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UC Davis Report Provides Overview of Goals and State of PHEV Batteries

Various PHEV targets and battery cell and pack potential mapped to a Ragone plot. Click to enlarge.

A report from the Institute of Transportation Studies at UC Davis provides an overview of the current state of several battery chemistries—including NiMH and Li-ion—and their abilities to meet the goals and subsequent requirements for plug-in hybrid electric vehicles (PHEVs).

The authors do not intend for the report to be a definitive analysis of the technologies, but a primer for battery non-experts, and as a way to inform electric-drive interest groups, “including researchers, policymakers, companies, advocates and critics” about fundamental battery issues “to facilitate more grounded debates about the present and future of electric-drive vehicles, including plug-in hybrid vehicles.

The report highlights four main conclusions.

  1. Battery goals or requirements for PHEVs are contingent on a number of assumptions, and differ greatly based on those assumptions.

    The “true” requirements of PHEV technology will depend on consumers’ driving and recharging behaviors as well as their valuation of different PHEV designs and capabilities. In turn, producer and consumer behavior alike can be shaped by government regulation, e.g., California’s ZEV mandate. Thus, while the USABC (and others) provides a useful benchmark for the future of PHEV battery technology, there may be a role for less ambitious PHEV designs, such as blended PHEV conversions, as well as Toyota’s demonstration of a PHEV Prius using NiMH.

  2. Battery development is constrained by inherent tradeoffs among the five main battery attributes: power, energy, longevity, safety and cost. No battery currently meets all of the USABC’s PHEV goals for these attributes. Attempts to simultaneously optimize power, energy, longevity, and safety will increase battery cost.

    Readers must be careful to understand the complex trade-offs among these attributes and among battery technologies. Certainly we must avoid assembling the best performances from different battery technologies on different drive cycles in different vehicles as an indication of the current state of battery technology.

  3. Li-Ion chemistries are better suited than NiMH to meet USABC’s PHEV battery design goals of high power and energy density.

    However, despite Li-Ion’s potential, the technology is not yet firmly established for automotive applications, and development must overcome issues of longevity and safety—and the resulting tradeoffs with performance—in order to achieve commercial success.

  4. Li-Ion technology is following multiple paths of development. An overview table in the report illustrates eight different directions, each using different electrode materials in efforts to optimize power, energy, safety, life, and cost performance.

    It is important, the authors note, not to generalize attributes about one battery—e.g, Toyota’s concerns about safety with its LCO battery—to all Li-Ion batteries.

    In addition, Table 5 also demonstrates the complexity and uncertainty of selecting a single technological “winner” among advanced automotive battery chemistries.

Click to enlarge.




Now why would they only list the life of the altair bat as good (15000 cycles)? ... is there a calendar life issue?




Is there a reason they did not list lithium sulfur batteries?


Interesting that they seem very high on the manganese titanium LiMnTi type formulas, but Panasonic which is making these for consumer electronics lists their cycle life at 500. Perhaps a Altair's nano-titanate chemistry would extend this out toward the 3000+ cycles needed for automotive apps.

Also the chart shows the battery type "MN" Manganese Titanium as having a graphite cathode. With no mention of the Ti element.


I found the actual report to be a bit pessimistic about the readiness of PHEV batteries which is understandable since it references Dr. Menahem Anderman, whom I would charitably describe as bearish on PHEVs. His recent PHEV market size projections are laughable low - "200 PHEV 40s (all electric) in 2012 rising to 1,000 in 2015."

I am surprised "that all of the USABC goals are set for the battery’s end of life. In other words, the power and energy goals described in the sections above must apply after 15 years of life regardless of use." (quote from the report) Wow. What manufacture states product "goals" for its end of life? Will similar goals exist for the rest of the vehicle after 15 years? This ridiculous approach to setting goals will ensure a ridiculously expensive product and a market flop. Maybe this explains Anderman's low projections


Lithium Phospate - Valence Batteries.
I would think should be listed as Saftey at "Excellent' that is why they are being used in school buses. And watch the safety video on thier website where they shoot the batteries with bullets and nothing happens. And thier third party safety report from Exponent rates it as extremely safe.

I would say it is out of the Pilot stage now and cost should be coming down rapidly as they ramp up production for their 70 million dollar order from Smith Electric Vehicles.


