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Firefly Energy Expands Into Truck Market With Group 31 Battery

Firefly Energy’s micro-cellular-based foam plates offer much greater surface area for optimizing the lead-acid chemistry than conventional lead plates. Click to enlarge.

Firefly Energy, the carbon-graphite foam lead-acid battery company (earlier post), is expanding into the trucking market with the commencement of a BCI Group 31 battery development program. Battery Council International (BCI) provides standardized definitions for the physical dimensions of a wide variety of batteries, and the Group 31 size battery is a broadly-deployed battery type in trucks.

The Firefly Group 31 battery will be available initially next summer with full production scheduled for the fourth quarter of 2008.

Firefly Energy’s development program comes several months before landmark trucking-related regulations take effect in the State of California. On 1 January 2008, diesel trucks operating in California face a five-minute idling limit. Traditional lead-acid batteries will be challenged by the severe strain of trying to support a trucker’s various “hotel loads” (air conditioning, TVs, etc.) which were previously powered by diesel engine idling. The result, says Firefly, will be premature battery failure since traditional lead acid batteries cannot easily withstand repeated deep discharging.

Truckers historically have bought batteries based on cold-cranking ratings and price. The game is now changing, and battery performance will become much more important in its contribution to trucker safety, comfort, and productivity. This calls for game-changing battery technology, which is why we are very excited to optimize our carbon-graphite foam lead acid battery technology for the needs of truckers.

—Ed Williams, Firefly Energy CEO

The as yet un-named battery will have a sealed valve-regulated design. The primary characteristic of the first Firefly Energy lead acid battery is the inclusion of a high surface area, non-corrodible and light weight carbon-graphite foam material. Firefly Energy’s 3D carbon-graphite foam delivers more of the high power potential of lead acid chemistry which was impossible to achieve in the past.

The technology not only reduces the lead content making the batteries smaller and lighter, but additionally enables faster, deeper and more reliable discharges and recharges. This significantly extends the battery’s life, makes it more environmentally friendly, and less expensive than lithium and nickel battery chemistries.

While conventional deep-cycle lead acid batteries used in truck starting show sizeable performance drop-off after some 200 deep discharge cycles, the Firefly Energy battery is capable of achieving more than triple the deep cycles while still maintaining more than 90% of its initial capacity.

The company’s 3D battery offers continuous power through the discharge process, a fast recharge to 100% capacity, excellent vibration resistance and greater cold-starting capabilities.

Typical battery life is extended since sulfation is reduced. When tested in cold weather extremes at -20°C, the batteries were capable of delivering above 65% of their rated “room temperature” capacity compared to 20% or less for standard Group 31 batteries. This can help minimize alternator damage incurred while attempting cold-weather engine starts when batteries are low.

The Group 31 battery is similar to a battery Firefly Energy is developing for the US Army to give combat vehicles enough on-board electrical storage to power equipment without significantly decreasing battery life.



Harvey D

Could these batteries be an interim solution to lower cost packs for first generation affordable PHEVs?


Sounds like it to me. It would at least be an improvement over the mini-BEV's the Chinese are making with AGM lead-acid batteries.


I think they have potential be more than an intermediate solution. Fireflys technology is suitable for exiting production lines. If energy/power density can be improved further it could provide a low cost solution compared to lithium ion chemistries. Another added benefit is that the components of the firefly batteries are easily obtained and there is already a recycling infrastructure in place for lead acid batteries.

Rafael Seidl

So far, the company isn't shipping any products yet. It already holds some patents related to negative electrodes based on carbon foam and has applied for more for positive electrodes.

The author of the technical backgrounder does a credible job of explaining why the high surface area afforded by the graphite foam matrix material permits designs that outperform the traditional plate concept in many important respects, including: capacity, charge/discharge power, operating temperature range, deep cycling longevity and prolonged disuse.

He's also careful to point our that graphite foam isn't a complete miracle: the resulting cells aren't quite as good as expensive NiMH or Li-ion chemistries. However, they are safer than conventional lead-acid designs and similarly cheap to produce. The new 3D2 concept, in which both electrodes feature graphite foam matrices, promises to be especially compact and lightweight.

In the automotive space, Firefly's 3D technology should be a good fit for micro- and mild hybrids, including peripheral-only PHEVs. Stop-start functionality plus hotel load at night could be feasible for HDVs, eliminating a lot of idling.

