NiMH vs Li-Ion battery - what's the deal?

I think Toyota chose both chemistry because of production capacity and maybe price.

We are hearing more and more about li-ion cells production capacity and how a serious EV maker will have to make serous factory for batteries. Now think about it, Toyota sells 1.4 million hybrids per year, each hybrid has 1.5 kWh battery (bigger average for Lexus batteries) That gives us 2.1 GWh of batteries per year. Now Nissan sells only 60,000 Leafs with 24 kWh battery that is only 1.4 GWh/year.

The point is it's not that easy to just switch to different type of battery when you have good cheap production capacity for NiMh packs. As the hybrid market is growing they just added new Li-ion battery in the production, but kept the old NiMh production capctiy. Now they are just mixing them into the market. For EU they probably opted for cheaper version because it could be that profit margin is lover in EU, because Prius is made in Japan and is taxed higher.

 

That analysis presumes that Li-ion and NiMH production are totally different streams. IOW, that a NiMH battery factory could not possibly switch to producing Li-ion, that a totally different factory (or supplier) would be required. For that matter, there are many different Li-ion chemistries: we don't know how easy it is to switch production between one Li-ion chemistry and another.

Another consideration is that Toyota's NiMH batteries have been redesigned for 2016 and (apparently) use a completely different architecture from the Gen 3 batteries. Can even they be produced by the same production lines as the previous design?

Tesla of course is building or has built a new battery factory (or more than one) but that may have to do with realizing economies of scale and gaining independence from third party suppliers.

IOW, it's not simple.

 

It's worth noting that the Gen 4 is nowhere near weight cutoffs, except for the Eco.

Test weight basis for cars is curb weight plus 300 pounds, and then this table is used to translate to test equivalent weight and inertia weight class.

The 3250 lb test equivalent weight class is for test weights from 3188 to 3312 lbs. Note that the Eco's curb weight is 3010 lbs, so it was manipulated to squeak into the 3250 lb class by only 2 pounds, which also gives it an inertia weight of 3000 lbs (the highest class that's allowed to be in the 3000 lb inertia weight).

All other trims (at 3050, 3075, and 3080 lbs curb weight) fit into the 3375 lb test equivalent weight class, and are pushed up into the 3500 lb inertia weight class. The Prius could literally have a curb weight of as high as 3512 lbs (and a resulting test weight basis of 3812 lbs, and a test equivalent weight of 3750 lbs), and it would still be in the 3500 lb inertia weight class.

For fuel efficiency marketing reasons, you want to be at the very top of your inertia weight class - see 3310 lbs on a 3000 lb dyno loading for the Eco. For "our real world numbers are better than EPA" reasons, you want to be at the very bottom of your inertia weight class - see 3350 lbs on a 3500 lb dyno loading for Three/Four. Toyota's playing both games.

I suspect that the real reason we don't see sunroofs available on the Tourings has less to do with weight (although it may affect the rolldown numbers if they have to have the equipment on the rolldown car) - Toyota could add as much as 57 pounds and stay in the same test equivalent weight class, and 432 pounds and stay in the same inertia weight class - and more to do with wanting to keep the share of Tourings under 33% of the Prius (not even Prius Eco, as I understand it) models in the ZVW51 test group. If you can get a sunroof on a Touring, many people would be more likely to buy a Touring, and then if it exceeded 33%, Toyota would have to report the Touring MPG separately from the non-Touring.

 

Thanks for this! Sounds exactly like what we expected: marketing. Which is fine, just nice to understand it.

 

I think you could buy the heaviest one in Japan, because they have the E-Four w/ NiMH option, go up to 1,460 kg in curb weight.
And according to their spec. table,
the sunroof / the 1500Watt DC-AC outlet / the Toyota Safety Sense P system each weights +10kg (v.s. base model)

 

When Gen3 came out I feel like we got a lot more open rationale from Toyota about why certain changes were made (lengthy YouTube technical video), cargo space and room vol, etc. Now I feel like we are little more guessing on design things which were probably requested by Toyota USA for the purpose of looking good in US market specs.

 

Keep in mind that Toyota's investment in NiMH goes farther upstream than battery factories. They went all the way up to nickel mines to lower cost ensure they had a supply to meet their demands.

 

In fact, with the 2014 Corolla, the Corolla and Avensis now share a wheelbase, in addition to already sharing a platform (although the Corolla's not quite as wide or long, and had a twist beam instead of the Avensis's multi-link rear suspension - but the Avensis is far, far closer in size to it than the Camry).

And note that the Prius is similarly sized to the Avensis, too...

 

Excuse me ... I'm relatively new to the Prius community, do you mean the Tech presentation by Chris Risdon to journalists at launch of 2010 Toyota Prius Hybrid in Orlando, FL. 03.27.09 ?
If true, is there any high quality version of it?

 

Yes I think that is the video...but seems like this version is not the original copy. Almost seems like the original was taken down (but I've viewed it recently for cargo space numbers) but the orig was not high definition either. I will try to see if my older links posted here link to a better version.

Try this link:

 

All I know is the Gen 4s, I have, get better MPG across the board over the Gen 3s. Also the Gen 4 in ECO has more power. My wife thinks the car is smaller on the inside but I don't. most likely more efficient use of space.

Great discussion with the jury still out. 8 years and we will have an answer.

 

Within a generation, selection of a mode (ECO, PWR, or Normal) has no effect on power.

Also, (I believe) that all reports have said that the power of the system is practically unchanged, although 0-30mph times were reduced in GEN IV, with the same 0-60mph times (relative to GEN III).

 

Tried power mode for the first time today briefly. Was nice. Felt good.

LG-H901 ?

 

Can only speak to personal driving experience of the same route. Mine has more available power in ECO going up the hill than the Gen 3. Same route for 14 years in hybrids and compared two 2016 Tourings to two Gen 3 solar in ECO mode only. Now I have not tried any of the other modes in the 2016.

Operational test for me and it passed.

 

some notes from the SAE 2016-01-1167 The New Generation Front Wheel Drive Hybrid System

 

I will be so glad when we can buy depressed robots.

 

Is the time scale really correct? Does the battery really "suffer" at 10-15kW for 15 s just to get rid of rubber band effect?

Why is there no less lag in acceleration [G] graph? Electric power should have quicker response than engine searching for right rpm.

 

I'm not seeing any actual lag in the acceleration graph, though - it's responding as quickly as the driver is applying the pedal, it's just using a lot more electric to keep ICE RPMs down, and therefore improve the driver experience for those who are used to the engine only rising some, not a lot, in RPMs, and then continually rising, rather than staying steady.

I'd guess that this helps efficiency, as well, because it means more of the acceleration event is done at lower RPM, and therefore a more optimal BSFC.

Of course, being able to do this sort of thing also likely explains the acceleration left on the table that bwilson4web found - you need to max out the engine RPM as well as the electric power to get maximum acceleration, and Toyota isn't doing this. Arguably, this would be an actual good use for "PWR" mode - actually increase the power. (It's worth noting that I'm of the opinion that PWR is pretty useless - if you're driving in a spirited manner such that you'd select PWR, you're probably getting deep into the throttle (let's face it, this is a low-powered car, and I just went straight for wide open throttle when I wanted hard acceleration, PWR does nothing over, what, 50%?), and therefore wouldn't notice much of what PWR does. If you're driving gently, PWR is just annoying IME.)