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Firefly Energy Eyeing the Hybrid Market; Lead-Acid Foam Batteries for Mild-Hybrid Applications Heading to DOE for Testing and Validation

Firefly Energy’s 3D2 2V cell compared to conventional lead-acid 2V cell. Click to enlarge.

On Friday, Peoria, Illinois-based Firefly Energy presented US Senator Dick Durbin (D-IL) with a mock up of an HEV cell (based on its first-generation 3D technology) for a mild-hybrid application, similar to what the company will begin to ship to the Department of Energy (DOE) this quarter for validation and testing. Senator Durbin had earlier announced that $3.2 million in federal funds had been budgeted for Firefly, building on approximately $4 million in previous military funding. (Earlier post.)

Buoyed by that funding from the Department of Defense (DOD) '06, '07 and '08 budgets, Firefly Energy has been developing future generations of its carbon graphite foam lead-acid battery technology (earlier post) with an eye to eventually targeting the hybrid electric and plug-in hybrid electric markets.

The hybrid market is quite promising in the long term but currently fairly small and fragmented (as compared to existing lead-acid battery markets). Our strategy on this market has been to get the technology noticed and validated, keeping a small footprint of awareness in that market, until such time we’re financially and technologically capable of addressing it full force.

—Ed Williams, Firefly Energy CEO

The DOD funding is to support applications of several generations of Firefly technology to military battery requirements. Currently, that work includes both the first generation 3D technology and the second-generation 3D2 technology, according to Williams.

The 3D technology enables traditional lead-acid chemistry to function at levels closer to NiMH and Li-ion in terms of cycle and calendar life, including a weight/volume reduction of 20-40%—depending upon the application—compared to a traditional lead-acid battery. The 3D technology also eliminates the sulfation problem.

The 3D2 technology offers performance improvements over the original 3D, and will be the likely foundation for hybrid applications due to the performance and weight characteristics. While the 3D batteries still rely on a conventional positive plate, the 3D2 batteries use the porous foam material for both the negative and positive plates, replacing up to 70% of the lead utilized in traditional lead-acid batteries (or, another 30-40% weight reduction over the 3D batteries).

The 3D2 batteries deliver a jump in power, energy, and cycle life beyond the 3D product, and approximates the performance of lithium and nickel metal hydride batteries without the higher cost and/or potential safety issues.

The 3D batteries are easily delivering 38 Wh/kg, according to Williams, and the 3D2 cells deliver an even better gravimetric performance.

Foams used in the positive plate are affected to varying degrees when exposed to extreme overcharge conditions, according to Firefly. Electrochemical testing by Firefly has found that foams of certain graphite grades react differently in the upper potential ranges commonly experienced during recharge of the positive plate. Firefly says that it is actively refining and stabilizing foam chemistry as well as increasing the robustness of the foams used in positive plates through manipulation of both foam chemistry and processing, as well as methods of plate preparation.

In October 2007, Firefly Energy announced it was expanding into the trucking market with the commencement of a BCI Group 31 battery development program. (Earlier post.)




3D gain 20% * 2D3 gain 30% = gain 50% in weigth which bring it to 60Wh/Kg, good enough for an hybrid, definitely not good enough for a PHEV where you need at least 100Wh/hkg


I've been waiting for Firefly to come up on the radar screen again and now they have finally appeared. I would like to see them immediately produce their batteries for starter use in production automobiles, lawn tractors, etc; everywhere sulfation is a problem. With a lighter, higher energy density battery, the old Kragen specials are now obsolete. Their batteries might be just the ticket to launch common applications like an all-electric lawn tractor. Hurry and light up those fireflies! Corney! real Corney...I'm sorry!

Rafael Seidl

Start-stop and mild hybrid applications of this technology would be very welcome. These batteries should be a lot cheaper to produce than fancy NiMH or Li-ion units and, they should be able to support higher power levels at higher reliability than regular wet lead-acid designs.