Good thing we didn't all have to use gas lanterns for the last 100 years until the new NiMH AA rechargeable were finally good enough for "electric" flashlights.

John Taylor

This is a hypothetical report on battery chemistry, not a real-world production report.

I would like to see a list of the top rechargeable battery production companies with their large scale battery productions *(car-capable) compared in price, chemistry, energy, and numbers manufactured.


The blended operation can significantly reduce the load on the battery. For example, if the trip computer knows the trip is 60 miles, there is no point to drain the battery in the first 10 miles.

After 10 years the car is going to be an old car. If the car is still drivable but with reduced mpg, then it's likely to be acceptable.



"What manufacture [sic] states product "goals" for its end of life?"

Well, automobile OEMs are very interested in part durability. It is not surprising that they are asking USABC to design to end-of-life specs. This way they can reasonably assure that the vehicle will perform as intended (advertised or expected) past the warranty period.

The US OEMs KNOW from their experiments (electric Ford Ranger, EV1, Dodge electric Caravan, etc ... yes, I just dated myself somewhat) that batteries are a durability weak link, so they have to overkill them ... and commoditize them.

@John Taylor

Battery market information is your to be had ... for a price ...

stas peterson

The problem with a rapidly changing field, is that by the time it is written, reviewed, edited, published, and distributed, teh Report is obsolete.

You can see by the discussions regarding some of the Li-Ion battery chemistries as 'Research' projects that research has gone pretty far, along the apth top commercialization.

Both the Chevy Volt batteries that are qualifying,would be considered Research chemistries in this paper.

From what I understand, both chemistries from the two suppliers hold the prospecxt of afery and potentially low cost. A123, Lithium Iron Phosphate, and LG Chem Lithium Polymer Spinnel, Battery packs, have passed early dynomometer testing and abuse testing, when packaged in a battery pack. Presumeably the weight and cubic capacity requirements are satisfactory, if not optimum, as well.


...and sodium batteries?

Henry Gibson

ZEBRA batteries have been in production for ten years and perform better or equally to the Lithium Ion batteries offered with the TH!NK, and give a 100 mile range..HG...


The report does not include the latest information since the latest information is being developed by the car companies and are currently confidential. Thus the report is necessarily outdated. A better indicator would be the proposed dates of production by the various manufacturers.

Ron Gremban, CalCars' Tech Lead

It seems, with certain lapses such as listing Altairnano batteries as having poor power capabilities (their specialty), this report does a good job of noting the state-of-the-art and tradeoffs involved. To its credit, the authors showed the EPRI PHEV-20 and PHEV-60 battery requirements and assumptions as well as the much more stringent ones of the USABC, and indicated that whether current batteries are up to PHEV commercialization or not depends upon as-yet-unknown actual customer requirements.

However, in their conclusions, they did not note that their own chart shows existing Varta NiMH batteries exceeding the EPRI PHEV-20 requirements and coming within a smidgen of meeting even the EPRI PHEV-60 ones (I have long insisted that existing NiMH batteries are quite sufficient for blended-mode PHEV-20s), or that early markets may well be amenable to higher battery costs and/or lower projected longevity, especially if government incentives are provided, ordinary fuel becomes scarce, and/or other industries contribute to battery ownership, leasing, warranty, and/or residual purchase. As with cell phones, plasma TVs, and other products, the first generation PHEVs need be neither perfect nor fully cost-effective; the purchases of early adopters will help fund and evolve their development and mass-production.


EPRIs PHEV-20 requirements may not be credible. The come out of the electric utility world and don't have expertise in transportation.

The United States Advanced Battery Consortium (USABC), an organization whose members are Chrysler LLC, Ford Motor Company and General Motors Corporation have skin in the game. I would pay attention to the USABC requirements. They understand drivers and their requirements.


As a boat captain, I've been shopping the new electric outboard and inboard motors; they effectively turn a boat into a "PHEV". The German company Torqeedo manufactures all of theirs with what they describe simply as a Lithium Manganese battery, and provide some stats and test results on their web-site. I have yet to see any negative reviews about that product, and marine products get a lot of scrutiny for safety and reliability. This product has been in production for at least two years. Doesn't look like any of the Manganese chemistries listed here are out of the pilot or development stage, nor do they match the efficiency claims made by Torqeedo. What's the deal?

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