Comments on: EnerDel Gets GM Money to Develop Li-ion Batteries

By: Ports

Ports — Tue, 09 Oct 2007 14:44:41 +0000

The RackPack2 beats the EnerDel system on every front including price plus it has more features at a lower cost and the actual patents. They are at http://www.deviceconduit.com

By: Neil

Neil — Thu, 20 Sep 2007 16:34:15 +0000

Yes but: re Altair use in HEVs. Fast charge allows for better regen brake energy capture and the full DOD capacity makes up for lack of energy density (you don’t need to make the battery bigger than necessary and then avoid using the last 30% to save the battery)

By: Yes but

Yes but — Thu, 20 Sep 2007 11:47:57 +0000

Granted, I think Altair is more of a full BEV tech (where fast charge is a huge plus) and may not be leveraged for hybrids as well since that is not required.

By: Yes but

Yes but — Thu, 20 Sep 2007 11:40:34 +0000

But the key is to have all of the performance characteristics simultaneously in large format vehicle pack form and verified. I agree that the A123 cells are probably coddled more than necessary in the Volt design, but I don’t see any claims that they can be full DOD cycled like Altair’s and still provide the life and safety claims. You have to ask, are the power or life stats of the cells mutually exclusive? On most batteries there is a strong tradeoff and many battery companies site their best stats in each category from testing of different cells.

The first battery tech I know of that is being 3rd party verified to do it all at once in large format vehicle pack form is Altair through AeroVironment (who by the way GM worked with on the EV1). We’re not just talking about theoretical numbers or individual cell numbers, they are putting an actual battery pack through the paces, at rapid recharge.

Here’s an interview to listen to:

http://www.podtech.net/home/3227/aerovironment-charging-ahead

By: AES

AES — Wed, 19 Sep 2007 23:55:59 +0000

Altair’s specific energy (aka energy density) is somewhere around 85Wh/kg, possibly slightly more discounting the weight of the packaging material.

With regards to Enerdel and specific energy, their site has a figure showing the relative mass and volume of a conventional NiMH pack for HEVs compared with that of a hypothetical pack built using Enerdel cells. If you assume that this is a pack from something like a Prius, the NiMH cells can hold ~45Wh/kg. So this 36kg NiMH pack must hold 1.62 Wh. If the Enerdel pack holds the same amount of energy using only 23kg, (1620Wh)/(23kg)= ~70Wh/kg.

Compare that to power-optimized LiFePO4 at 108Wh/kg, and the prospect of something between that and 140Wh/kg with the 32 series cells. There is the “coddling” issue as you mention, but LiFePO4 really doesn’t *need* that much coddling to begin with.

My honest feeling is that lithium titanate is a great technology that should be actively explored in the years to come, but for now it doesn’t fit the bill for what’s needed.