Battery pack costs, cell costs

[hcsharp]

When we maintain batteries on NiCad's in aircraft we typically do not replace the entire battery unless there had been a thermal incident or other problem. What typically happens is that individual cells are replaced as they individually do no longer pass a capacity test. To me it would make the most sense to "maintain" these batteries in a similiar manner. With the ability of the car and diagnostic software to determine the cells no longer operating properly why not just replace those only. Plan on pulling the battery every 3 years or so, and replace those cells that are not performing. That way you have a more consistent maintenance cost, and not a large bill when the whole thing needs to be replaced, and a more consistent and stable battery.

Batteries work better when the cells are closely matched for both capacity and internal resistance. Replacing a few here and there might actually make it less consistent and less stable. The other problem, at least with the Roadster, is that it takes about 12 technician hrs of shop time to swap out the ESS. Not something I want to pay for every 3 yrs.

[dpeilow]

I think they have their hands full with the S right now and need to stay focused, not develop expensive mods for an old model. Not yet at least.

I disagree: The Roadster was originally built by a very small team and I see no reason why a seperate side business, almost like a skunk works, couldn't churn out upgrades without tripping up the S development.

For example, we know that the latest cells could give a near 400 mile range. I'm sure there are owners - possibly the same group as the early adopters - that would pay big money say they have that, providing a revenue stream for Tesla while keeping them way out ahead of the pack.

[vfx]

Many of us have had sheets replaced and the new batteries have to be balanced to match the others in the pack. Maybe it will be an all-or-nothing choice on going to a 400 mile pack.

Ignoring Roadster battery issues as they begin to "fail" would certainly make Tesla look bad and would certainly give EV haters a field day.

[JRP3]

I disagree: The Roadster was originally built by a very small team and I see no reason why a seperate side business, almost like a skunk works, couldn't churn out upgrades without tripping up the S development.

For example, we know that the latest cells could give a near 400 mile range. I'm sure there are owners - possibly the same group as the early adopters - that would pay big money say they have that, providing a revenue stream for Tesla while keeping them way out ahead of the pack.

I assume that everyone is currently working as hard as possible on the S roll out. Hiring and training an additional team to upgrade a handful of Roadster packs at this point in time might not be cost effective. It also might not be great press to hear that Roadster owners are replacing entire packs after only a few years. The conclusions drawn might be that the packs are failing quickly, or that purchasers were not satisfied with what they originally bought. I do see it happening at some point but I'd rather see it a year or more down the road.

[Iz]

When we maintain batteries on NiCad's in aircraft we typically do not replace the entire battery unless there had been a thermal incident or other problem. What typically happens is that individual cells are replaced as they individually do no longer pass a capacity test. To me it would make the most sense to "maintain" these batteries in a similiar manner. With the ability of the car and diagnostic software to determine the cells no longer operating properly why not just replace those only. Plan on pulling the battery every 3 years or so, and replace those cells that are not performing. That way you have a more consistent maintenance cost, and not a large bill when the whole thing needs to be replaced, and a more consistent and stable battery.

User maintained battery packs would be a great benefit to EV owners. The ability to replace cells or clusters of cells without having to replace the entire pack should be an objective. Of course replacing 8000 batteries cells is not an easy task. This is where larger cell formats may be advantageous. One would purchase the latest and greatest format cell and pop one or more into the pack. Yeah, it sounds far fetched but humans are close to discovering earth like worlds light years away.

[JRP3]

That's one benefit of building your own I can indeed pull out any single 100 amp hour cell and replace it fairly easily, one reason most of us DIY types don't use the higher density but more difficult to build with 18650 LiCo cells. However you wouldn't want to stick a single cell with different specs into the pack as it would make management difficult, though not impossible. Actually as long as it had the same voltage range and had larger capacity than the other cells it wouldn't matter too much. It would just have an easier life being shallow cycled compared to the others.

[dhrivnak]

The challenge with a Tesla Roadster battery is a DIY cannot fix or upgrade them unless one wants to spend a significant amount of money in a proper spot welder. Assuming you overcome the small issue of extracting the existing 1000lb battery from the underside of the Roadster. My understanding is there are two welds holding each battery so that is 13662 welds. That is well beyond my capability and I assume the majority of DIY. The larger format Prismatic cells are relatively easy to work with but matching the size and capacity of the Roadster capacity again will be impossible. But I would not think it would be difficult for Tesla to offer an upgraded pack as the newer higher capacity cells are the same voltage and size. So they should be able to easily swap them into the existing manufacturing process. Then I would think it would be an easy firmware update to reflect the larger capacity.

[Larry Chanin]

Battery Prices for Electric Vehicles Fall 14%, BNEF Says

The average price of lithium-ion battery packs for electric vehicles fell 14 percent in the past year as production capacity exceeded demand, Bloomberg New Energy Finance said.

Batteries cost $689 a kilowatt-hour in the first quarter of 2012, compared with $800 a year earlier, the London-based research company said today in a statement.

Prices for batteries have dropped 30 percent since 2009, making electric vehicles less expensive.

Larry

[richkae]

Battery Prices for Electric Vehicles Fall 14%, BNEF Says



Larry

You can buy 18650 cells at retail for $300 per kWhr. Wholesale prices for hundreds of thousands of cells at a time can surely beat that by a large margin.
Yes, yes, cells do not make a battery. But again with scale the rest of the battery electronics will be a lot less than $389 per kWhr - making a combined total a lot cheaper than their quoted $689 per kWhr.