ten stacks for long holiday driving on flat terrain or as few as one or two stacks as needed for various circumstances.)
I'd also like to see the Prius as an emergency home generator or as a home grid generator (when grid fossil electricity turns out to be more expensive than vehicle fossil energy etc.)
I'd really enjoy visting a holiday desitination, checking into my hotel and then receiving a pro-rata discount because my Prius delivered energy to the hotel at a rate cheaper than my cost, resulting in a "win" for the energy conscious consumer in an energy commodity society.
I'd love to have my Prius sitting in the driveway, feeding an inductive circuit. And my wife's Prius feeding a loop at her office or outside our daughter's school. Every month we'd receive a payment for energy our Prius' fed back into the energy matrix.
I live at 2000 ft and work at 100ft above sea level. I'd happily sell all that potential energy every day. I can envisage driving along a major freeway or aterial road and seeing the energy consumption display report cash inflow from energy sales.
The imagination runs riot with potential for energy sharing.
I'm preaching to the choir, but my primary concern in driving a Prius is to preserve this fragile planet for my children. Let's all try to leave it here for the next generation.

Cheers,

 

More battery capacity would indeed allow you to get more benefit out of a commute that went from a high elevation to a low one and back.

But a car that burns fossil fuel is never going to produce electricity cheaper than the grid for the simple reason that the grid can use power plants that are millions of times larger, and therefore much more efficient, and can burn cheaper fuels than required by an ICE.

However there is a group advocating the use of electric cars for distributed storage of electricity. The idea being to charge the cars' batteries at off-peak rates, and then sell some of that electricity back to the grid at peak times. This does not produce any energy (it loses some) but it implements "peak shaving" which reduces the need for peak generating capacity: we could get by with fewer power plants. Personally, I think it is rather far-fetched.

 

Far-fetched is the right description for most of these ideas. Still, I could see myself arriving at work and selling my overnight power at a market profit. Just as a solar house plan works already. I really like the idea of a "configurable" vehicle where I carry only the battery burden useful for my needs day to day -- the car could tell me "hey, you're driving to LA according to the trip plan in the nav system ... if possible, please load two more battery sleds." or "please remove all auxillary batteries for city driving" etc.

Anyhoot, it's just examples of the enormous potential (pun) in hybrids ... and I'll add that I think going from fossil to hydrogen is a distraction ... .better to refine (pun) hybrids and find a real solution while we buy time with high efficiency vehicles.

Cheers,

 

unless the power is generated by wind, solar or gravity, it would not be worth while. even high efficiency chargers are lucky to hit 60-70% efficiency...

when you see a charger next time.. touch it... every degree of heat is energy wasted.

unless superconductors become widespread, storing electricity by battery will always be a last ditch resort.

 

You can expect two things from adding a second (plugged in for grid recharging) battery to the Prius.

The first is a greater range in EV mode. The folk at PriusPlus are aiming for about 30 miles from their adapted Prii. However, you'd still be limited to the main battery's output of about 28hp, which means slow acceleration and low EV mode top speed so that can't be considered the main appeal of this conversion.

The second happy consequence, however, is often overlooked. By fooling the ECU into thinking the main hybrid battery is always at full charge (as a result of the large amount of charge topping it up from the second battery), the car runs in "assist" mode an awful lot more than normal, so the engine is barely working at all. This has led (in the prototype Prius+ at least) to highway mileages of up to 83mpg! With some tweaking, I expect such an approach could double the current mileage (and hence range per tank) of existing Prii.

I keep hearing - "Lithium is more expesive than NiMH!" repeated as a kind of mantra these days! It's just not true. OK it was back in the mid-nineties when Toyota and Honda were designing their hybrids but it's not anymore. To be fair though, if you called up Saft or someone similar and asked for EV sized LiIon packs, you'd be quoted a ridiculously high price (as the folks at AC propulsion discovered). This is because they'd have to make them from scratch, and you'd be paying a huge premium to develop essentially a new product.

