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I have no doubt that Toyota's under-seat hybrid battery has about the same capacity that its behind-the-seat battery did, i.e. Toyota has been able to shrink battery size down somewhat while retaining capacity but it is still not enough to give a reliable electric car the same range as an equal-size internal combustion-engined car.
Btw, is this battery you are referring to a lithium ion battery?
Does the new Prius actually have two battery packs?
A smaller pack sandwiched between the rear seat base and the fuel tank, plus a second and much bigger battery pack under the trunk??
What is the purpose of having two separate battery packs? Just more Amp-hour capacity?
That's why I'm wondering as we transition from ICE to EV, if we could swap the position of the fuel tank with the battery pack, such that the increasingly larger battery pack could be re-positioned wholey under the rear seat base, while the increasingly smaller than normal fuel tank could be placed under the trunk in the new Prius diagram below?
A small fuel tank under the trunk will take up much less space than the current under trunk battery pack below, and this may provide enough space for a space saving spare tire, as opposed to a spray can tire repair kit which is what overseas Lexus IS300h's presently use?
This "swapping" locations of the fuel tank with battery pack will give much lower center of gravity advantages, because the battery pack is much heavier than a fuel tank.
It also makes sense as we transition from ICE's to hybrids to PHEV's to EV's - we want fuel tanks to diminish in size, while battery packs increase in size.
The S Class Plug-In just uses a big battery pack under the trunk, however the new Prius' battery pack looks bigger, yet it has such limited range.
This Honda Fit EV has the battery wholey under the floor, however cabin space will be significantly diminished, and that's why the Tesla Model S sedan isn't as spacious inside as its exterior dimensions and wheelbase suggests.
The current Nissan Leaf is similar to the Honda Fit, but the Nissan Leaf compensates by making the Leaf a much taller & knobbier car in the first place.
^ They need to do what Tesla is doing, make the entire floor one big battery pack. The model S is a marvel of space efficiency and has a ton of room.
Regarding the forthocoming latest European fuel consumption and emission standards and the way it favors a comeback to hybrids, I was trying to think of a way they could modify the existing internal combustion engine ICE platform to fit the forthcoming bigger batteries below the rear seat of the hybrids for a lower center of gravity and a larger battery capacity for a longer EV range, without having to design an all new dedicated chassis like the Tesla Model S EV which can't accomodate an ICE for a hybrid.
The overseas Lexus IS300h 2.4L 4 cylinder hybrid has its fuel tank under the rear seats, yet the rear seat back rest can fold forwards as usual, while there is NO spare tire - this means the battery pack must be in the normal spare tire compartment, or close by???
However, I find that the IS300h has a diappointingly tiny battery pack, with an useless EV range, and on wide throttle openings, the electric motors are far too small and lethargic.
The overseas IS300h's need a much bigger battery pack, with much bigger and powerful electric motors, for both a longer range, and greater linear performance.
You have just proven just how primitive current battery technology is. The high-capacity, small-size, quick-charging battery is not (yet) available. This is why Toyota has stubbornly stayed away from building electric vehicles.
Because of the short range provided by current battery technology, many car makers offer plug-in hybrids. But that is a very fine balancing act, with many major compromises having to be made.
If you want any significant electric-only range, you need a HUGE, HEAVY and expensive battery, which takes up significant passenger space, like in the Chevy Volt. If you do not want to give up passenger space but are willing to give up some cargo space with a smaller battery -- like in the Prius Prime or the European luxury brands' plug-in hybrids -- you only have range of 30 to 40 km (20 to 25 miles). People may criticize a plug-in vehicle with only that limited EV range.
But even the smaller batteries of the shorter-range plug-in hybrids take hours to recharge from empty; you may as well leave it plugged in all night (or a significant portion of the day if you are lucky enough to be able to park at a charging station).
The current battery technology makes these batteries really only suitable for self-contained (never having to be plugged in) hybrid vehicles. But hybrid vehicles cannot provide much EV range. Even lithium-ion battery packs in hybrid vehicles will not give you significant EV range.
As I said above, adding battery capacity to a hybrid vehicle may, in fact, have a negative effect on fuel consumption.
And the electric drive motor power is also proportional to battery capacity and battery discharge rate. A high-power motor will drain the battery very quickly. A slow discharging battery will limit the power available.
Some more thoughts on EV batteries...
EV batteries are big, heavy things. There is no getting around that with the current battery technology.
