Nickel Metal Hydride Battery

CARB requires that the battery be warranted for 10years/150k miles to get the highest pollution rating and 8 years/100k miles otherwise. Toyota and others fear that Lithium will not last that long in hybrid use as the small hybrid battery (keeps cost down) will see many 40-50% cycles in that time as well as high peak currents (100 amps).

Good Lithium batteries are rated at several thousand short cycles and that may not be enough to go 100k miles in City or hilly terrain whereas at least the Panasonic NiMh batteries have proven that they can last in this use.

JeffD

 

Mass Production, Nimh version 4.0:
Prius c, V, III, ct200h, HiHy, RX450h.

Still having problems, Nimh V2.0
Honda

Automaker experiments, limited production, Lithium V1.0:
Nissan Leaf
Chevy Volt
Plug-in Prius
Prius V+
Hyundai Sonata Hybrid
Fisker Karma
Tesla Roadster

Except for Fisker and Telsa, the automakers can easily absorb a battery recall or class action lawsuit covering the entire fleet.

Right now, lithium chemistry is about where Nimh was in 2000. V0.x prototyping has been done, and a cautious rollout of V1.0 vehicles are being sold to customers. Automakers and battery suppliers need to see real world failure modes from their V1.0 cars to take the next step to V2.0. For example, I doubt that anyone at Toyota expected that the Plug-in Prius would be sold to people that NEVER plug it in -- the green HOV sticker jerks. At V2.0, automakers can hit the economy of scale that is possible when production goes up by an order of magnitude, bringing costs/kWh in line with Nimh. It will be a couple more years before we see that. For now, engineers and executives experience the sphincter pucker factor every time there is a negative story in the news about some battery problem.

On the Toyota side, I suspect the plan is that all non-PHEV hybrids have packs based on the new 5Ah lithium cell in the V+, probably by model year 2017.

I will go a step further and say that we won't see much if any Nimh after 2025, because lithium will be mainstream by then. The weight savings will be critical for automakers to meet new CAFE standards, as well as being critical for BEV range.

 

Yes, its more of an innovation stifling move. The prius got its current battery design in 2003, there were some minor problems with the original 1997 design. That means that we still don't have real world numbers for failures at CARBs 10 years. They can artificially age the batteries in the lab, but the best data takes the time. Honda software on their Nimh caused the batteries to age poorly, but this took years for them to figure out. How these batteries do will have a lot to do with how the cars are driven as well as software, heat, etc.

The original CARB rules were said to protect customers, but what they really look like was an attempt to punish hybrid cars like the Prius and insight in order to help what they preferred pure EV and Fuel Cell cars. Now that Nimh is proven, it is slowing adoption of Li and forcing car makers to add warranty cost to the price of a new car. Some car makers like hyundai would do this anyway, and are offering a lifetime warranty on their lithium polymer battery. But this probably has slowed toyota's adoption of lithium. It may have also helped prevent nissan and tesla from giving customers a range extending engine. The original tesla S concept was a phev not a pure bev.

The result of the carb rules are to slow adoption of hybrids and phevs. If your public charter is to reduce air pollution, this rule is an utter failure. The best way to make sure cars don't improve is to make those that use new technology more expensive.

 

101 is really low
the gen 2 is above that and also considered a clean car
for a way bigger car the + its not that bad
and even if its because the extra seats because yes thats the reason its still is Lithium instead of nihm.

 

It depends on the cycles. Li cells tend to have the same energy storage capacity no matter the cycle life, so if they can do N cycles to 80% dod then they'll also do 4N cycles to 20% dod.

NiMH cells otoh, while having less in the way of energy storage capacity at the extremes, have way more when exposed to shallow cycles.



A ~1kWh NiMH battery may only manage to store ~900kWh if it's discharged 90% routinely, but if it's discharged 60% routinely it can store ~6000kWh. That's a huge difference in useful energy storage versus dod, and it's why NiMH cells will probably be in hybrids for a long time (And also why taxis can rack up an obscene amount of miles on their packs).

Calendar life also complicates things, but generally speaking we'll probably see Li cells in applications where most of the capacity can be routinely used, and NiMH cells in applications where a fraction can be reasonably and consistently used.

 

For those that keep saying that a pure EV is harder on the battery than the hybrid, I'm not sure I can agree. While it is true that an EV must deliver more current to move the car since it is not just "assisting" a gas engine, it is also true that a true EV also has a much larger battery pack, so that work is spread out over more and larger cells. That is why I'm partially mystified at Toyota's 13-mile PiP. That battery has to work very hard to drive the car in EV mode and it will be completely cycled almost every time somebody drives the car. With my Leaf, I drive 10 or 15 miles per day, but that doesn't cycle the whole battery.

I am also very curious if any of the car makers have plans for large format NiMH batteries when the patents expire. I think it is a good technology and definitely has its uses.

 

Interesting thought, but not correct. Even with the much smaller battery packs, the batteries in hybrid vehicles like the Prius are cycled over a much smaller range than with full EVs. The usable charge in a Prius hybrid battery is only equivalent to a few tablespoons of gas - the battery is hardly used when compared to the much harder life of an EV battery.

Tom

 

So why did you buy one???
Oops, I missed your sarcasm too. Sorry!

 

Hehe I should be the national spokes men for the C I love it so much! Im even trying to figure out the way to legally marry the car here in California.

 

Don't just look compare at the cell level. If you look at the car, Sonata hybrid with Lithium HV battery weights more than the Camry hybrid with NiMH. We'll see how long Hyundai battery would last.

The weight difference between Prius Alpha 5 (NiMh) and 7 (Lithium) seaters is 10-20 kg depending on the trim.

 

Wouldn't that be moto-sodomy? A federal offense.

 

I am one of those people that never even considered a Prius until i found i could get all of the toys and gadgets found on other cars.. ie entune, bluetooth, heated seats, pushbutton start, etc....

aftermarket is great until that fancy aftermarket stereo shorts out part of the electrical system causing my aftermarket sunroof to stay open when im 1000 miles from home...

if the TOYOTA stereo shorts out the electrical system and causes my TOYOTA sunroof to stay open i drive to the nearest TOYOTA dealer for WARRANTY service.. alas well worth it for me to pay the extra $$ to get factory components installed at the factory..
-Christopher

 

In very bad city traffic, our new 'c' seems to spend the majority of it's miles in EV mode.


When going uphill, at 45 MPH in EV mode, I get the feeling this car is a wantabe EV..
(At least in heavy city traffic).
Being a noob, I have to ask.. Does the typical Prius 2011-2012 models use EV this much?

Thanks..

 

Priuses prior to the '11 model year don't have any sort of EV % display. I'm not sure about on the '12 (since the touchscreen LCD was added back as standard on that year).

 

I look forward to that day! For now, I'm considering a Prius c.

 

There are other factors in that though. When Tesla offered the Roadster, it was a tiny start up company and couldn't afford to offer mech of a warranty.
In addition, most all of the people buying Roadsters could care less about the warranty. They were early adopters that believed in EVs and were fortunate enough to have the ability to 'put their money where there mouth is'.

With the Model S, Tesla is providing a warranty up to unlimited miles for the 85kwh pack (8 years as I recall).

With proper battery management, I think Li batteries work much better for EVs than Ni.