AndyH said:
But might help enough if the cell is operated within bounds where it doesn't need much in the way of heat transfer, right?
Of course... but unless you have really expensive cells, that wouldn't be rapid charging.
KarenRei said:
I agree completely - so the real reason for auto manufacturers looking LiMn in general and at low-performance (2C) cells from Valence and others is pack price. Price is what pushes Ford Ranger EV and Chevy S10 owners toward HiPower and Thunder Sky rather than A123. But there are prices to pay either way. One can install NiMH to get the 100,000 mile pack life, but they pay for it in additional climate control complexity and lower efficiency. And they'll need larger cables on the level III chargers to feed the battery and climate control system.
Indeed. My point is that if you want an affordable pack *and* rapid charging, you need coolant.
I'm sure that if money was no object, you could make quite the rapid charge pack out of those new A123 cells with nothing more than a pack fan and some aluminum
KarenRei said:
Re, your sample Thundersky pack at 1.5C: that's a 40 minute charge. Hardly something that'll replace gasoline cars. Do you think the average American will wait 40 minutes for a recharge? 8 times faster, and you might have something.
Really? Don't tell me - I've been running a LiFePO4-powered motorcycle for the past year and I've not only moved 90% of my driving to the EV but at best have a 4-5 hour recharge from a 120V plug. I'm tickled to death that the leaf will triple my real-world range and will take less time to recharge.
Hey, I'm the same way. I have no problem spending more time charging than driving! But we need to accept that people like us are not the general public
KarenRei said:
And as for your "cools during charging" comment, you're still talking about lone cells.
Ok. I won't reference the DOE report that shows the early charge phase to be ENDOthermic, then. My mistake...[/quote]
Actually, I would be interested in seeing that, but I've never heard of a single cell that can rapid charge and end up cooler overall
KarenRei said:
I guess I can see this if one is totally fixated on the absolute fastest recharge.
Yep, that'd be me
My ultimate goal is for EVs not to be a novelty. I want them to do nothing less than take over every form of transportation on the planet -- no small order
And I have little confidence in human nature when it comes to willingly giving up a convenience, even if it gains you other conveniences, because the convenience you're familiar with is much more comforting than the one you're not. I mean, if human nature was like that, everyone who likes to read would own a Kindle by now.
In short, I strongly feel that with good hardware and software, EVs will fairly quickly accelerate through the single-digits share of global auto sales, but remain there or in the low double digits unless truly rapid charge (hundreds of kW) becomes a common option.
I would think it would be better to consider fast charging needs and management early on in the design cycle so that the product will fit the needs of the operator. I would expect a pack to look more like the Tesla if that were the case.
I don' expect the Leaf to rapid charge beyond 50kW -- at least not the early models. But I want the charging connector to be designed for that. Once a standard is in place and widely used, it's really hard to change. That doesn't meant that all connectors have to have coolant -- simply that the standard provide that they *can*, and that the data pins communicate capabilities appropriately. If they don't do it know, they're going to have to be retrofitting every charger later. Or worse, not retrofitting them, and making every vehicle have to haul around a sufficient cooling system.