The 3D2 type looks very interesting for medium and full hybrids, especially light duty trucks. Application to full PHEV and BEV passenger cars might also be possible, provided EPA/CARB and customers all accept up front that the battery pack may need to be replaced well before the odometer reaches 150,000 miles. That would be an expensive repair job (cp. e.g. transmission rebuild) but acceptable if you know it's going to happen once in the lifetime of the vehicle. The spent batteries would be recycled.

There are many other markets that would benefit from high-performance lead-acid batteries: electric bicycles/trikes, buffer systems for power grids (esp. for light rail and building elevators), UPS systems for telephone exchanges and data centers, research submarines and, arctic climate monitoring stations, to name a few.


I want one of these for my Prius auxiliary battery !


One must be aware that if you install lead batteries inside a sedan, the batteries gases should be vented to the outside of the car. So be careful if you are looking to use these to convert an ICE sedan to BEV mode. It takes a tad more engineering to do it right. On a PU, throw away the gas tank and mount 'em below the bed, no venting problems. These batteries could be great for diy battery conversion projects. Find an old S-10 PU, gut it and go at it!


"The as yet un-named battery will have a sealed valve-regulated design."
There shouldn't be any venting problems.

Bill Young

I have been very intrigued by the Meyers NMG tricycle. Its cruising speed is fine but the range is a little short of my commuting needs. It is now equipped with sealed gel lead acid batteries. I figure if they would drop in Fireflies instead of their standard battery (as a direct 1:1 replacement), I could probably used a NMG as a daily commuter.


Does anyone know the latest progress with Firefly? I know that they have not shipped any batteries yet. They were partnering with 2 lead acid battery makers to produce the battery. It is said that they are to make batteries for a lawn mower maker and US Dept of Defense.

Until I see the batteries or read third party reviews of the battery, I remain a little skeptical.

Seeing is believing.


So, how many amp hours are we talking about here? Group 31 doesn't sound like anything I usually here talked about in traction packs or anything. Any chance we'll see more deep-cycle oriented products based on this soon?


I read on the EV word article Listed on the firefly website that the are targeting 250 - 300 dollars /kW with respect to 50$ for standard lead acid.

Does any know if theats the full 3D2 (close to NiMH in specific energy) or only the 3D (little better than current lead)?

isn't 300$/kw the hi volume Lithium target?




If I understand correctly, they do not claim significant improvements in energy density. They may be better than normal Pb-acid for hybrids, cold starting, deep cycling, etc.

BEV's, however, are primarily limited by energy density. It determines their range.


These batteries have a significantly better energy density in by weight over regular batteries (which is a killer for regular Pb-acid) and a cycle life over the 1K mark. At 5 times the cycle life of regular Pb-acid they are cost competitive at $250/kwh. And very competitive with the current Li bats at todays $1000/kwh. If they can get these to market in advance of $300 Li, then they have a chance to capture a significant portion of the market.

Rafael Seidl

@Shaun -

nominal volumetric capacity is a function of how much electrode material is actually involved in chemical reactions. More electrode surface area means more energy density per unit of cell volume.

The rest of the electrode is just there to provide mechanical support, electric conductivity and thermal conductivity. Carbon foam actually does a better job of this than lead.

Cyclic volumetric capacity depends on the cell design's susceptibility to various failure mechanisms, e.g. corrosion and sulfation. Here too, the Firefly technology should outperform traditional lead-acid concepts. That means you don't have to oversize the batteries by as much.

Gravimetric capacity also takes the density of the electrode material into account. The carbon foam matrix is much lighter than lead, though electrolyte and packaging also factor into overall weight.

So on both volumetric and gravimetric counts, in nominal and cyclic scenarios, specific capacity should improve significantly. It probably won't reach the lofty heights of Li-ion, but that has safety issues unless you resort to advanced nanoscale engineering. It's also a lot more expensive.


Hmmm.  At $300/kWh and 1500 cycles to 80% discharge (5 times the typical 300-cycle lifespan of conventional cells), battery aging would cost $375/1500 = $0.25/kWh.  Figure $0.10/kWh for off-peak charging plus battery losses, and the total cost of electricity from the batteries is 35¢/kWh.  A PHEV using 250 WH/mi would cost 8.75¢/mi; 200 WH/mi, 7¢/mi; 350 WH/mi, 12.2¢/mi.