If you want a long EV range, forget about the plug-in hybrid Chevy Volt; go and buy a true EV vehicle, like the Nissan Leaf. The gasoline engine just adds too much weight that takes away from EV range. If you want an EV, it is best to go with a car that was designed to be an EV (like the Leaf). Trying to fit an EV battery into the platform of a normal ICE vehicle involves too many compromises. Adding a battery to a normal car platform like the Camry, ES, IS, Chevy Volt, etc. means adding over the battery over the rear axle or under the rear seat (which limits space for the battery) or along the central tunnel (which limits passenger space).
Lithium-ion batteries are far from ideal for this purpose, which is why Toyota has stayed away from them (except for the old Prius Plug-in and new Prius Prime). These batteries are not as reliable as that old standby, the nickel-metal hydride battery (and we know that Toyota / Lexus is concerned about its reputation for reliability). There is a reason why airlines are very cautious about allowing lithium-ion battery-powered devices on board: they have a tendency to overheat, causing meltdowns or fires.
The Prius Prime, the MB S-Class Plug-in and Lexus IS 300h have only one battery. That small box under the rear seat (Prius Prime and MB) or in the spare tire well that you mistake for a battery contains the battery and charging controller electronics.
Very interesting Mr Sulu.
These big battery packs in these PHEVs are certainly compromising the trunk space, yet still don't have that much range - though better than an IS300h that I tested overseas recently, which probably couldn't even manage a mile on full EV mode.
Below is BMW 330e's big battery pack between the rear wheels, above the rear axle, but below the trunk.
Then Benz's C350e's trunk with the area between the rear wheels raised by the underlying big battery pack.
I still believe that if manufacturers swapped the position such that the battery pack sits under the rear seat bases, while the fuel tank sits under the trunk between the rear suspension towers, we would have a lower center of gravity, with a full size and full depth trunk.
The volume between the rear strut towers is very narrow yet long in the longitudinal dimension, while the volume beneath the rear seat base is wide, but shorter in the longitudinal dimension; in both positions, the depth should be similar.
As we transition from ICE to EV, we want the fuel tank to be progressively smaller, while the battery pack to be progressively larger, and this calls for an eventual swapping of positions/locations...
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In between the strut towers and beneath the trunk lining, is where previous generations of Priuses normally locate their big battery pack.
Meanwhile the old Prius's big fuel tank is positioned conventionally beneath the rear seats for an unecessary range of 800 miles!
The latest generation of Prius, Prius C, Yaris Hybrid, and the Corolla Hatch Hybrid, house both the new lithium ion battery pack and the fuel tank beneath the rear seat bases; both fuel tank and battery pack are encased in their own steel capsules.
Pic and sketch of the latest Prius, and photos of the Yaris & Prius C below.
The latest Prius Prime PHEV plug-in hybrid continues to house the huge battery pack behind the rear seats, between the strut towers, under the trunk lining, resulting in a trunk capacity that is much shallower and 7 cubic feet smaller than the standard new Prius Hybrid.
I wouldn't be surprised if this Prius Prime Plug-In has no spare wheel/tire under the trunk, and it only carried an aerosol tire repair spray can?
Presently, the standard Prius has a 4.4 kW-hr battery pack, while the Prius Prime has 8.8 kW-hr.
This Chevvy Bolt below has a 60 kW-hr battery pack; there are 5 stacks, so each stack is roughly 12 kW-hr.
Theoretically, two of these stacks could be used under the Prius Prime Plug-In's rear seats for 24 kW-hr; far better than the 8.8 kW-hr the Prius Prime PHEV is presently getting!
In future, it's just a theoretical possibility and theoretical move to have a bigger battery pack beneath the rear seats, while a smaller fuel tank is located in between the rear strut towers for a 400 mile range - which is enough; an 800 mile range like the current Prius is unecessary for most people.
The battery/fuel tank repositioning will help to lower the center of gravity, recover trunk space, and provide a bigger battery capacity for more power and range etc.
Once these issues are addressed, it is just a matter of addressing the additional weight, and most importantly addressing the additional cost issues, because many buyers are still reluctant to purchase hybrids, or even full blown electric vehicles, because the cost of ownership of a conventional gasoline powered ICE is still much cheaper than the ownership and running costs of a hybrid or full blown electric vehicle with the constant need to replace the battery pack roughly every eight years.
As hybrids improve in overall quality, sales will increase, and prices will fall...
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10-28-16, 12:10 AM