BUT if you use a mature LiIon product, one that's been mass produced for years, has demonstrated reliability and safety in countless applications and that has had it's price eroded by a decade of price-wars between competing manufacturers, then the price is LOWER than NiMH. I'm talking of course about 18650s, the small Lithium batteries used to make up laptop and camcorder packs. For example, LG-Chem LiPoly cells weigh about 44g and are 180Wh/kg, so each cell can hold about 7.9 Wh of energy. In bulk, you can buy these for about $2.50 each. Thus, to achieve the ~1300Wh of the '04 Prius pack, you're looking at wiring up a pack made up of 164 individual 18650s, for a total cost of about $410. Compare this with the ~$1,000 you can expect for just the NiMH cells in the Prius battery.

Now assuming you want to add a 20 mile plug-in range to your Prius, you'd need about 4 kilowatt-hours of battery storage. Aim for 5 kWh though, to allow for only 80% discharging, which is good for longevity. In 18650 form, this would cost you ~$1,600 in cells alone and could potentially cut your (gas) fuel bills in half. Once people like those at Priusplus have succeeded in "hacking" into the complex HSD software, this conversion will become relatively trivial, but for now, until that's been achieved and the bugs have been ironed out, it's not for the faint-hearted! 8)

 

Thank you, Clett. That's encouraging. But I have a few comments:

1. To be fair, that 83 mpg figure accounts only for the gasoline, not the cost of current from the grid used to charge the secondary battery. Once we're using two separate energy sources we need to quit talking about mpg and start talking about cents per mile. Do you have such figures?

2. If they are "tricking" the ECU into running at a higher level of assist by making it think the HV battery is always full, then won't it quit using regenerative braking? It will think there's no room for the charge, and will use the friction brakes instead. You'd lose the regen, and wear out the brakes faster.

3. (And this is my real concern about the Priusplus project By the time the Priusplus folks figure out how to hack the ECU, Toyota will have accomplished all this and more in the next generation Prius. I'm dreaming of lithium batteries for greatly increased capacity, plus capacitors to improve the short-term current capability both in and out, and to improve current flow in cold weather when the battery's current flow is so greatly reduced.

 

Assuming $2 per gallon, in 45mpg gas-only driving you're looking at 4.5 cents per mile in gas costs. If it were a pure EV, assuming electricity to cost 7 cents per kWh, you're looking at 1.4 cents per mile, so running electric is about a third to a quarter the cost of running on gas. However, when mixing the two sources (as would be the case in a Priusplus) the true per mile figure will be somewhere in between. Obviously, the more electricity used, the closer it will be to 1.4 cents per mile, the more gas used, the closer to 4.5 cents per mile. Depends how much of each power source is used.

As I understand it they are also trying to hack it so that it does allow full regen. Haven't read their list for a while now, but last I recall was that they'd found a sweetspot (68% SOC?? something like that?) where they could get both full regen and full assist at all times, but don't quote me on that one - I'll have to check!

Prius Mk1 was '97 to '04, so maybe 2010, 2011 by the time Toyota come up with the next generation Prius? I agree, almost certain to be a plug-in hybrid as by then the plummeting cost of LiIon will have made it pretty much a no-brainer.

 

I thought the Mk1 Prius was the 1998 model year. But maybe it was 1997. I don't know. The Classic, a different model, was the 2001 model year. The 2004 model year is the present model, radically different from the 2001. That's 3 to 4 years between significant model revisions. I have read that 5 to 6 years is typical for Toyota. But since Prius is their flagship for new technology, 5 to 6 years may be long. I'd say 2009 at the very latest, but possibly as early as 2007 or 2008.

Plug-in will certainly make sense once the storage is available, but there are marketing considerations as well: Right now Toyota wants to avoid the perception of plug-in cars as a nuisance. But the greater the spread between gas prices and electricity prices, the less consumers will object to plugging it in, especially once they understand that with a hybrid, plugging it in is optional.

Overall, I'd be much more comfortable with technology that comes from Toyota itself than with a major aftermarket modification.

 

What we need are LiPoly (Lithium Polymer) batteries. I use them in my RC plane. They weigh HALF what a NiMh battery does and they have almost zero discharge while stored. They can discharge at very high rates.
They do need special charging circuitry or they will catch fire (probably why Toyota doesn't use them?).
They cost abot 20% more then NiMh in low volumes.