Gasoline at $3.00/gallon costs as much as the 200 WH/mile PHEV at 43 MPG; 250 WH/mile, 34 MPG; 350 WH/mile, 24.5 MPG.  This looks extremely competitive.  As I said before, it only takes one workable technology to spell the end of the age of gasoline and bring about the final triumph of electricity.


E.P.: Does the firefly battery wear in a similar fashion as lithium? (shallow discharge causing less wear on the battery) Your calcs are encouraging when you consider that your numbers were even generous to the gas car. You're not always going to deep cycle your battery (longer life), even after 1500 cycles you still have a working (80%) battery and your calcs didn't factor in the higher maintenance costs of an ICE car (oil change etc..)


If this technology is so good why didn't the large battery manufacturing companies like Dephi, Exide and Johnson Controls develop it first?


Because serendipity led Caterpillar to it first (they spun off Firefly because it's not their core business).


Firefly did not develop this first - a company called Power Technology patented Reticulated Vitreous Carbon electrodes for PbA before Firefly. RVC has been around since the 60s - Phil Ross was using it for ZincAir batteries in the early 90s. As usual - the technology has been around for decades - the wonderful "free market" just ensures it never gets anywhere. We could have had these lightweight PbA batteries in the 70s or 80s. It isn't really rocket science to think of using a lighweight substrate to reduce weight and have a large surface area.

How about Carbon Aerogels? Then we could really get some massive Surface Area to Volume ratio.


Shaun, Rafael.
Energy in Wh of a lead-acid battery depends only on the amount of Pb and SO4H2 involved in the reaction. With this carbon matrix is possible to save in the weight of the grid used in conventional batteries (may be 25%,still heavy). However there would be great improvements in power density, deep of discharge and battery life.


"the wonderful "free market" just ensures it never gets anywhere."

Right, thats why it is breaking out in America today and not in Putin's neo KGB world.

So, you suggest we go the way of Russis, Cuba, Venezuela? I'm sure they're all finding fantastic new ways for battery, solar and EV transport?

The Free Market and Free Political system insures it gets out faster than any of the above.

Hindsight is easy, truth is ideas, technology improvements often languish in any environment. We can make improvements to our system. But, it is no accident this country has led the world for years in technology breakthrus and the following commercialization of technology.

And, we are teaching the world how to do it. China and Japan didn't spring into tech advancement because of Mao, Communism, or the Japanese Feudal system.

This is great news for advancement. Only a jaded person can possibly fault a "free market" system. Truth is the open market, investment features can rapidly change course better than any socialized managed system of bureaucratic mess around the world. And that is what is happening today.

Please, take a walk, or live in Belarus, Russia, Cuba, Venezuela for awhile. Where corrupt politicians own companies and prevent any true mechanism of oversight. Bribery, payoffs and look the other way is the name of the game.

Again, America is not perfect, but our system so far is far better than most. We can improve always.

Jim G.

"Where corrupt politicians own companies and prevent any true mechanism of oversight"

Communism stinks, no doubt about it, but it doesn't possess a monopoly on that! In some capitalist countries, it's only slightly different: the companies own the corrupt politicians who then prevent any true mechanism of oversight :-)

Having said that, I am an advocate of public subsidies for promising technologies if those policies will help, and if they can bring renewable energy forward where the market won't do so on its own. Your example of Japan is a good example of a fundamentally market economy which benefited from intelligent public intervention.


I expect the Firefly batteries to become much more affordable once production ramps up. No exotic materials are incorporated, only advanced manufacturing.
If these batteries become available soon, EVs will be cheaper than equivalent gassers in a few years. Then we can save money with EVs, eliminate petro-trash problems, be energy independent and cut US air pollution by 40 percent.

Ben Brown

Firefly is located not too far from where the fox valley electric auto association I belong to meets. Three years ago they said they really weren't sure there would be enough of a market for their battery in electric vehicles. Because of the stated interest in BEV's and PHEV's by multiple car companies things are looking more hopeful. Curious... how many major global sources are there for lithium and how many are there for lead? I really don't know... also how easy is it to recycle each SAFELY?

Ben Brown

Firefly is located not too far from where the fox valley electric auto association I belong to meets. Three years ago they said they really weren't sure there would be enough of a market for their battery in electric vehicles. Because of the stated interest in BEV's and PHEV's by multiple car companies things are looking more hopeful. Curious... how many major global sources are there for lithium and how many are there for lead? I really don't know... also how easy is it to recycle each SAFELY?

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