Lead-Acid Batteries Seek New Role in Hybrids, Plug-Ins
9/10/2012
Energy Power Systems (EPS) proposes replacement of a 16-kWh lithium-ion battery, like the one in the Chevy Volt, with a 9-kWh lithium pack and a high-power, 3.5-kWh lead-acid pack. (Source: EPS)
Hey Charles... i had thought about what Jerry is proposing... that lower output batteries might be the answer, I just didn't think that those would be that much cheaper per kwh...
Jerry...
As for cost we have been buying EV size lithium cells for $450/kwhr for a couple yrs retail so I don't expect it's costing GM even that. Add $100/kwhr for making it into a pack and BMS and you are at $550/kwhr.
But the claim here was reduction from $800/kwh so that's the starting point of the GM Volt's batteries right now.
Anyway, I can see where using a lead-acid battery to apply some punch at the starting block and then drawing slow and steady from the Li cells might be a good way to go.
oldtimer, the biggest problem is charging and balancing the cells thus the life of them. Most batteries don't die, they are murdered by over, undercharging or over discharging them. Sadly for the Bolder it wasn't very good at that.
You are right a big secret for not just lead batteries is low resistance interconnents and the paths to them from the active material. This cuts heat which causes most of lead batteries problems when not designed right/too cheap.
All lead batteries when fast charging, assuming good design, actually cool down until the 80%charge/gassing level. And don't slow down and even Bolders can explode. So while they like most lead batteries can charge as fast as they discharge, you have to be careful in the last 20%.
The Bolder or A123 are far superior to UC's in so many ways at a couple % of the UC's cost. Whenever I hear, read someone touting UC's I either see a con or gulible person as just not practical. Same about foolcells too.
Most of the weight in a Lead Acid battery is the in the lead grid that supports the active chemicals. Firefly Energy tried to solve the weight problem by replacing the lead grid with a support made from carbon foam. They didn't succeed. I'm not sure of the reason. It might have been technical or it may have been the money ran out before all the details were worked out. They were a technology spinoff from Caterpillar Corp. They started out in Illinois and got a fair amount of support from private and government funding but still went belly up. A company in India bought the technology and as far as I know is still working to develop it.
RalphyBoy, the answer to your question is below. The answer comes by e-mail from Subhash Dhar, CEO of Energy Power Systems. Note that Dhar cites the diminished need for thermal management. As we've reported many times, the National Academy of Engineering has estimated that about half the cost of today's lithium-ion battery packs lies in the packaging and thermal management system. Dhar is suggesting that some of that cost would be eliminated. See below.
Here is Dhar's response to your question:
"The Volt battery is designed for power and energy; it is assembled using three cells of 15 AH each in parallel to achieve 45 AH capacity; it also uses higher expensive conductive components to achieve power.
"In our hybrid battery the Li-Ion battery will not have parallel cells; these cells will be high energy cells without the need for higher power capability, which adds significant cost for thermal management.
"So the fewer number of higher capacity cells that do not have to deliver high power cost significantly less."
Gas / Lithium / Lead. I like it. It's a complicated problem we have, and I don't think there's a simple solution.
Charles, you could have titled your article "All that was old will be new again".
One poster said no one needs a car that goes 0-60 in 4 seconds and has a 300 mile range. I don't know who would give up a 300 mile range. If EVs / hybrids are going to be viable, they have to give us something close to what we have now.
I've been in discussions about a much larger battery pack than the Volt has, a unit for a trolly car, and thermal management did seem to be the name of the game in that instance.
I also worked on an upgrade to one of our lines that includes at the max end a 180Ah 200lb pack. The upgrade... heat management. So, point well taken.
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