NateJG

...and if 1.9 kWh is the equivalent to just over 2.5 HP, it seems to explain why the ICE cycles on/off every dozen or so minutes while sitting stopped with just the radio and A/C running.

tus

1.9kWh is actually quite a bit of power. Even with the AC running, and using ~5000BTU as it's capacity, it should be able to get around an hour of use before draining the battery.

Besides the fact that the battery is never fully charged and discharged by the system to extend battery life, only using a part of the capacity, I suspect that the ICE fires up primarily to keep itself at operating temp, not charge the battery.

NateJG

The A/C load can reach as much as 3 kW*; and, as noted, the ICE doesn't run long enough to fully charge the battery - and the brain box doesn't let the battery discharge too low - which seems to coincide with my charge/discharge observations.


*ref: http://www.nrel.gov/docs/fy00osti/28960.pdf

vlad_a

And here comes the mandatory Toyota PSD read:
http://eahart.com/prius/psd/
The system is so simple and ingenious at the same time.

I would note that there was factor (for me) missing from the calculations, which is torque reduction or amplification based on gearing.
For example, MG1 (the very middle) is much smaller than MG2 (outer/wheels), yet MG1 has to provide torque in the opposite direction from ICE in order ICE power to be sent to the wheels/MG2.

NateJG

And while you're at it, see:


I contacted the author of Vlad's video to see if he was interested in doing a similar model of the RXh - but he wasn't.

Too bad. There are enough things different between the Prius and the current RXh (gear ratios and motor speeds) to be interesting.

it would also be interesting to model the two-speed GS-450h.

NateJG

Have you discovered the "Tech Stuph" that I've posted here?: https://www.clublexus.com/forums/hyb...ng-manual.html

I'd change the title for the thread, only I haven't figured out how. I post some of the more interesting tidbits that I've stumbled across - and wish that others might also post technical items of interest there.

salimshah

Due to traffic signal malfunction, I got stuck in a snail pace moving traffic. 450-H relied on fully charged battery [display near shows 100% for me, but it was showing all the way just short of the "+" tip. I did not time it, but I would estimate that it took 5-7min till it dropped to about 20% and the gas engine kicked in.

Conclusion .. there is not much juice in the battery.

Salim

MellonC00

Agreed. this happens all the time on the highway going back home........ shows how bad the Los Angeles traffic is. Thus the reason why my mpg sucks.....

-------------------

I found the answer as to why the size of the batteries are so huge on our cars, yet only contain 1.9Kwh of energy - this compared to Hyundai Sonata Hybrid (Non Plug-in Model) which as 1.6kwh battery in a tiny space. from EVWorld.com

"Lithium polymer vs nickel metal hydride

Compared with the nickel-metal hydride batteries in today's leading hybrid cars, lithium polymer batteries deliver the same power with 20-30% less weight, 40% less volume and 10% greater efficiency.

Lithium polymer batteries offer 1.7 times more energy density than nickel-metal hydride batteries, allowing Hyundai engineers to devote less space and weight to the battery pack. Lithium polymer batteries hold their charge 1.25 times longer. Lithium polymer batteries also are more resistant to changes in temperature, which improves cycle life. Additionally, lithium polymer's self-discharge rate is less than a third of a nickel-metal hydride battery and it is not dependent on the lanthanum supplies for nickel metal hydride batteries that are cornered by China."

BTW. I'm not referring to the plug-in cars. They have battery sizes that are triple that of the regular cars and I get that we'd have to give up the whole spare-tire space to get that kind of battery. But simply swapping out the NiHydride to Lipo battery would be nice for the next models......... Perhaps that can bump up our energy ratings to about 2.5 to 3 Kwh.....

Droid13

NiMH was state of the art in 1998, the safe and reliable choice. Problem is, it has proven so reliable Toyota found it too easy to stick with the status quo year after year after year as other battery tech finally got better on all check boxes. From reading a lot of Tesla battery studies, their cells seem to be standing up extremely well over the years, and that's with a lot deeper cycles than on our batts. The new cells coming out of the Gigafactory are supposedly even better. Of course, Toyota (as with any manufacturer except maybe Tesla to a degree) has no interest in providing an upgrade to existing cars in any shape or form that would threaten their trade in program.

vlad_a

When a Tesla does 200K+ miles on a battery pack without cell repairs, we'll talk then.
And how are them Nissan Leafs holding up? I hear their resale value plummets for some reason.

Toyota uses NiMh chemistry because it does not degrade over time. In fact, it has a very narrow charge/discharge operating range.
What we see as 0-100% is actually somewhere between 60 and 80% of the actual battery capacity. This provides the longest battery life.
Our traction battery serves as an energy buffer for the hybrid system, not a standalone power source. For that, it is actually perfect.
Of course, there is some influence from Panasonic being a large manufacturer of NiMh batteries.

vlad_a

That made my head spin, LOL. Lots of graphs to keep track off. Just proves how ingenious hybrid programming is.

F250

I cannot disagree with how "ingenious hybrid programming is", but "complexity" by itself is not the defining characteristic of "inventive" or "clever". Take the human brain as a perfect example... it is extremely complex, and yet so infrequently truly "clever" and "inventive".

Droid13

Electric cars are like TVs. So much improvement and so much more choice coming down the pipe. The original Leafs are like the first plasma HDTVs coming to market, cost a lot then and now can't give them away. The first gen Prius had an out of warranty battery replacement of 1%, the second gen was 0.003%, seems like small numbers, but that represents a 333% improvement in reliability. I think the electric car batteries are on the same track. My RX is like the 40 yr old freezer in my basement. Both are super reliable, work famously, but compared with today tech a massive energy hog, terribly inefficient for what it could do. How long will Toyota wait before letting go of their 40 year old freezers?

NateJG

I, for one, am happy that Toyota isn't using lithium polymer batteries - mainly because I don't want to be driving a potential bomb (note the recent cell phone fires, vaping device explosures, hoverboard explosions, etc use the lithium polymer* - LiPo - battery chemistry).

Their chemistry sustains fire - and is sensitive to overcharging, over-discharging, and extreme loads.

While it is great from a power density basis (my radio-control friends LOVE them) - I prefer the Lithium-Iron-Phosphate (LiFe) batteries** from a safety standpoint (they don't catch fire easily) - at this time - for my hobby needs.

I, too, wonder just how long to keep my RXh - just from a battery replacement standpoint -- and seeing that Lexus continues to use them suggests that they either a) made a wise choice, or b) simply want to delay admitting an "oops" -- either way, the cost of a replacement set is about what a replacement transmission costs -- and I seem to need one in any car that I keep for over 100K miles - so, I keep my fingers crossed.

Here is a nice link to a good explanation Lithium battery dos and don'ts: http://cobox-ebikes.com/296/basic-un...d-lifepo4.html

Tesla reportedly uses (or used) Panasonic 2170 Lithium Titanate Oxide (LTO) battery technology batteries. See: And
https://m.youtube.com/watch?v=mNk5l_3vGR8&feature=youtu.be

I'd love to hear anyone's data on whether or not driving technique (or the selection of Economy, Normal, or Sport use) has any significant effect upon battery life.

* https://www.thoughtco.com/why-lithiu...ch-fire-606814

** http://a123batteries.com/v/vspfiles/.../pdf/26650.pdf

NateJG

Agreed - but it's during those stop-and-go times that I get a kick out of watching my MPG go UP (with additional satisfaction in knowing that my engine compartment is getting Cooler)!