Of course, these applications will only have a noticeable aggregate impact on energy security/global warming in very high unit volume. Firefly doesn't have the track record, funding or production capacity for that market yet.


IIRC, Firefly has been licensing their technology rather than going into volume production itself.  This is very prudent (no debt, can't go broke) and it also allows them to scale up very rapidly by licensing to a producer with deep pockets.

Harvey D


I agree with you. Firefly ESSUs will fly higher and faster if mass produced internationally at lower cost.

Potential worldwide markets exist in applications such as e-golf carts, e-lawn tractors, e-bikes, e-boats, lower cost city BEVs and as lighter more powerful regular 12 Volts and 42 Volts batteries for ICE vehicles. etc.

A low cost better lead battery will certainly have many applications for years to come.


Treehugger, 60 Wh/kg is a little disappointing in light of Firefly's prior statements. But 60 Wh/kg could work for a PHEV if the power density and cycle life at high DOD are there. $100/kWh buys forgiveness for a lot of sins.


I definitely think that Firefly is the way to go. If more and more cars are going to be hybrids in the world, the costs of Nimh & lithium will go up too as millions or cars are manufactured. The good thing about these batteries is that they used two cheap and abundant minerals, carbon and lead. And there is already an extensive lead acid battery recycling infrastructure in place.


Firefly-Energy has successfully blocked public usage of thier battery for another year again. Can someone put political pressure for an release date of yesterday! While the conservatives are in power, Oil is King.

Ron Gremban at CalCars

Firefly is being very smart by both licensing production to existing high volume PbA manufacturers and going after the quick markets for their existing 3D technology: truck starting, mild hybrids, and no doubt car starting once they can convince auto manufacturers of the economic advantages. However, I was also happy to hear about the challenges involved in getting the upcoming 3D2 technology going. At 60 wHr/kg or higher, $150/kWh or lower, long cycle- and calendar-life, production on existing battery assembly lines, known safety and charging control, it has the opportunity to dramatically reduce costs and speed up deployment of mass-produced PHEVs. 60 Whr/kg IS easily enough for practical PHEVs! A Prius PHEV with a 20 mile EV range would require a pack of only 183 lb, only 100 lb heavier than the existing Prius battery pack.

Ron Gremban at CalCars

I forgot to mention that at $150/kWh, the 5 kWh pack required for the aforementioned Prius PHEV would cost only $750, vs. today's cost of at least $500/kWh -- $2500 for NiMH or Li-ion cells only -- in automotive volumes.


So as sulfation is no longer an issue, maybe PSoC operation mode and matched BMS would make these cells last longer? I guess that the positive plate oxidation stress is the most significant contributor to the cell wear. Potentially a good solution prior to 3D2 introduction.


Maybe the ultra capacitor idea would help the lifespan of these batteries. Since their cost is lower, there might be enough money left to use those as well.

Henry Gibson

The nickel iron battery from Edison was to be the answer to the short lived and heavy lead-acid batteries in 1908. In 2008, long live FireFly batteries; they still use lead. Although a hundred year old working Edison battery is a distinct possibility. It is not even possible for the public to buy their simple positive grid technology. The problem with sulfating batteries seems to have been relieved with high frequency pulse technology. Grid corrosion and lighter weight seems to have been dealt with by EFFPOWER and Atraverda in similar but different ways including bipolar plates. As every college professor knows, if you are getting govenment contracts, you don't need to sell anything to have breakfast everyday. Venture funds are the same just ask Scuderi. Not even a small working prototype in ten years...HG...


Posted by: Word | Jan 14, 2008 7:07:38 AM
"Firefly-Energy has successfully blocked public usage of their battery for another year again. Can someone put political pressure for an release date of yesterday! While the conservatives are in power, Oil is King."

while i agree with word's point on firefly blocking consumers, i must say his point on conservatives in power is laughable. are you in a time warp? the liberals have been in power for more than a year, lol.
but, firefly, why are you holding out on us?
especially since you have received fed monies to make this battery happen. i want my tax dollars worth now, not in two to five years!

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